Though global temperatures are warming, winters in the Northern Hemisphere are still marked by cold snaps and extreme snowfall events — sometimes to an unprecedented extent, such as the 2021 deep freeze in Texas and Oklahoma that caused over $1 billion in damage.

Now, a new study suggests that these cold extremes are due to an increasingly common pattern in the polar vortex, the zone of low pressure that usually circulates over the Arctic. Disruptions to this vortex cause it to deform and stretch, spewing cold air into Canada and the U.S. These disruptions are becoming more common as the Arctic warms.

"Overwhelmingly, extreme cold and severe winter weather, heavy snowstorms and deep snow, are associated with these stretched events," study co-author Judah Cohen, the director of seasonal forecasting at Atmospheric and Environmental Research and a visiting scientist at MIT, told Live Science.

Cohen and his team looked at how these events evolve in the stratosphere, the middle layer of the atmosphere that starts about 12 miles (19 kilometers) up. Understanding how these patterns shift could help meteorologists make longer-range forecasts, said Andrea Lopez Lang, an atmospheric scientist at the University of Wisconsin—Madison who was not involved in the research.

"Knowing this information is useful for a lot of applications in energy [and] applications in insurance or reinsurance," Lang told Live Science. "How cold is it going to get? Are pipes going to burst? Are insurance claims going to spike this winter?"

Usually, the polar vortex circulates around the North Pole like a spinning top. Occasionally, it collapses dramatically, which usually leads to polar air rushing toward northern Europe and Asia. These collapses can sometimes cause cold snaps in North America — but not always.

"There's been this big question mark over what happens in North America," Lang said.

Related: US suffers record-breaking cold: What's going on with the polar vortex?

Cohen and his colleagues looked at stratosphere data from satellite observations between 1980 and 2021, as well as winter weather records from the same period. They found that, short of total collapse, the polar vortex often wobbles and stretches, like a figure skater flinging out an arm for balance in a tricky spin. There were five different common patterns in the stratosphere, the researchers reported in the journal Science Advances on July 11, and two in particular were linked to cold weather dipping into Canada and the U.S. during these stretch events.

Stretch events are increasing in general, Cohen said, but there has also been a shift in the type of stretches.

One of the stratospheric patterns tends to bring cold air toward the East Coast, while the other creates a chill in the Midwest and Plains region. Since 2015, the researchers found, the westerly pattern has been more common. It's not entirely clear why, but this shift seems to be associated with La Niña, a pattern of unusually cold temperatures to the equatorial Pacific Ocean. In the last couple of decades, there have been multiple multiyear La Niña events.

The researchers were able to detect some regularities in the way the polar vortex shifts between the five patterns, which might help improve forecasts over the two- to six-week period, Cohen said. "In that shorter range is the poorest accuracy," he said. "This paper can be helpful in that timeframe."

One big question is how these polar vortex trends might change over time as the globe warms, Lang said.

Cohen and his team have been looking at that question as well. The polar vortex is controlled by waves in the atmosphere, he said, and right now the most influential standing wave is over Eurasia, with a warm ridge to the west and a cooler trough to the east, which in turn is driven by patterns of warming in the Arctic.

Currently, melting sea ice is increasing the temperature differences between west and east, strengthening the wave that can disrupt the vortex, Cohen said. If the sea ice disappeared, the pattern might collapse and flip. Instead of surprisingly cold winter events despite overall global warming, winter might suddenly become much toastier.

"We could become more like the Southern Hemisphere where you rarely get a breakdown of the polar vortex," Cohen said, "and it would probably mean warmer midlatitudes and a colder Arctic."

Hurricane Beryl has become the earliest Category 5 storm on record, as unprecedentedly warm oceans cause powerful storms to form earlier in the year than ever before. 

The monster storm is currently sowing devastation across the Caribbean.

Despite appearing at the usually subdued beginning of the 2024 Atlantic hurricane season — a period running from June to November — the freak hurricane exploded from a tropical depression into a Category 5 storm between Friday (June 30) and Monday (July 1) as it traveled west. 

With winds topping out at 165 mph (265 km/h), Beryl has already caused widespread damage and killed several people across Carriacou (an island in Grenada), St. Vincent and the Grenadines. The storm, which has since slowed to a Category 4, is expected to next make landfall in Jamaica and then the Cayman Islands.

"In half an hour, Carriacou was flattened," Dickon Mitchell, the prime minister of Grenada, said at a news conference on Monday (July 1). "There is really nothing that could prepare you to see this level of destruction. It is almost Armageddon-like. Almost total damage or destruction of all buildings, whether they be public buildings, homes or private facilities. Complete devastation and destruction of agriculture, complete and total destruction of the natural environment. There is literally no vegetation left anywhere on the island of Carriacou."

Related: We may need a new 'Category 6' hurricane level for winds over 192 mph, study suggests

Scientists have been shocked at the storm's ferocity and how quickly it developed so early in the hurricane season. Brain McNoldy, an atmospheric scientist at the University of Miami, noted on June 30 that the previous record for a Category 4 hurricane in the same region as Beryl was set on Aug. 7, 1899, and the previous earliest date that a storm intensified at the same rate was on Sept. 1.

"It's hard to communicate how unbelievable this is," McNoldy wrote in a blog post. "With La Niña on the way and the ocean temperatures already looking like the second week of September, this is precisely the type of outlier event that people have been talking about for months heading into this season. When you have an unprecedented favorable environment, you're bound to see unprecedented tropical cyclone activity."

Hurricanes grow from a thin layer of ocean water that evaporates due to winds and rises to form storm clouds. The warmer the ocean is, the more energy the system gets, pushing the formation process into overdrive and enabling violent storms to rapidly take shape. This is why the most powerful storms in the Atlantic usually occur between August and September, when sea temperatures peak for the year.

Scientists previously discovered that climate change has made extremely active Atlantic hurricane seasons much more likely than they were in the 1980s. 

Since March 2023, average sea surface temperatures around the world have hit record-shattering highs — providing storms like Beryl with more energy in order to grow.

Another factor in the storm's record-breaking advance is the end of the El Niño weather pattern in April, according to the Australia’s Bureau of Meteorology. El Niño is a climate cycle where waters in the tropical eastern Pacific grow warmer than usual, affecting global weather patterns.

During El Niño, winds in the Atlantic are typically stronger and more stable than usual, limiting hurricane formation. But its end has removed the handbrake on Atlantic storm development.

Beryl could just be the start of a tumultuous hurricane season. As El Niño is set to be replaced by La Niña, it could make for an unusually stormy summer. That's because La Niña weakens trade winds and in turn lessens vertical wind shear, which is what breaks up incipient storms.

These factors led scientists at the National Oceanic and Atmospheric Administration (NOAA) to make their highest-ever May forecast for an Atlantic hurricane season, predicting 17 to 25 named storms. According to the forecast, 13 of these storms will be hurricanes, with winds of 74 mph (119 km/h) or higher; and four to seven will be major hurricanes, with winds of 111 mph (179 km/h) or higher.

Scientists are predicting a near-normal Atlantic hurricane season this year, with two to four major hurricanes reaching at least Category 3 status, with winds of 111 mph (178 km/h) or higher, the National Oceanic and Atmospheric Administration (NOAA) announced today (May 23).

But this "near-normal" description doesn't mean people in the U.S. Southeast and Eastern Seaboard can rest easy.

"That's a lot of activity," Gerry Bell, the lead hurricane season forecaster with NOAA's Climate Prediction Center, told reporters at a news conference today. "You need to start getting ready for the hurricane season now." [The 20 Costliest, Most Destructive Hurricanes to Hit the US]

The 2019 Atlantic hurricane season — which lasts from June 1 to Nov. 30 — is expected to have between nine and 15 named storms, which means they pack winds of 39 mph (62 kilometers/hour) or higher, NOAA reported. Of those, between four and eight could become hurricanes, meaning their winds reach speeds of 74 mph (119 km/h) or higher.

Although just four of these hurricanes may top Category 3 status, "it only takes one land-falling hurricane to cause great destruction to a community," Daniel Kaniewski, the acting deputy administrator at the Federal Emergency Management Agency (FEMA) told reporters.

During an average hurricane season, the Atlantic sees about 12 named storms, including six hurricanes and three major hurricanes. Last year's season was above average, with 15 named storms, including eight hurricanes, of which two were major — the destructive hurricanes Michael and Florence.

However, it's impossible to know whether any of the storms or hurricanes predicted for the 2019 season will make landfall, said Neil Jacobs, acting NOAA administrator.

The officials added that this year marks the first time NOAA's fleet of Earth-observing satellites, including three operational next-generation satellites, were used to gather data for the hurricane forecast models. This data also helped NOAA issue a storm prediction for the eastern and central Pacific basins. According to NOAA, the Pacific should expect an above-normal season with 15 to 22 named storms, of which eight to 13 are expected to become cyclones (the term given to "hurricanes" in these parts of the Pacific). Of these, between four and eight could be major cyclones, NOAA reported.

What forces are involved?

A near-normal Atlantic hurricane season may sound surprising, given that there is an ongoing El Niño this year — a climate phenomenon known for warming waters in the equatorial Pacific Ocean that can impact weather worldwide. El Niño also acts to increase wind shear in the Atlantic, which disrupts the flow of heat and moisture, ingredients needed for hurricanes to form.

In other words, El Niño often suppresses hurricane activity in the Atlantic, Bell said.

But this year's El Niño is weak, and it's competing with the other climate factors. These hurricane-favoring factors are warmer-than-average sea-surface temperatures in the tropical Atlantic Ocean and Caribbean Sea (a pattern seen since 1995) and a strong monsoon in West Africa, Bell said. "They favor more activity," Bell said.

What to do

People in hurricane-prone areas should make emergency plans now, Kaniewski said. This includes getting enough supplies — such as food, water and medicine — to last at least 72 hours, he said. In the event of a powerful storm or hurricane, people should also expect major communication networks to go down, so they should have a battery-powered radio to stay updated and have an emergency evacuation route in mind, he added.

Kaniewski also encouraged people to have cash on hand, in case the electricity goes out and ATMs and credit card swipe machines fail, as well as homeowners' and flood insurance. To learn more, download the free FEMA application, which provides a number of services, including weather alerts, lists of open shelters and advice on emergency preparedness.

• Hurricanes from Above: Images of Nature's Biggest Storms
• Photos: Hurricane Michael Toppled Over Trees and Uprooted 19th Century Artifacts
• Inside Irma's Eye: Hurricane Hunters Capture Jaw-Dropping Photos

Originally published on Live Science.

The largest child sacrifice on record took place after a torrential rainfall, when about 140 children and 200 young llamas likely had their hearts ripped out by the ancient Chimú culture in A.D. 1450, in what is now Peru.

The reason for the sacrifice, however, remains a mystery, according to a new study. Even so, the scientists of the study have several ideas.

For instance, heavy rainfall and flooding from that year's El Niño weather pattern may have prompted Chimú leaders to order the sacrifice, but without more evidence, we'll likely never know the real reason, said study co-researcher John Verano, a professor in the Department of Anthropology at Tulane University in New Orleans. [25 Cultures That Practiced Human Sacrifice]

Study lead researcher Gabriel Prieto, an assistant professor in archaeology at the National University of Trujillo, Peru, learned about the sacrificial site in 2011, after a father approached him while he was doing fieldwork on another project. The father described a nearby dune with bones poking out of it. The father said, "Look, my kids are bringing bones back every day, and I'm tired of it," said Verano, who later joined the project in 2014.

Once at the dune, Prieto immediately realized that the site had archaeological significance, and he and his colleagues have been working on it since, excavating and studying the human and llama (Lama glama) remains at the site, know as known as Huanchaquito-Las Llamas.

"It's the largest child sacrifice event in the archaeological record anywhere in the world," Verano said. "And it's the largest sacrifice with llamas in South America. There's nothing like this anywhere else."

Who were the victims?

The site holds the remains of at least 137 boys and girls and 200 llamas. Many of the children and the llamas had cut marks on their sterna, or breastbones, as well as displaced ribs, suggesting that their chests had been cut open, perhaps to extract the heart, the researchers wrote in the study.

The children ranged in age from 5 to 14 and were generally in good health, according to an analysis of their bones and teeth. These youngsters were wrapped in cotton shrouds and buried either on their backs with extended legs, on their backs with flexed legs or and resting on one side with flexed legs. Many were buried in groups of three and placed from youngest to oldest.

Some had red cinnabar paint (a natural form of mercury) on their faces, and others, especially the older children, wore cotton headdresses. The llamas were either laid next to or on top of the children's bodies. In many cases, llamas of different colors (brown and beige) were buried together, but facing different directions.

Also buried at the site, near the children's remains, were the bodies of two women and a man. These adults do not have cut marks on their sterna, suggesting their hearts weren’t removed. Rather, one woman likely died from a blow to the back of the head and another suffered from blunt force trauma to her face. The man had rib fractures, but it wasn't clear whether these injuries happened before or after death, possibly due to the weight of the rocks that were placed over his body, the researchers said. [Photos: Hundreds of Mummies Found in Peru]

The children weren't buried with any discernible offerings, but the researchers did find a pair of ceramic jars and wooden paddles on the edge of the site, next to a single llama.

What happened?

The Chimú culture dominated a large part of the Peruvian coast from the 11th to 15th century. It thrived, in part, because of its intensive agriculture; the Chimú watered their crops and livestock with a sophisticated web of hydraulic canals, the researchers wrote in the study.

This area is typically dry, drizzling only a few times a year. But it's possible an extreme El Niño event, when warm water evaporates from the southern Pacific and falls as torrential rain on Peru's coast, caused havoc in the society, not only flooding the Chimú's lands but also driving away or killing marine life off the coast, Verano said.

Evidence shows that when the children and llamas were sacrificed, the area was sodden with water, even capturing human and animal footprints in the muck that still exist today. It's unclear why this particular site, located almost 1,150 feet (350 meters) from the coast about 2 miles (3.2 kilometers) north of the city of Chan Chan, was chosen for the sacrifice, but researchers have some idea for why the children were chosen.

Children are often seen as innocent beings who aren't yet full members of society, and thus might be viewed as appropriate gifts or messengers to the gods, Verano said.

Moreover, these children were not all locals. Some of the children had experienced head shaping, and an analysis of carbon and nitrogen isotopes (an isotope is a variation of an element) in their remains showed that these kids came from different regions and ethnic groups within the Chimú state, the researchers found.

It's unclear why their hearts were removed, but "worldwide, everyone is aware that the heart is a very dynamic organ," Verano said. "You can feel and hear it beating. It's very vital. If you take the heart out, a lot of blood comes out and the person dies."

Today, some people in the Peruvian highlands and Bolivia still remove the hearts from sacrificed llamas, Verano noted. Sometimes the removed heart is burned and the animal’s blood gets splashed on places like mines, a measure thought to protect the workers within. However, it's unknown how the Chimú viewed and treated hearts in antiquity, Verano said. [Photos: Ancient Circular Geoglyphs Etched into the Sand in Peru]

The children's remains are now safely stored by Peru's Ministry of Culture, and the researchers have submitted permits so they can continue to study them, Verano said.

The discovery shows "the importance of preserving cultural patrimony and archaeological material," Verano said. "If we had had not dug this, it would probably be destroyed now by housing and urban expansion. So we've saved a little chapter of prehistory."

The study is "an incredible insight into the ritual and sacrificial practices of the Chimú kingdom," said Ryan Williams, a curator, professor and head of anthropology at The Field Museum in Chicago, who has worked as a South American archaeologist for more than 25 years.

He added that while human sacrifice is reviled in our modern society, "we have to remember that the Chimú had a very different world view than Westerners today. They also had very different concepts about death and the role each person plays in the cosmos," Williams, who was not involved with the study, told Live Science in an email.

Given that the sacrifice may have been in response to devastating floods, "perhaps the victims went willingly as messengers to their gods, or perhaps Chimú society believed this was the only way to save more people from destruction," Williams said.

The study was published online today (March 6) in the journal PLOS ONE.

• 7 Bizarre Ancient Cultures That History Forgot
• Photos: The Amazing Mummies of Peru and Egypt
• Photos: Mummy Hair Reveals Ancient Last Meals

Originally published on Live Science.

Evidence is mounting against the so-called climate change hiatus — a period lasting from 1998 to 2012 — when global temperatures allegedly stopped rising as sharply as they had before. This misconception can be explained, in part, by missing temperature data from the Arctic, a new study finds.

That seeming pause in rising global temperatures had been used as evidence by climate skeptics to suggest that the Earth wasn't really warming at an unnatural pace.

To get around the data gap, researchers from the University of Alaska Fairbanks (UAF) and China created the first global data set of surface temperatures. They filled in the missing puzzle piece with data taken from buoys drifting in the Arctic Ocean during the so-called global warming hiatus, the researchers said. [6 Unexpected Effects of Climate Change]

"We recalculated the average global temperatures from 1998 to 2012 and found that the rate of global warming had continued to rise at 0.112 degrees Celsius [0.2 degrees Fahrenheit] per decade, instead of slowing down to 0.05 degrees C [0.09 degrees F] per decade as previously thought," study co-researcher Xiangdong Zhang, an atmospheric scientist with UAF's International Arctic Research Center, said in a statement.

The new estimates reveal that the Arctic heated up rapidly during this period — more than six times the global average, said Zhang, who is also a professor with UAF's College of Natural Science and Mathematics.

Mind the gap

The reason for the data gap is simple: The remote Arctic doesn't have a robust network of instruments that collect air temperature data, the researchers said.

To fill in the gap, the team used temperature data collected from the University of Washington's International Arctic Buoy Programme, which allowed them to reconstruct Arctic surface air temperatures from 1900 to 2014, the researchers wrote in the study. The researchers also used newly corrected worldwide sea-surface temperature data from the National Oceanic and Atmospheric Administration. (Government temperature datasets are corrected, that is, vetted, before their official release, Live Science previously reported.)

The researchers incorporated the Arctic information with the global data. Then, they re-estimated average global temperatures from 1998 to 2012 with more accurate and representative data, Zhang said.

The hiatus

The hiatus is a controversial topic among climate scientists. At the time and following the hiatus, many researchers acknowledged that temperature data indicated that the Earth was still warming, but not as rapidly as it had prior to that 14-year stint. Climate change doubters seized on these findings, using the pause as evidence to show that man-made climate change wasn't real, Live Science previously reported.

Over the past century, Earth's average temperature has increased as human-made technologies emitted more greenhouse gases, such as carbon dioxide, that linger in the atmosphere and trap heat.

That's why the so-called global-warming hiatus confounded scientists. Some researchers suggested that the unusually warm 1997 to 1998 El Niño, and a long period afterward without an El Nino in the tropical Pacific Ocean might have diminished the rate of global warming.

However, the new findings show that this pause didn't happen after all, the researchers said. Moreover, the study shows that Arctic temperature data is key when calculating climate change. Until recently, many scientists didn't think that the Arctic was large enough to greatly influence average global temperatures, Zhang said.

"The Arctic is remote only in terms of physical distance," he said. "In terms of science, it's close to every one of us. It's a necessary part of the equation and the answer affects us all."

Another 2017 study, published in the journal Science Advances, also recently cast doubt on the so-called hiatus. That study showed that inconsistent water measurements helped lead to the hiatus misconception, Live Science reported.

The new study was published online Monday (Nov. 20) in the journal Nature Climate Change.

Original article on Live Science.

The hurricane season is likely to be extra active this year, thanks to a likely no-show from El Niño.

The National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center released an updated hurricane season outlook today (Aug. 9). The new prediction ups the odds for a blustery, extremely active hurricane season – and possibly even the most active since 2010.

"We're now entering the peak of the season, when the bulk of the storms usually form," Gerry Bell, the lead seasonal hurricane forecaster at NOAA's Climate Prediction Center, said in a statement. "The wind and air patterns in the area of the tropical Atlantic and Caribbean where many storms develop are very conducive to an above-normal season. This is, in part, because the chance of El Niño forming, which tends to prevent storms from strengthening, has dropped significantly from May." (El Niño is a climate phenomenon most distinguished by the shift of warm water from the western to the central and eastern tropical Pacific Ocean.) 

One other factor fueling a more active hurricane season: The waters off the tropical Atlantic Ocean are warmer than usual.

The new forecast puts the odds of an above-average season at 60 percent, up from the initial forecast of 45 percent in May. In addition, the forecast now predicts between 14 and 19 named storms, or those with sustained winds of 39 mph (62 km/h),  and between two and five major hurricanes with sustained windspeeds of at least 111 mph (178 km/h).

The NOAA center typically puts out an initial hurricane forecast in late May. This year, they initially predicted between 11 and 17 named storms and between two and four major hurricanes, and about even odds for an average and above-average season.

So far, the season has already had six named storms, double what's typically expected by this point. (The storms were Arlene, Bret, Cindy, Don, Emily, Franklin and Gert). Typically, it takes six months to rack up that many storms; an average season has 12 major storms, six of which become hurricanes and three of which are major hurricanes. Hurricane season typically lasts from June 1 to Nov. 30.

Originally published on Live Science.

The year 2016 was one for the record books, at least when it comes to the weather. Last year had the highest global temperature in modern history and extremely high levels of carbon dioxide and sea level rise, as well as exceptionally low levels of Arctic sea ice, according to the United Nation's World Meteorological Organization (WMO).

These alarming weather events and trends are continuing into 2017, the WMO said in a report released Tuesday (March 21).

The report — part of the WMO's annual State of the Global Climate — pulled data from multiple international datasets that are independently maintained. In addition, for the first time in its more than 20-year history of issuing these statements, the WMO partnered with other United Nations branches to include data on social and economic impacts of climate change. [The Year in Climate Change: 2016's Most Depressing Stories]

"This report confirms that the year 2016 was the warmest on record — a remarkable 1.1 degrees Celsius [1.98 degrees Fahrenheit] above the pre-industrial period, which is 0.06 C [0.1 F] above the previous record set in 2015," Petteri Taalas, the WMO secretary-general, said in a statement. "This increase in global temperature is consistent with other changes occurring in the climate system."

For instance, globally averaged sea-surface temperatures also experienced record-breaking highs, Taalas said.

"With levels of carbon dioxide in the atmosphere consistently breaking new records, the influence of human activities on the climate system has become more and more evident," Taalas said. Scientists are able to connect these high temperatures and some extreme weather events to man-made climate change by using long-term climate data and high-powered computing tools, he added.

Some of 2016's extreme weather events include severe droughts that caused food insecurity among millions of people in southern and eastern Africa and Central America; Hurricane Matthew, which carved a destructive trail through Haiti in October 2016 and was the first Category 4 storm to make landfall there since 1963; and heavy rains and floods in eastern and southern Asia, according to the WMO.

Mercury rising

Each of the 16 years since 2001 has been at least 0.72 F (0.4 C) warmer than the long-term average for the 1961-1990 base period, the WMO said. Every decade, temperatures have warmed 0.18 F to 0.36 F (0.1 to 0.2 C), the organization added.

The El Niño of 2015 and 2016 explains, in part, why 2016 was so hot. On top of warming long-term climate change temperatures, the weather is usually warmer during strong El Niño years, including 1973, 1983 and 1998 — years that had temperatures between 0.18 F and 0.36 F warmer than background levels.

During El Niño periods, warm water in the western tropical Pacific Ocean flows eastward toward South America, and heats surface waters off the coast of northwestern South America. These warm waters evaporate easily, and can fuel Pacific hurricanes and other unusual weather events. The temperatures of 2016 were consistent with this pattern, the WMO said.

Sea levels worldwide also rose so much during the recent El Niño event that early 2016 levels broke record highs. Meanwhile, global sea ice cover recededmore than 1.5 million square miles (4 million square kilometers) below average in November.

Higher ocean temperatures have contributed to coral bleaching and mortality, even in tropical waters. When coral die, the entire marine food chain is harmed, the WMO said.

In addition, atmospheric carbon dioxide (CO2) levels reached 400 parts per million (ppm) in 2015, the WMO said. That figure means there were 400 molecules of carbon dioxide in the air per every million air molecules. The 400 ppm threshold is high in contrast with the past 800,000 years, when CO2 levels fluctuated between about 170 ppm and 280 ppm, Michael Sandstrom, a doctoral student in paleoclimate at Columbia University in New York City, previously told Live Science.

The Paris Agreement, a U.N. climate treaty, addresses how to countries can decrease their emissions of CO2 and other greenhouse gases. The agreement is vital as it encourages the world to tackle "climate change by curbing greenhouse gases, fostering climate resilience and mainstreaming climate adaptation into national development policies," Taalas said. [Earth in the Balance: 7 Crucial Tipping Points]

2017 trends

Not everything made it into the 2016 report. New studies show that the ocean heat content may have increased more than previously thought, and early data suggests that there is no easing in the rate of increase for atmospheric CO2 concentrations, the WMO said.

"Even without a strong El Niño in 2017, we are seeing other remarkable changes across the planet that are challenging the limits of our understanding of the climate system," David Carlson, the World Climate Research program director, said in the statement. "We are now in truly uncharted territory."

For instance, the Arctic has had three "polar heat waves" this winter, Carlson said. These heat waves are alarming because sea ice, which usually refreezes during Arctic winters, is already at record lows compared with the past few years, he said.

What's more, changes in the Arctic and melting sea ice are causing a shift in wider oceanic and atmospheric circulation patterns, the WMO said. These changes are affecting the jet stream, the fast-moving band of air that regulates worldwide temperatures, and are already influencing weather patterns around the planet, the WMO said.

For example, parts of Canada and the United States were unusually balmy this year, while other regions, including the Arabian Peninsula and northern Africa, were unseasonably cold in early 2017.

In South Africa, the city of Pretoria sizzled at 108.8 F (42.7 C) and Johannesburg reached 102 F (38.9 C) on Jan. 7 — temperatures that were at least 5.4 F (3 C) higher than previous all-time records for those sites, the WMO said.

In February, the United States broke or tied more than 11,700 warm temperature records, the U.S. National Oceanic and Atmospheric Administration said. Down Under, where the seasons are flipped, parts of Australia had prolonged and extreme heat in January and February, and broke many new temperature records, the WMO said.

Original article on Live Science.

When Hurricane Nicole formed in the Atlantic Ocean right on the heels of Hurricane Matthew, which tore across Haiti and the Bahamas last week before lashing the southeastern United States, it was the first time on record that two major Atlantic hurricanes have occurred in the month of October. But these rare, back-to-back hurricanes may be an early sign of worse weather to come if La Niña climate conditions take hold across the globe, according to weather scientists.

Hurricane Nicole battered Bermuda yesterday afternoon (Oct. 13) with torrential rain and winds of up to 130 miles per hour (209 km/h), causing widespread property damage and leaving thousands of homes without power. The storm is now moving northeast across the Atlantic, away from Bermuda, and is expected to become a post-tropical cyclone tomorrow (Oct. 15), according to an advisory posted today (Oct. 14) at 11 a.m. ET (1500 GMT) by the National Hurricane Center (NHC).  

It was the second major hurricane to make landfall in the western Atlantic within five days, and the first time that two major hurricanes of Category 4 or Category 5 have formed in the Atlantic in October since record keeping began in 1851. [See Photos of the Tropical Storms and Hurricanes of 2016]

On Oct. 4, as Nicole strengthened over the ocean and Matthew made landfall in Haiti, the storms were the first large hurricanes — above Category 2 — to occur at the same time in the western Atlantic since 1964, according to the NHC.

The twin hurricanes may herald a much stormier time in the Atlantic, after a few years of relatively low hurricane activity, said Kevin Walsh, a professor of tropical meteorology at Australia’s University of Melbourne, who has watched the development of Matthew and Nicole over recent weeks. 

"We know during El Niño years in the Atlantic you get usually suppressed numbers of tropical cyclones — and of course El Niño is all over now, and we may or may not be moving into a mild La Niña," Walsh told Live Science. "But, if a big La Niña does actually set in, then it's quite possible that we could have increased hurricane numbers in the Atlantic."

The return of La Niña

El Niño and La Niña are the opposite phases of the El Niño Southern Oscillation (ENSO) cycle, caused by fluctuations in temperature between the ocean and the atmosphere in the tropical zones of the central and eastern Pacific Ocean, according to the National Oceanic and Atmospheric Administration (NOAA).

Each phase of the ENSO cycle can have different effects on the climate in different parts of the world. They usually last from nine months to a year, but some persist for several years, like the latest El Niño phase from 2011 to 2015, NOAA said.

If the oceans and atmosphere over the Pacific Ocean are now entering a prolonged La Niña phase, then hurricanes in the Atlantic Ocean are likely to become more common the longer it lasts, Walsh said.

"The only thing that it really depends on is how long the La Niña hangs around — and we don't know that at present, so it's a bit soon to be trying to predict for the Atlantic next year," he added. [A History of Destruction: 8 Great Hurricanes]

Tropical Storm Matthew first formed in a relatively normal way off the African coast in late September. The storm gained strength as it tracked across the Atlantic toward the Caribbean, where it rapidly intensified into a Category 5 hurricane on Sept. 30.

But Tropical Storm Nicole took a strange route across the Atlantic Ocean after it formed in early October, and meteorologists predicted more than once that the storm could disappear entirely.

"It is a bit unusual, partly because it's done a sort of funny loop-de-loop in the middle of nowhere, and then become quite strong after that," Walsh said.

Growing a hurricane

The way Hurricane Nicole lingered over the Atlantic likely increased its chances of becoming a stronger hurricane, Walsh said.

For example, the storm may have intensified after running into an area of very warm sea temperatures, or when atmospheric conditions turned more favorable for hurricane formation, he added.

Walsh also noted that an uncommon number of major hurricanes have hit Bermuda in recent years, although the region often endures several tropical storms each year.

"It's pretty rare for a hurricane to strike Bermuda directly, but that's happened a lot in the last few years," he said.

Only seven major hurricanes have passed within 40 nautical miles (74 km) of Bermuda since record- keeping began in 1851, but in 2014, the islands were hit by two hurricanes only six days apart: Hurricane Fay on Oct. 12, and Hurricane Gonzalo on Oct. 18.

Hurricane Fay was a Category 1 storm when it made landfall, and Gonzalo had weakened from a Category 4 storm to a Category 2 before it struck the island, but the combined effect of the two hurricanes just days apart resulted in heavy damage and disruption.

For now, the National Hurricane Center reports no "imminent tropical threats" in the Atlantic basin: no tropical storms or depressions that show the potential to develop into a hurricane.

But more than a month remains before the official end of this year's Atlantic hurricane season, on Nov. 30 — and until then, scientists and storm watchers will be keeping a keen eye on the tropics.

Original article on Live Science.

Australia's Great Barrier Reef corals are in trouble.

The northern part of the world's largest coral reef ecosystem is experiencing "the worst mass bleaching event in its history," according to a statement released Tuesday (March 29) by the Australian Research Council.

Documented by the National Coral Bleaching Taskforce (NCBT) in aerial surveys, observations of more than 500 coral reefs spanning 2,485 miles (4,000 kilometers) showed that the majority of reefs were undergoing extensive and severe bleaching.

"Almost without exception, every reef we flew across showed consistently high levels of bleaching, from the reef slope right up onto the top of the reef," said Terry Hughes of the NCBT, calling the surveys "the saddest research trip of my life." [Worst Coral Reef Bleaching on Record for the Great Barrier Reef | Aerial Video]

Bleaching happens when corals are exposed to stresses such as warmer-than-average waters for prolonged periods of time. The corals respond to the stress by expelling the algae that provide them with their color, which makes the corals look like they've been bleached white. Bleaching can be fatal for corals if the stress is too intense, or if it continues for too long and the algae are unable to recolonize them.

Ecosystem at risk

Australia's Great Barrier Reef (GBR) covers 134,364 square miles (348,000 square kilometers), making it larger than the U.K., Switzerland and the Netherlands combined, according to the Great Barrier Reef Marine Park Authority. Recognized as a World Heritage Area in 1981, the reef contains 400 types of coral and hosts 1,500 types of fish and 4,000 mollusk species, as well as other marine life such as large green turtles and dugongs ("sea cows").

The GBR experienced bleaching events in 1998 and in 2002, but the current mass bleaching is much more severe, experts are saying. Rebecca Albright, a marine biologist with the Carnegie Institution for Science in Washington, D.C., has studied the GBR since 2011. Albright told Live Science that 95 percent of the GBR's northern reefs are currently showing signs of extreme bleaching, compared with 18 percent that experienced bleaching in 2002.

Even the more robust corals are affected, Albright said, another sign that this event is particularly serious. She cautioned that it's still too early to assess the long-term impacts of bleaching on the corals, though estimates of coral mortality anticipate losses of about 50 percent.

Two factors are responsible for stressing the corals, Albright said: climate change, which is driving ocean temperatures upward, and a strong El Niño  — a cyclical climate event associated with warmer-than-average sea surface temperatures in the tropical Pacific. And with El Niño conditions expected to extend through 2016, that doesn't bode well for the corals' recovery.

"Corals are sensitive to not only the anomaly in temperature — how high it goes — but also the duration of that exposure," Albright told Live Science. "This kind of perfect storm of all these factors coming together makes this a catastrophic scenario right now." [Images: Colorful Corals of the Deep Barrier Reef]

A global event

But what's happening to the GBR is only part of the picture. A global bleaching event prolonged by El Niño is currently underway — "the longest coral die-off on record," according to a statement released by the National Oceanic and Atmospheric Administration (NOAA) on Feb. 23.

Mark Eakin, coordinator of the NOAA Coral Reef Watch program, told Live Science that the event, which began in 2014 in the Pacific, could linger through 2017.

"We consider it a global bleaching event if it's widespread in all three of the major ocean basins — Indian, Atlantic and Pacific," he said. Eakin described current reports of bleaching that extend over half of the Southern Hemisphere, with severe bleaching in New Caledonia, Fiji and southern Indonesia, as well as in the GBR.

Even fast-growing corals take decades to develop, so damaged reefs will need time before they're restored to their former level of health, Eakin said.

And recovery time may be in short supply. Global bleaching events have been expanding their reach and increasing in severity since the first event was documented in 1998, Eakin told Live Science.

"We’re seeing prolonged high temperatures that cause bleaching coming back repeatedly. We're seeing areas that have seen high temperatures for two to three years in a row. There's no time for corals to recover," he said.

The 1998 global bleaching event was associated with a strong El Niño — the strongest on record — but as ocean temperatures rise, even a mild El Niño can trigger a devastating effect on the world's corals. And the global bleaching event that's underway right now began in 2014, before the current El Niño was active, Eakin said.

For the GBR, in spite of the extreme bleaching there may yet be some hope for its recovery. The upper part of the reef that sustained the most damage was in very good shape beforehand, which should improve its prospects for "bouncing back," according to Albright.

"And the lower two-thirds of the GBR is still in very good shape — not a lot of bleaching in those areas. So a lot of people are holding on to that as another piece of hope," Albright said.

"It’s really just a matter of whether or not we get another bleaching event in the next 10 years that would impede recovery," she added.

Follow Mindy Weisberger on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

From crippling drought in southern Africa to a record number of February tornadoes in the U.S. Southeast, an exceptionally strong El Niño has been making headlines around the globe as it tampers with the world’s weather.

While the event has begun its slow decline, those wide-ranging impacts will continue to be felt for weeks and months to come — good news for those in California, who need El Niño-fueled rains, but bad news for the many areas, like Indonesia, which is suffering from deep drought, food and water shortages, and wildfires.

Already this year, El Niño-related weather has cost billions of dollars in damage and left some 100 million people facing food and water shortages.

Through the interactive graphic below, Climate Central takes a look at how this major climate pattern typically influences the world’s weather, what it can mean for societies in the areas it affects, and what has actually been happening with this particular event, which ranks amongst the strongest on record. After all, no two El Niños are the same. For instance, while Southern California was drenched during the 1997-1998 El Niño, it has remained disconcertingly dry this time around.

First, the big picture: El Niño is most known for shifting a large pool of warm ocean waters from the western to the central and eastern tropical Pacific. That shift changes where heat is pumped into the tropical atmosphere, disrupting its typical circulation patterns. Those local disruptions cause a domino effect through the global atmosphere that can alter weather thousands of miles away.

There are two main circulation patterns that are affected. All around the tropics is a pattern of rising and sinking air — like a vertical loop — called the Walker Circulation. The rising air corresponds to areas of unsettled, rainy weather, while the sinking air creates a stable, dry clime. Normally in the tropical Pacific, a major area of rising air is found over the western portions, where the warmest waters are found. With the eastward shift from El Niño, that rising air (and its sinking counterpart) move eastward as well. This displacement shifts the other branches of the Walker Circulation around the tropics, pushing wetter weather over areas that might normally be dry and vice versa. These areas typically see some of the strongest impacts from El Niño because they are in a region more directly linked to it.

The changes in the Walker Circulation in turn cause shifts in another looping pattern called the Hadley Circulation that runs north-to-south to the Walker’s east-to-west. And those changes in the Hadley Circulation can affect the subtropical jet stream — an area of fast-moving air that guides storms — in both the Northern and Southern hemispheres. This is how El Niño can affect regions far from the tropics.

The changes in these main circulation patterns interact with other factors, like seasonal monsoons and other major climate patterns, which is why none of the typical impacts associated with El Niño are guaranteed. It merely shifts the odds in their favor.

Let’s dive in for a closer look at some of the local and regional impacts and what has actually played out this year:

Southeast Asia

Indonesia, and Southeast Asia more broadly, is one of the areas most directly impacted by El Niño. The eastward shift in the Walker Circulation means the normal area of rising air and rainy weather is shifted eastward as well, leaving the Indonesian area high and dry during much of the year. This can lead to drought that can cause water shortages and crop and livestock losses from dried up fields. Those losses then lead to food shortages and rising prices, and can also increase the odds of large wildfires.

This year has seen major drought grip Indonesia, Vietnam, Thailand, the Philippines and much of the U.S. Pacific Island territories. In Indonesia there were major delays in the planting of the rice crop, leading to concerns over food shortages. And when farmers set their usual fires to clear brush for planting, the dry conditions caused many to burn out of control, causing one of the biggest burn years on record and leading to a pall of smoke over the region. In Vietnam, drought has led to salinization issues in the Mekong Delta region, home to some 20 million people and a major rice growing area.

Drought has caused the Republic of the Marshall Islands and the Federated States of Micronesia to declare states of emergency, with some islands enacting water rationing and having to have water shipped in.

Australia

That same eastward shift of storm activity tends to bring drier conditions to northern Australia during the Southern Hemisphere summer and more broadly to the east in the winter. It also tends to bring warmer summer weather to southeast Australia because of the larger mass of stable, subsiding air in place. During El Niño years, drought and wildfires also become a concern here.

So far this year, Australia has seen a mixed bag of El Niño impacts. While dry conditions have been in place in much of the usual areas, some of the inland regions of the eastern part of the country actually had fairly normal rains. That may be due to exceptionally warm Indian Ocean waters providing more moisture to storm systems. The southeast has seen some major heat waves, though, with temperatures sometimes climbing above 100°F (40°C). The hot and dry conditions have helped create more favorable wildfire conditions, with several burning in Victoria this year. One of the worst destroyed 116 houses around Christmas.

India

India also tends to see drier weather during the Northern Hemisphere summer because the changes to atmospheric circulation patterns delay the onset of the seasonal monsoons. Monsoon rains are critical to supplying water for drinking and agriculture, and El Niño years tend to see drought develop in parts of India.

This summer, rainfall in India was 14 percent below normal and reservoirs were down by 30 percent, according to a United Nations report. That led to shortages of drinking water in some areas and caused rice, corn and soybean fields to dry up, setting off worries for food shortages and inflated food prices.

El Niño can lead to wetter weather in southern India, which also happened this year, with torrential rains that causedmajor flooding in the area around Chennai.

Pacific Ocean

Moving back out into the Pacific Ocean, the warmer ocean waters can cause bleaching of coral reefs, killing them. This event has seen one of the longest global bleaching events ever recorded, according to experts.

March Miracle? El Niño-Fueled Storms Return to California Longest Global Coral Bleaching On Record Isn’t Over Yet NOAA and NASA Team Up to Investigate Strong El Niño

Warmer ocean waters in that area also provide more fuel for hurricanes in the central and eastern Pacific Ocean basins. The atmospheric changes El Niño brings also mean more favorable winds for storm formation. This year sawabove-normal hurricane activity in the region, including the strongest storm ever directly measured in the Western Hemisphere. Hurricane Patricia, which had winds that clocked in at 200 mph, hit the west coast of Mexico, though its effects were mostly confined to less populated areas.

South America

Parts of South America are also more directly affected by El Niño. The warmer ocean waters off its west coast tend to bring warmer weather to coastal areas during the Southern Hemisphere winter. Those waters also make more moisture available to storms. Combined with changes to storm tracks linked to atmospheric circulation changes, this can mean wetter winter weather for central Chile. Several rounds of storms during this event had some benefits, bringing moisture to a region in drought and snows to ski resorts. But the rains also brought flooding and mudslides. A rare storm event in March saw parts of the bone dry Atacama Desert receive a year’s worth of rain in just one day. The Copiapó River — dry for nearly 17 years — filled to overflowing and flash floods swept through several towns. Come spring, that influx of water led to a surreal bloom of flowers across the desert that tends to coincide with rainy El Niño years.

The chain of changes to the Walker and Hadley circulations also tends to bring rainier weather to an area that includes Paraguay, northern Argentina, part of southern Brazil and Uruguay during the Southern Hemisphere summer. In December and January, heavy rains caused the worst flooding in the region in 50 years, displacing more than 200,000 people. The Paraguay River in Asunción reached more than 16 feet above its normal level in December. Thousands of acres of cropland were inundated and concerns were heightened for the spread of mosquito-borne disease like dengue fever and the Zika virus.

In northern Brazil and other countries in the north of South America, the eastward shift of the Walker Circulation brings sinking air and drier conditions. Those come with the usual tendency toward drought, water shortages and crop and livestock losses. Drought and those follow-on impacts have been recorded in northeastern Brazil, an area already vulnerable due to poverty and remoteness.

Some recent research has suggested that the exceptional heat and drought in the area may actually have helped fuel the rise of the Zika virus epidemic in the region. Heat promotes the growth of the mosquito that carries the disease, and during drought, residents tend to store water in containers in which the mosquitoes can breed.

Central America and the Caribbean

Further north, drier weather also tends to grip Central America and the Caribbean for the same reasons as northern South America. The area that spans Guatemala, Nicaragua, Honduras and El Salvador is experiencing one of its worst droughts in decades, according to the European Commission. Major crop losses have caused huge financial hits to farmers and left some 3.5 million people facing food shortages, the agency reported.

In the eastern Caribbean, 2015 was the driest year on record and led to water restrictions on many islands, including St. Lucia, St. Kitts, Barbados and Puerto Rico. Diminished water supplies also led to crop losses in the Dominican Republic, Haiti and other areas. As of August,Antigua had no surface water supplies, and by October it was using 100 percent desalinated water.

The subsiding air that leads to drought also tends to help tamp down on hurricane formation in the region. This year saw a below-average Atlantic hurricane season.

United States

Not far away, though, El Niño brings the opposite conditions to Florida. The shifts in the Hadley Circulation affect the subtropical jet stream that crosses the U.S., pushing it southward and making it extend further eastward. This puts Florida in a prime location for storms during the winter months, which is normally its dry season. It also ups the odds for tornadoes thanks to the added energy from the jet stream.

Florida did have a wetter than normal winter this year, and its southern tip had its wettest year on record. It also saw 18 tornadoes in January and February, compared to the seven it usually sees during those months.

While tornado activity may typically rise in Florida in El Niño years, it is usually tamped down in the area of the central U.S. known as Tornado Alley. The more southward jet blocks the moisture from the Gulf of Mexico that is key to fueling spring storms there. An experimental seasonal tornado forecast favors a below-average tornado seasonthere this year.

The tweak to the jet stream also tends to favor wetter weather over Southern California — much needed this year after four years of deep drought. While storms have been hitting California, they have mostly affected the northern portions of the state because the jet stream has been slightly further north than is typical during an El Niño. The rains shut off almost completely in February, bringing hot and dry weather to the state, though storms have since returned and look to bring at least some rain to Southern California.

Across the northern tier of the U.S., from the Northeast all the way up into eastern Alaska, El Niño tends to favor warmer than normal conditions. That has indeed been the case this year, with nearly all northern states recording one of their top 10 warmest winters. Alaska saw its second-warmest winter in the books, which has contributed to a lack of snow in varied locations there. That dearth of snow can have ecological impacts and promote the spread of invasive species. El Niño wasn’t the only reason Alaska was warm, though, as the Arctic more broadly was exceptionally warm this winter.

Africa

And, finally, across the Atlantic in Africa, some of the populations most vulnerable to El Niño’s impacts are found.

In the Southern Hemisphere summer, the eastward shift of the Walker Circulation leads to rising air over Kenya, southern Somalia and southern Ethiopia, which can enhance seasonal rains. Increased rains can lead to flooding, mudslides and outbreaks of diseases.

Heavy rains in the area began in late October, inundating villages and agricultural lands. By January, more than 100,000 people had been displaced and 112 killed, according to the International Federation of Red Cross and Red Crescent Societies. Authorities are concerned about the spread of both waterborne diseases, such as cholera, and mosquito-borne ones, particularly Rift Valley Fever, which tends to occur in years with unusually heavy rainfall.

Just to the north, in Ethiopia and Somalia, El Niño has brought dry conditions that have exacerbated a drought and led to crop failures and widespread livestock deaths, according to the United Nations Food and Agriculture Organization.

Drought has also gripped large parts of southern Africa, particularly the northeast of South Africa, Mozambique and Zimbabwe. The changes to the Walker and Hadley circulations interact with the normal monsoon there and tend to suppress monsoon rains, leading to drought, crop losses and food and water shortages.

Severe rainfall deficits this year have lead to widespread drought that has decimated the maize crop, costing hundreds of millions of dollars in losses. Zimbabwe declared a state of disaster as some 2.5 million people are in need of food aid. South Africa, normally an exporter of corn, is expected to have to import it this year to feed its citizens.

The drought has also severely reduced the flow of rivers that feed hydropower dams, leading to power rationing and even blackouts in the region. The flow down the majestic Victoria Falls has reached a 30-year low.

While El Niño has shown signs in recent weeks that it is beginning to weaken, it will likely be late summer or early fall before it fully dissipates. Its weather affects around the world are expected to continue for several more months, and the impacts of that weather could reverberate for years to come, making it one for the record books.

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This article was originally published on Climate Central.

Thousands of dead seabirds have washed up on Alaskan shores over the past nine months. And while a dead bird washing ashore is a fairly common occurrence, these large numbers are leaving scientists concerned and confused.

Nearly 8,000 common murres (Uria aalge) were found along the shores of Whittier, Alaska, in early January. Over the New Year's holiday, Alaska experienced four days of gale-force winds from the southeast that resulted in dead birds washing ashore, said Robb Kaler, a wildlife biologist for the Alaska branch of the U.S. Fish and Wildlife Service (USFWS). Scientists have known for some time that the key to surviving strong storm winds is having an energy reserve, according to an expert at Tufts University, and Kaler and his colleagues think that the common murres were not finding enough food this season, which may be why so many didn't make it through the storm.

In cases like these, experts typically measure the number of dead birds per kilometer, said Julia Parrish, a professor in the School of Aquatic and Fishery Sciences at the University of Washington in Seattle and executive director of the Coastal Observation and Seabird Survey Team (COASST), which is one of the organizations studying areas where these birds are washing ashore, alongside the USFWS and the U.S. Geological Survey National Wildlife Health Center (NWHC). For the Whittier survey, the final measurements came to approximately 4,600 birds per kilometer, Parrish told Live Science. [5 Mysterious Animal Die-Offs]

The common murre is "one of the most abundant and widespread seabirds in Alaska," Kaler told Live Science in an email. While other dead seabirds are being reported on Pacific shorelines, current reports indicate that about 99 percent of the animals are common murres, Kaler said.

Seeing a dead seabird on the beach is not altogether unusual, especially during September and October, when the birds are leaving their breeding colonies, Parrish said. However, dead common murres started showing up in Alaska in March.

"This is really weird, because that is the beginning of the breeding season," Parrish said. "That's when [seabirds] are [usually] fat and sassy."

What's going on?

So far, the NWHC has examined 100 bird carcasses, and most of the birds seem to have died due to starvation, Kaler told Live Science.

"While we know murres are starving," Kaler said, "we do not understand the mechanism."

There is a chance that saxitoxin, a toxin related to paralytic shellfish poisoning, or domoic acid, a toxin that causes amnesic shellfish poisoning, could be responsible for some of these deaths, he said. But both of these toxins are difficult to detect in birds that have nothing in their stomachs or gastrointestinal tracts, which was the case with most of these animals, Kaler said.

In the past, seabird die-off events — in which thousands of birds die in a short period of time — have been associated with strong El Niño events, Kaler said. In 1993, there was another die-off of common murres recorded in the northern Gulf of Alaska, where scientists found about 3,500 dead or dying common murres along the shoreline over a period of six months. Scientists calculated that over that period, about 10,900 bird carcasses actually made it to shore, according to a 1997 study published in the journal Marine Pollution Bulletin.

Because researchers were able to monitor only a small fraction of the beaches in Alaska, that study's scientists projected that the actual final death count in 1993 was at least 120,000 birds.

With this most recent event, "[w]e assume the die-off is connected to one of the largest oceanographic-atmospheric events, known as 'The Blob,'" Kaler said. This event is the presence of a large area of water that falls well above the average temperature usually observed in the North Pacific, he said. "We do not know how [that] this relates to El Niño or climate warming, but we believe they are factors," Kaler said.

The USFWS also noted in a recent bulletin that common murres have turned up at locations as far inland as Fairbanks, Alaska, where the birds have been seen swimming in rivers and lakes. Wildlife biologists consider this to be unusual behavior, since common murres are seabirds and so don't usually show up so far inland, Parrish told Live Science.

Additionally, while the die-off has been most visible in Alaska, similar events affected seabird populations in Washington, Oregon and California during the months of September and October, Parrish said.

What does this mean?

The behaviors of seabirds are often indicators of what is happening in the marine system, said the U.S. Fish and Wildlife Service. Current estimates of the common murre death toll in the recent die-off have suggested that more than 100,000 birds have probably died over the past nine months, and dead birds are likely to continue showing up through the spring, Kaler said.

It is important to note that this high death count doesn't mean that common murres are in danger as a species. There are an estimated 2.8 million common murres in Alaska, Parrish said. This means that current estimates of the die-off account for only approximately 3 percent of the total common murre population in the state.

That's not to say that the appearance of large numbers of dead birds on beaches isn't of concern, Parrish said. Scientists are speculating that this event indicates a species struggling to deal with altered circumstances, he said.

"When there are heat waves during the summertime, you always hear about mortalities in the inner city [from people who don't have air conditioning] and [so] they just have to deal with" the heat, Parrish said. "None of these birds have air conditioning."

Follow Elizabeth Newbern @liznewbern. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

A massive winter storm that is expected to bring snow and ice to the eastern United States in the next 48 hours dwarfs the central part of the country in a new satellite image.

The National Oceanic and Atmospheric Administration's GOES-West satellite spotted this cloudy view of the large storm near the Gulf Coast today (Jan. 21) at 10 a.m. EST. (The satellite photo also spied a separate storm swirling over the Pacific Ocean.)

The NASA-NOAA Suomi NPP satellite captured another view of the looming winter storm yesterday (Jan. 20) at 2:30 p.m. EST, showing clouds and snow cover stretching from northern Texas into the Great Lakes states. The low-pressure system, which originated in the Eastern Pacific, is headed toward the mid-Atlantic states. The National Weather Service is warning of a potentially "crippling" snowstorm in those areas tomorrow and Saturday. [VIDEO: Watch the Developing Storm from Space]

Much of the East, from as far south as northern Georgia to as far north as New York City, is under weather alert, ranging from winter storm warnings in eastern Tennessee, Kentucky and western North Carolina to a blizzard watch in Washington, D.C, Baltimore and up the I-95 corridor through New Jersey.

"At this moment, this still looks like it's going to be northern Virginia and Maryland's most memorable snow," said David Robinson, the state climatologist of New Jersey. "A question remains just where exactly the heaviest snowfall totals will fall, just where the strongest winds will be and where the coastal flooding will be worst."

Volatile winter

The storm will track across the Tennessee Valley tonight and Friday, ultimately hitting the mid-Atlantic states Saturday, with lessening snow expected by Sunday. Storms like the one bearing down on the eastern United States typically have a band of heavy snowfall about 100 miles (161 kilometers) wide, Robinson told Live Science. North of this band, precipitation peters out, leading to low overall totals. South of this band, temperatures are warm enough that snow turns to rain.

"This is a multifaceted nor'easter, as they all tend to be, laden with strong wind and impacts on the coast and heavy precipitation of one form or another," Robinson said.

El Niño's influence may also be at play, Robinson said. The storm "fits the pattern of volatility that we often see in weather, really across the country, during an El Niño winter," he said.

The winter of 2015-2016 has so far been marked by an active storm pattern in the western United States, with unseasonably warm temperatures and unusual midwinter thunderstorms in the South. In late December and early January, the Mississippi River flooded to levels not seen since 1993, thanks to heavy snows and rainfall in the western and central parts of the country. A rare December tornado outbreak from Indiana to Alabama killed 13 people between Dec. 23 and Dec. 25.

Meanwhile, warm temperatures made Christmas a balmy holiday for many on the East Coast. New York City experienced its warmest Christmas on record, with temperatures reaching 66 degrees Fahrenheit (19 degrees Celsius). On Christmas Eve, the mercury hit 72 degrees F (22 degrees C) at LaGuardia Airport in New York, breaking a 76-year record. The previous high temperature that day, according to NOAA's National Centers for Environmental Information, was 63 degrees F (17 degrees C).

Ice, wind and floods

If volatility is a feature of El Niño winters in the United States, so is an active East Coast storm track, Robinson said.

"We have seen coastal storms aplenty during El Niño winters," he said. Those storms don't always translate to snow, though, he added. Some mid-Atlantic El Niño years have been virtually snow-free, while others have seen large snowstorms.

Regardless of snow totals, the incoming storm is likely to be a major event, meteorologists say. Forecasts predict water levels 3 to 4 feet higher than normal along the New Jersey coast down into Delaware, Robinson said, and winds could gust more than 60 mph (96.5 km/h).

Washington, D.C., and the surrounding area is under a blizzard warning, with about 24 inches (60 centimeters) of snow expected for the capital city and 24 to 30 inches (60 to 76 cm) in the western suburbs, according to the National Weather Service. Gusty winds, ice and up to a foot (30 cm) of snow are expected in Kentucky. Detailed regional weather advisories and forecaster discussions can be found at http://www.weather.gov/.

Follow Stephanie Pappas on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

It’s not often that an official hurricane forecast uses the word “surreal,” but that was the case late Monday as Tropical Storm Pali improbably became Hurricane Pali, the earliest hurricane ever recorded in the Central Pacific.

The out-of-season storm has benefited from unusually favorable conditions largely linked to the strong El Niño that also helped boost storm activity to record levels during the main storm season.

The official hurricane season in this basin is May 15 to Nov. 30, but when conditions are right, storms can, and have, formed outside of that typical timeframe. But winter storms are still rare, with only three having ever been recorded in the January to March period.

Pali became a tropical storm on Jan. 7, aided by El Niño-driven warm waters, as well as winds linked to El Niño and another feature called the Madden-Julian Oscillation. Those winds helped provide the storm with spin; most tropical cyclones spin because of the influence of the Coriolis force, but this force is very weak near the equator, which is where Pali formed.  

#Pali is the earliest hurricane on record in the North Central Pacific, breaking old record set by Ekeka (1/30). pic.twitter.com/VUiPC8EM5w

— Philip Klotzbach (@philklotzbach) January 12, 2016

After it formed, forecasters expected the storm to weaken, and it did, for a time.

“It got down to a minimal tropical storm strength,” Derek Wroe, a forecaster with the Central Pacific Hurricane Center in Hawaii, said.

But then, upper level winds that had been tearing at the storm relaxed “and then all of a sudden it redeveloped,” Wroe said.

On Monday, it strengthened sufficiently to reach hurricane status, leading the forecaster on duty to remark in the official forecast: “It is rather surreal to be saying this in January ... but the satellite presentation of Pali has continued to improve today.”

Pali is now the earliest hurricane to form in a calendar year, beating out Hurricane Ekeka, which became a hurricane on Jan. 30, 1992.

“Yet another record to stack on the ever-growing pile of recent records due in large part to the ongoing strong El Niño,” the forecaster said.

Pali is expected to hang on to its hurricane status through Thursday as it tracks southward toward the equator — a very unusual path for a storm to take in the region and yet another odd feature of the storm. Tropical cyclones normally head westward or northward in this region, Wroe said. “Due south like this is extraordinarily rare.”

The storm isn’t a threat to any land areas, so it can remain a scientific curiosity.

“It’s going to be interesting to watch what happens,” Wroe said.

Originally published on WXShift.com.

A venomous sea snake washed up on a Southern California beach recently, striking fear in the hearts of beachgoers but eliciting excitement from the scientists who study these marine reptiles.

The stranded snake, which was dead when it was discovered on Dec. 12, was a yellow-bellied sea snake (Pelamis platura), the most widespread marine snake in the world. But despite its wide range of habitats, this snake isn't usually observed in the waters off the coast of Southern California, as it tends to keep to the warmer waters just south of that coastline, closer to Baja California, Mexico. Yet, in 2015, two of these critters washed up on California beaches, leading many to wonder why the snake is venturing outside its normal habitat.

"North of the tip of Baja [California], we have only five documented observations of this snake ever. Prior to this year, we only had three," said Greg Pauly, assistant curator of herpetology at the Natural History Museum of Los Angeles. The last time someone saw a yellow-bellied sea snake in California was in 1972, when one of these snakes washed ashore in San Clemente, he told Live Science. [7 Shocking Snake Stories]

So what is bringing the yellow-bellied sea snake to the shores of California? Pauly said the snake has only been observed in the region during El Niño years, or years in which sea-surface temperatures in the equatorial Pacific Ocean (which includes the waters just south of Southern California) are unusually high. What might be happening is that, as sea-surface temperatures rise and cause ocean currents to change as a result, the yellow-bellied sea snake moves a bit farther north, outside its usual haunting grounds, Pauly said.

However, as ocean temperatures off the coast of the western U.S. begin to cool during the winter months, the snakes may get sick or find themselves without enough food to survive, he said.

"As their health starts to decline, they get washed up onto these beaches — either because they're in poor health or because they already died and then get washed up after they're dead," Pauly said.

Folks who fear the venomous bite of the yellow-bellied sea snake may not lament that these snakes aren't alive when they hit dry land, but the truth is that P. platura doesn't pose much of a risk to humans, provided the humans who encounter them don't try to touch the snakes, Pauly said. While yellow-bellied sea snakes deliver a neurotoxin-packed bite, their venom is designed to take down small fish, not relatively large humans. (Their fangs and mouth size are also not built for biting large prey.) There have been no known human fatalities from envenomation by one of these snakes, Pauly noted.

Pauly called the snake's appearance in Southern California "exciting" because these animals are so rarely observed in the U.S. The appearance of two such snakes in one year is "unprecedented" (and also "pretty amazing"), he said.

Yellow-bellied sea snakes aren't the only marine creatures to come ashore since the onset of El Niño in 2015. In June, sea slugs, or sea hares — which look a lot like big, purple blobs — started appearing on the beaches along Oakland's East Bay in California. That same month, thousands of tiny red crabs, or tuna crabs (Pleuroncodes planipes), washed up on beaches in Orange and San Diego counties in California. But all of these critters, which typically inhabit warmer waters farther south, are likely showing up on beaches in the U.S. for the same reasons, Pauly said.

"There are a couple of things going on, most likely: We're seeing this really strong El Niño, and because of these warmer sea-surface temperatures, a lot of species are showing this response [of coming north], Pauly said. "El Niño is certainly one culprit. But there are a couple of other things going on with the sea-surface temperatures right now."

Specifically, there's something called the Pacific Decadal Oscillation (PDO), which means that the Eastern Pacific (including the water off Southern California) is getting warmer. And then there's the "blob."

"The blob is actually three different blobs — some really unusual areas where really big chunks of the ocean off the coast of North America are much warmer than usual," Pauly said. "And normally, what happens is that sea-surface temperatures cool during the winter months, but there are these three areas where the temperatures are staying warmer than normal by several degrees."

One of those blobs just happens to sit right off the coast of Southern California. Together with El Niño and the PDO, the blobs may be increasing sea-surface temperatures enough to encourage warm-water species — the yellow-bellied snake and its friends — to venture farther north than they normally would.

So what should you do if you see an unusual sea creature washed up on your local beach? That's simple, Pauly said: Take a picture. Then, send that picture to the Natural History Museum of Los Angeles (nature@nhm.org). Scientists there will be glad to see what you've stumbled upon. Just do yourself a favor and look, don't touch.

Follow Elizabeth Palermo @techEpalermo. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

El Niño is likely to strengthen by the end of the year, potentially bringing more precipitation than usual to much of the United States.

This year's El Niño is among the strongest since 1950, according to meteorologists. Already, the atmospheric pattern is among the top three since that time, according to the World Meteorological Organization (WMO).

The organization's latest update warns that peak three-month average surface water temperatures in the east-central tropical Pacific are more than 2 degrees Celsius (3.6 degrees Fahrenheit) above normal. El Niño is a climate pattern that brings warm water to the western shores of South America. This warm water is prone to evaporation, fueling a moister atmosphere that boosts Pacific hurricanes such as Patricia, the October storm that grew to be the most powerful tropical cyclone ever measured in the Western Hemisphere. [How El Niño Causes Wild Weather All Over the Globe (Infographic)]

However, the effects of El Niño are complex. While the southern half of the United States usually gets soggier with El Niño, some regions — including Hawaii, Australia, India and Brazil, among other places — become more prone to drought, according to the National Drought Mitigation Center at the University of Nebraska – Lincoln.

The current El Niño ranks among those in 1972-1973, 1982-1983 and 1997-1998 as one of the strongest on record, according to the WMO. Already, the effects are apparent.

"Severe droughts and devastating flooding being experienced throughout the tropics and subtropical zones bear the hallmarks of this El Niño, which is the strongest for more than 15 years," WMO Secretary-General Michel Jarraud said in a statement. El Niño typically reaches peak strength between October and January.

Predicting weather patterns in particular regions in this strengthening El Niño is difficult, however, because the pattern is only one of several that affect global weather. The tropical Atlantic sea surface temperature and the oscillations in temperature of the Indian Ocean play roles in determining temperature and precipitation as well, according to the WMO. The situation is further complicated by the backdrop of global climate change, which has melted Arctic summer ice and snow, and heated up the ocean surface.

"[T]his naturally occurring El Niño event and human-induced climate change may interact and modify each other in ways which we have never before experienced," Jarraud said. "Even before the onset of El Niño, global average surface temperatures had reached new records. El Niño is turning up the heat even further."

One 2010 study found that climate change may shift warm waters from the eastern equatorial Pacific to the central Pacific, which, in turn, could completely alter the atmospheric patterns El Niño brings.La Niña, a separate weather pattern that typically involves cooler-than-usual waters in the equatorial Pacific, may become more extreme with global warming, according to research released this year in the journal Nature Climate Change. Extreme La Niña events often occur after extreme El Niño events because El Niño releases heat from the ocean into the atmosphere, Wenju Cai, the author of that study and a climate scientist at the Commonwealth Scientific and Industrial Research Organisation in Australia, told Live Science at the time. The result is atmospheric circulation that cools the equatorial Pacific.

La Niña can cause drought in the southern United States and flooding in the areas that El Niño typically dries out, meaning that if this pattern of extreme El Niño to extreme La Niña sets up, the globe could be in for a wild ride over the next several years.

Follow Stephanie Pappas on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

With Halloween less than a week away, science nerds everywhere are scrambling to put the finishing touches on their costumes. But if you've waited until the last minute to throw an outfit together, don't worry. There's still time to assemble an appropriately geeky getup in time for this weekend's festivities. Here are a few science-themed ideas to get you started.

Dark matter

It's invisible, intangible, misunderstood and sometimes misrepresented. What is it? It's dark matter, of course. This nonluminous material (it doesn't produce any light of its own) is thought to make up about 27 percent of the universe, according to NASA.

A Halloween costume depicting dark matter can pretty much look however you want it to look, because no one knows what dark matter really is. But if you want people to get a general sense of darkness and mystery, here's what you'll need: black tights, a black shirt, black stockings (for your head) and a pair of black slippers. [Photos: The Best Science-Themed Halloween Costumes]

Adorn yourself in these articles of clothing, and then slink around the party, saying mysterious things like, "Are my axions showing?" Also, be sure to do a lot of unpredictable things, like grab people and hold them in one place (explain that dark matter was once believed to be a sort of "glue" that held galaxies in place) and then push them away (explain that astronomers are no longer sure that dark matter actually serves as an anchor for anything).

Doc Brown

It's October 2015, which makes a "Back to the Future"-themed costume most fitting this Halloween. If you're not familiar with the famous time-traveling trilogy, 2015 was the year in the future that Marty McFly visits in "Back to the Future Part II."

You could build a hoverboard and go as McFly, but if you want to embrace your inner mad scientist, then Doc Brown is the better option. You'll need just a few things to create the look: a lab coat, a Hawaiian shirt, frizzy hair (preferably white), and any old electronic device with an antenna or an enormous old cell phone.

To really sell this costume, keep your eyes wide open, and be sure to use the expression "Great Scott!" intermittently throughout the evening. Also, refer to all iPhones as flux capacitors (that's the gadget that enabled time travel in the movies).

Pluto & New Horizons

If you're attending a costume party this weekend with a significant other (or a baby), then you'll want to wear coordinating outfits. Luckily, there's a space-themed costume that's perfect for the occasion: Pluto the dwarf planet and the space probe New Horizons.

For the sake of accuracy, the larger person in the duo should be Pluto. To make the costume, just cut two large circles out of a piece of cardboard and color them to look like Pluto. Create straps using two pieces of ribbon and a stapler, and you'll be ready to go.

For the space probe, you'll need something that looks like a satellite dish (perhaps one of those cones from the veterinarian's office or a Styrofoam bowl). You can construct the metal frame inside the dish using silver-painted chopsticks or pencils. You'll also need to create a "solar panel" out of cardboard to attach to one of your arms. Wear yellow or wrap yourself in gold-tinted foil to complete the look, and then cozy on up to Pluto.

El Niño

El Niño: It isn't just the warm phase of the El Niño Southern Oscillation, a periodic climate cycle caused by variation in sea surface temperatures in the eastern Pacific Ocean. It's also the perfect costume for an outdoor Halloween party.

Transforming yourself into El Niño is easy because the effects of this warm-water phenomenon vary so greatly. In some places, El Niño is associated with warming sea surface temperatures (you could wear a bikini!), but it's also associated with increased sea ice in certain places (put on your full-body wet suit!).

One of the most widely known effects of El Niño is increased rainfall in some areas of the globe. If you relate to this, try carrying some water bottles around with you, and squirt them at your fellow partygoers. Everyone will love it, unless they hate it — in which case, put the water bottles down and dry people off with a towel. (El Niño is also associated with drier-than-average weather in certain areas of the world.)

Iron (Fe) Man

If you want to be a superhero and a science geek at the same time this Halloween, then the "Iron (Fe) Man" costume is perfect for you. To assemble your costume, find two large pieces of cardboard (one for your front side and one for your backside). Draw a large "Fe" (the atomic symbol for iron on the Periodic Table of Elements) on each piece of cardboard, and strap them onto your body to complete the look.

If no one understands your costume, it may be time to find nerdier friends.

A constellation

If the thought of being dark matter for Halloween sounds gloomy, then a constellation might be a better costume choice for you. To make this costume, assemble an all-black outfit and buy a package of large, plastic, glow-in-the-dark stars. Lay your black clothes down on a bed, and stick the stars to the clothes in the shape of your favorite constellation.

Orion, Cassiopeia, the Little Dipper — it doesn't really matter which one you choose; you're sure to be the star of the show.

Skeletorus

You could be a skeleton this Halloween, or you could be something so much better — a Skeletorus. If you're not familiar with this tiny arachnid, which was first discovered in Australia earlier this year, then do some quick reading before making your costume.

To create the spider costume, you can either purchase a skeleton shirt or make one yourself (Fiskars has good tutorials on how to make your own using a black T-shirt, a white T-shirt and some wax paper). Then, you'll need to make four spider legs (your two arms and two legs will serve as the other four legs) by stuffing black tube socks or stockings filled with crumpled-up newspaper and sewing or stapling them to the sides of your shirt.

To complete the look, you'll need oversize eyes — so get out your most fashionable sunglasses, and then go party.

Follow Elizabeth Palermo @techEpalermo. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

It's official: El Niño is back.

This winter is likely to be wetter and warmer than average, thanks to a strong El Niño brewing in the Pacific Ocean that will probably persist through the winter, forecasters said today (Oct. 15) during a news briefing.

"We won't be able to officially rank it until it peaks out and ends. But our expectation is that it will be amongst the three strongest," with the other strong El Niño events occurring in the 1997–98 and 1982–83 winter seasons, said Mike Halpert, the deputy director of the Climate Prediction Center, part of the National Oceanic and Atmospheric Administration (NOAA).

The strong subtropical weather pattern boosts the odds for rainfall and warm temperatures across the Southern United States and the Eastern Seaboard — including drought-stricken regions such as California and the Southwest.

But even if California is inundated with rain, the state's water woes probably won't be eliminated in one season, the experts said. [Infographic: How El Niño Causes Wild Weather Across the Globe]

El Nino brewing

El Niño weather patterns occur when warm water from the western tropical Pacific Ocean shifts toward the equatorial coast of South America, nudging tropical storms eastward. Because moisture-laden air causes thunderstorms, and because the greatest amount of water evaporates from the oceans in the warm, tropical areas, El Niño weather patterns tend to bring high-precipitation thunderstorms and warmer weather to the United States. El Niño and its counterpart, La Niña, are part of the El Niño-Southern Oscillation, or ENSO, cycle.

This season, a strong El Niño is in the cards. But that doesn't guarantee warm and soppy forecasts, Halpert said. Other, more unpredictable climate systems such as the North Atlantic and Artic oscillations, as well as local weather events, can also affect winter storms.

"The climate system is far more complicated than just El Niño, even a strong one," Halpert said.

However, based on the current status, there is about a 60 percent chance for warmer weather than average across the Northern United States, and about a 70 percent chance of wetter weather across the South, he said. Meanwhile, the Rockies, the Great Lakes region, Northern Alaska and Hawaii are expected to face drier-than-average conditions, he said.

California improvement

California is facing its worst drought in hundreds of years, with snowpack at record low levels across much of the state. Nearly half the state faces exceptional drought, with all of the state experiencing some drought, according to the U.S. Drought Monitor.

The El Niño could improve the parched conditions, though exactly how much isn't clear, said Allen Haynes, a hydrologist with the California Nevada River Forecast Center.

The winter forecast does predict wetter weather across Southern California. However, much of the state's water supply comes from snowpack in Northern California, and weather is only weakly correlated to El Niño events there, Haynes said. In addition, the mountains in the north of the state tend to be lower in elevation, so warmer weather could also mean the storms cause heavy rainfall but do not add to the snowpack, the water storage bank for much of the state, Haynes said.

Even if the El Niño brings strong precipitation to Northern California, where it matters most, the soakings are unlikely to erase the four-year deficit in water from the multiyear drought, he said. For instance, the wettest year on record, 1983, brought twice the average yearly precipitation, but completely erasing the current deficit would require between 2.5 and three times the average annual rainfall, he said.

"A full recovery is likely to be uneven across the West and is also likely to take more than one season of above-average precipitation," Haynes said.

In addition, strong rainfalls could bring flooding, especially in areas scarred by forest fires, which lack the natural barriers that absorb water and slow down runoff, Haynes said.

Follow Tia Ghose on Twitter and Google+. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

El Niño is expected to be more beast than "little boy" this year — a forecast about the weather pattern that becomes clear in newly released maps of the waters around the equatorial Pacific Ocean.

The two maps show the sea-surface heights in the Pacific in October 1997 and 2015, revealing that conditions this year are looking a lot like they did during the strong El Niño event of 1997 to 1998. Water expands as temperatures rise, and so sea-surface height is an indicator of warming in the upper layer of the ocean.

"Whether El Niño gets slightly stronger or a little weaker is not statistically significant now. This baby is too big to fail," Bill Patzert, a climatologist at NASA's Jet Propulsion Laboratory in Pasadena, California, told NASA's Earth Observatory.

During an El Niño — which translates as "The Little Boy" in Spanish — an ocean-atmosphere interaction leads to the warming of surface waters in the central and east-central Pacific around the equator. The cyclical phenomenon can affect wind and rainfall patterns worldwide. [How El Niño Causes Wild Weather All Over the Globe (Infographic)]

"Over North America, this winter will definitely not be normal. However, the climatic events of the past decade make 'normal' difficult to define," Patzert told the Earth Observatory.

Measurements of sea-surface heights in the newly released maps came from altimeters onboard the TOPEX/Poseidon satellite (1997) and the Jason-2 satellite (2015). The warmest waters, which are represented by sea-surface heights above normal sea level, can be seen (in red) moving into the eastern tropical Pacific Ocean, while the colder-than-normal — or below-normal sea-surface heights — show up in blue in the western tropical Pacific Ocean.

Experts with the Climate Prediction Center, part of the National Oceanic and Atmospheric Administration, forecast last month that this year's El Niño could be among the strongest on record, dating back to 1950. In August, sea-surface temperatures in the eastern equatorial Pacific Ocean were near or greater than 3.6 degrees Fahrenheit (2 degrees Celsius) above the 1981 to 2010 average, according to the Climate Prediction Center.

The climate pattern is linked with snowy winters in the Northwestern United States and wet winters in the Southwest; drought in Southeast Asia and Australia typically accompany El Niño.

Follow Jeanna Bryner on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

In Costa Rica, El Niño has a strange side effect: More snakebites.

Both the hot and cold phases of the El Niño Southern Oscillation (known as El Niño and La Niña, respectively) are accompanied by an increase in snakebites in the Central American country, according to a new study published today (Sept. 11) in the journal Science Advances. Here's how the climate cycle might be tied to slithering creatures: Snakes are ectothermic, meaning they get their body heat from outside sources. That means their activity is sensitive to climatological factors.

"Snakebites, probably the most neglected of the neglected tropical diseases, [are] another disease showing changes in [the] face of climate change," study researcher Luis Fernando Chaves, a scientist at the Institute of Tropical Medicine at Nagasaki University in Japan, told Live Science. [See Photos of Snakes from Around the World]

Dangerous bites

Snakebites are relatively rare in the United States, but pose a huge problem in many regions, particularly southeast Asia and sub-Saharan Africa. A 2008 study published in the journal PLOS ONE found that at least 421,000 people are bitten by venomous snakes worldwide each year, and some 20,000 die — but those are conservative estimates. Given spotty statistics and reporting, the number of bites could be closer to 1.8 million and related deaths might reach 94,000, the authors reported.

Costa Rica is home to 22 species of venomous snake, according to the Costa Rica Star. The one that most often bites humans is the terciopelo (Bothrops asper), which can be deadly without antivenom treatment. [The World's 6 Deadliest Snakes]

What made Costa Rica useful for studying snakebites, however, was its widely available and free healthcare system. Not only do doctors keep good records of snakebites in the country, Chaves said, people also have access to healthcare after a bite, meaning even the poorest victims get reported.

Chaves and his colleagues studied a database of snakebites that occurred between 2005 and 2013 — 6,424 in total. They found some predictable patterns: There are fewer snakebites at higher elevations, where the climate is cooler. Every degree Celsius increase in average temperature was linked to a 24 percent increase in the number of snakebites. Poorer areas were harder-hit than wealthier areas, in part because poor people in rural areas are often farmers or farm workers, which puts them in direct contact with snakes, Chaves said. Poverty-stricken citizens are also less likely to have well-built homes that keep snakes out, he added.

Snake weather

The crucial finding, however, was an odd increase in snakebites during both El Niño and La Niña. El Niño brings hot, dry weather to Costa Rica; La Niña brings cool moisture.

It's simple enough to explain why hot weather might lead to more snakebites: Snakes are more active when it's warmer, Chaves said. The increase in snakebites linked to the cool weather of La Niña is a little more complicated. The researchers think this increase is linked to El Niño, too, though. Costa Rica has a torrential rainy season, so El Niño's drier weather (which is just less wet) is actually beneficial for plants compared to the usual deluge, Chaves said. More productive plants translate to more prey animals for snakes, which likely lead to a serpentine population eruption.

This is all well and good for the snakes until the El Niño pattern fades, at which point the snakes lose their abundant food supply. The prospect of starvation probably pushes snakes into areas they wouldn't normally go — near humans. This delayed reaction to El Niño's warmth could explain why the number of snakebites goes up again months later, during the cold La Niña. The snakebite count drops again when neither climate pattern is in play, the researchers found.

"This pattern is different from what has been observed for other diseases affected by El Niño," Chaves wrote in an email to Live Science. "For example, in vector-borne diseases (those diseases transmitted by mosquitoes and other bloodsucking insects), only one phase tends to be important."

Snakebites qualify as a neglected tropical disease, according to the World Health Organization, partly because victims tend to be poor and living in rural areas, without access to quality healthcare. In Africa, in particular, the need for antivenom outstrips supply, said study researcher José María Gutiérrez, a scientist at the Clodomiro Picado Institute in Costa Rica, which produces antivenoms for Central America.

Adding to the problem, the manufacturer Sanofi Pasteur recently announced it can no longer afford to produce Fav-Afrique, an antivenom effective against 10 sub-Saharan African snake venoms. Supplies — already short — will run out next year.

The Fav-Afrique shortage won't affect Costa Rica or Latin America, as it's specific to sub-Saharan snakes, Gutiérrez told Live Science. Clodomiro Picado and other manufacturers do make antivenom for Africa, he said, though they don't meet the full need.

"The problem of antivenom availability in Africa is much more complex than the decision of a company to stop production," Gutiérrez said. "It is a multifactorial health problem that demands multifactorial analyses and solutions."

Follow Stephanie Pappas on Twitterand Google+. Follow us @livescience, Facebook& Google+. Original article on Live Science.

In what has become a common refrain this year, yet another month has set a global temperature record, with June 2015 coming in as the warmest June on record going back to 1880. It follows other record or near-record hot months during the first six months of this year, so there’s a good chance 2015 will take 2014’s place atop the podium as the warmest year on record.

The National Oceanic and Atmospheric Administration (NOAA) released temperature data for June on Monday, ranking it as the warmest June in the books. The month was nearly 1.6°F above the 20th century average for June, according to NOAA, and beat the previous hottest June, which happened just last year, by 0.22°F. (NASA data also ranked June as the warmest on record.)

The elevated June temperature was unsurprising, in part because of the robust El Niño going on right now. That cyclical climate event tends to raise the mercury across the globe.

“We can certainly attribute some the record warmth to El Niño, but not all of it, and that amount is not really possible to quantify,” Jessica Blunden, a climate scientist with ERT, Inc., at NOAA, said.

4 Takeaways from the Annual Climate Review Five Graphics That Show 2014’s Record Heat A Broken Record: 2014 Hottest Year

El Niño most directly leads to warmer ocean waters in the tropical Pacific, but that isn’t the only place where seas have been steaming this year. The Northeast Pacific and most of the Indian Ocean have also been hotspots, Blunden said.

Also contributing to June’s heat was the overall warming of the atmosphere thanks to the excess heat trapped by accumulating greenhouse gases. That background heat has tilted the odds toward record global temperatures.

A Climate Central analysis conducted after 2014 became the warmest year on record showed that 13 of the 15 warmest years have occurred since 2000 and that the odds of that happening randomly without the boost of global warming was 1 in 27 million.

Some of those top warm years were when La Niña — the cool counterpart to El Niño — was in place, and were warmer than past El Niño years.

Scientists can’t say for sure what will happening in the remaining six months of 2015, but right now the evidence suggests El Niño will last until spring and will likely strengthen in the coming months, making it a good bet that the globe will see more top warm months.

“We do know that as El Niños strengthen, they do tend to cause global temperatures to rise,” Blunden said. “The first half of 2015 is already 0.16°F warmer than the previous record for the first half of 2010, which happens to be when we had the last El Niño. If this current El Niño does continue to strengthen, it seems almost certain that 2015 will beat out 2014 as the warmest year on record.” 

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Originally published on Climate Central.

Raghu Murtugudde is a professor at the University of Maryland's Earth System Science Interdisciplinary Center (ESSIC) and the Department of Atmospheric and Oceanic Science. Murtugudde contributed this article to Live Science's Expert Voices: Op-Ed & Insights.

We've all seen the headlines: California is struggling with a historic drought that promises to worsen as the summer wears on. Forecasts of an El Niño in 2014 brought hopes of winter precipitation and much needed relief, but El Niño played truant, as it had just two years prior in 2012. With another El Niño predicted this upcoming winter, now is the perfect time to ask: Why have climate scientists' predictions gone wrong? What are we missing? 

The answer most likely lies within the timescale at which we target our forecasts. We can predict the weather to a reasonable degree of accuracy up to ten days in advance, and we can make assumptions about climate on the order of years. But El Niño operates on an intermediate, seasonal scale, and so far it's been difficult to pin down a reliable set of indicators to watch. 

Westerly wind bursts

I participated in a recent study, published in Nature Geoscience, that describes the importance of wind bursts originating in the far western Pacific that blow eastward for weeks at a time during the northern hemisphere fall and winter months. It turns out that these previously neglected winds may be critical for the growth of El Niño. Forecasting these high frequency wind bursts, referred to as westerly wind bursts or WWBs, may be fundamental for increasing the reliability of long-lead El Niño forecasts. In short, they could be the indicators we've been looking for to improve our El Niño forecasts and make "false alarms" a thing of the past.

To understand the importance of WWBs, let's take a step back and look at what we already know about how El Niño works. In normal years, tropical trade winds blow from the east to the west across the Pacific, pushing warm surface waters from South America towards Australia and Asia. As the Earth spins around its axis, the water is also pushed away from the equator due to a phenomenon called the Coriolis effect. (To picture this, imagine the sideward push you feel when riding a merry-go-round). 

As the warm surface water moves westward and poleward, colder waters are brought to the surface in the eastern Pacific, along the coast of South America and near the Galapagos Islands. This process is called upwelling, and forms a "tongue" of cold water that extends westward from South America along the equator. At the same time, the warm surface waters collect more heat from the atmosphere as they move further westward, and form a warm pool near New Guinea, Australia and the Philippines. 

The warm pool heats the air above it, kicking off a cycle that dumps up to five meters of rain each year over the western Pacific. But every few years, the trade winds relax and the warm water held up in the western Pacific sloshes back towards South America, taking the rainfall with it. 

That large-scale inversion of the normal pattern affects global weather and climate, giving rise to droughts and dust storms in Asia, flooding and mudslides throughout the Americas, and other effects that can be felt as far away as Europe and North Africa. The warmest waters hit the South American coast around Christmas. Seeing the anomalous warm waters as an auspiciously timed gift from God, 19th century Spanish settlers named the phenomenon El Niño, or "the Christ Child." 

El Niño is never the same

Over the last several decades, scientists have learned that the warm pool waters do not always slosh all the way back to the South American coast. Sometimes they get stuck around the international date line, but more often than not they will at least reach the Galapagos Islands. Only in extreme cases, such as the El Niño events of 1982 to 1983 and 1997 to 1998, does the warming manage to reach the past the Galapagos to the coasts of North and South America, bringing about the most severe effects. Thus, El Niño has several varieties, or "flavors." 

The date line or warm pool El Niño occurs when the warming is limited to the western Pacific around the date line, and although it has a severe effect on Indian and Indonesian rainfall, the Americas remain largely unaffected.

Canonical or cold tongue El Niño is more common, with the warming covering the region from the date line to the Galapagos and can bring moderate weather perturbations to the Americas and Asia, reaching as far as Africa. 

The extreme El Niño is much more rare and can wreak havoc, causing excess rains and storms in some regions such as the southwestern United States and dust storms and forest fires in Australia and Indonesia. 

WWBs play a crucial role in determining which flavor of El Niño may evolve. They are not exactly weather, since they can last for weeks and occur only two or three times a year. Neither are they a climate phenomenon, since they occur in bursts at subseasonal timescales. They are instead called intraseasonal variabilities, and are typically random and hard to predict. They push the eastern edge of the warm pool further eastward at a speed of fewer than 10 kilometers per day. 

But when the WWBs are strong and extend eastward of the date line, they can set off eastward propagating waves that travel along the equator at speeds of more than 250 kilometers per day, reaching the Americas in about three months. These waves push the cold waters down around the Galapagos and along the coasts of the Americas, creating warm surface waters that further weaken the trade winds and create a powerful feedback loop. The El Niño can grow quickly in such cases, producing a severe event like the devastation that emerged in the summer and fall of 1997.

Forecasting El Niño

While WWBs are hard to predict initially, they do have a strong and predictable growth pattern once they manage to push the warm pool eastward past the date line. The greatest hope for improving El Niño forecasting now depends on extending the range of weather forecasting from a few days to several weeks in order to capture the onset of WWBs. The 2014 El Niño forecast failed largely because climate scientists did not predict that the WWBs would be unable to push the warm pool past the date line.

We now wait eagerly to see if the WWBs will begin to push the warm pool past the date line. If they do, it is highly likely the WWBs will bring about either a cold tongue El Niño or an extreme El Niño as we experienced in 1997. 

The parched state of California would do well with an extreme El Niño. The U.S. National Oceanic and Atmospheric Administration (NOAA) has recognized that forecasts on the order of two to four weeks are a high priority, and has already initiated experimental forecasting at those timescales. 

A crucial next step is to integrate this longer-term weather forecasting with existing El Niño forecasting within NOAA, in order to deliver much needed long-lead El Niño forecasts with greater skill and reliability.

Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google+. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.

Severe floods in Texas and Oklahoma are causing devastation after multiple storm systems battered a formerly drought-stricken area, according to experts.

Heavy rainfalls began on Saturday (May 23) and soaked the region through the weekend, leading to nearly record-breaking rains in some southern areas of Texas and Oklahoma. Flash flooding and tornadoes have also been reported in certain cities and towns. At least 10 people have been reported dead across Oklahoma and Texas, and thousands have been evacuated from their homes and are seeking temporary shelter.

These catastrophic conditions are being caused by an El Niño pattern — a natural climate cycle that brings warmer-than-average temperatures to the Pacific Ocean — that has split the jet stream into two branches, with one river of air going off north and the other one sinking farther to the south, said John Gresiak, a senior forecaster for AccuWeather. It is the southern stream that is causing the disturbances in Texas and Oklahoma, after passing through California and Mexico, he added. [Fishy Rain to Fire Whirlwinds: The World's Weirdest Weather]

"Just looking at San Antonio, as of this date they've had double their rainfall for May, and they'll probably get more," Gresiak told Live Science.

The area has been experiencing severe drought for about five years, so residents are no longer used to the large amounts of rainfall that typically fall at this time of year, said Walt Zaleski, the warning coordination meteorologist for the regional headquarters of the National Weather Service (NWS) in Fort Worth, Texas.

"It's not out of the ordinary for us to be getting severe storms that produce thunderstorms and hail," he told Live Science.

While this "drought-buster" rainfall is a welcome relief to cities that had been facing lower-than-usual reserves, the amount of rain that has come all at once has been difficult for residents to deal with, he said. In just four months, the water has replenished lakes that were previously 20 to 25 feet (6 to 8 meters) below normal levels.

Flash flooding, which occurs suddenly when an intense amount of rain falls over a short period of time, has also been an issue. In Wimberley, Texas — a town just southwest of Austin — the Blanco River rose to 40 feet (12 m) from 9 feet (2.7 m) in just 2.5 hours, Zaleski said.

There won't be a reprieve yet from the water, as severe storms are expected to remain in the forecast. For the next couple of days, however, meteorologists at the NWS are expecting the worst of the storms to hit west of Texas, where fewer people live. Regions that are farther east may get battered again with severe weather toward the end of the week, Gresiak said.

Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

Expect another bountiful crop of blue jellies this year along West Coast beaches.

Billions of "by-the-wind sailors," also called Velella velella, could wash ashore in coming months because of favorable water temperatures and onshore winds, scientists say. People have already spotted thousands of the baseball-size creatures at beaches from Washington to Southern California. A gargantuan number of the stunning sea sailors were also blown onto western beaches in 2014.

Velella are outfitted with a stiff, chitinous sail that catches the breeze like a ship does. Because the sail angles against the eastern Pacific's prevailing northwesterly wind, the little blue sailors usually tack offshore. Clusters of them are commonly seen drifting at sea. But when the winds shift to the southwest, as in late winter and spring, the masses may be blown onshore to rot and die.

While some Velella always wash up on West Coast beaches each spring, the unusually large numbers seen in recent months may be connected to warm water off North America, said Dave Checkley, a professor at the Scripps Institution of Oceanography and director of the California Cooperative Oceanic Fisheries Investigations program. [Album: Amazing Photos of Jellyfish Swarms]

A huge blob of warm water has been parked off the West Coast for months, and a budding El Niño is also spiking ocean temperatures off California. The Velella clusters could be following these warm currents, or perhaps a by-the-wind sailor baby boom is in effect. With a life cycle of less than a year, the Velella must quickly reproduce to take advantage of plentiful food.

"When warm water invades our part of the world, Velella commonly comes with it," Checkley told Live Science. "It's really quite fascinating, so I say enjoy it. They're part of nature and they're beautiful."

Velella float on the ocean surface, drifting with the winds. Though the creatures are not true jellyfish, they fill a similar role in the ocean and are also in the phylum Cnidaria, as are jellyfish, coral and sea anemones. A Velella's electric-blue body hangs down into the water, with stinging tentacles that capture small prey such as tiny shrimp and plankton. The blue color provides protection from the sun's ultraviolet radiation, Checkley said.

In the ocean, floating snails, sea slugs and sunfish will gobble up the gelatinous creatures for meals.

Although Velella toxins are harmless to humans, it's not a good idea to handle the jelly creatures and then touch your eyes or mouth. The Velella neurotoxin might cause itching.

Checkley said beachgoers shouldn't miss this opportunity for a close look at an unusual sea creature. "Put them in some water and see how the tentacles hang," he said. "Try to figure out who might they eat and what might eat them. They're not going to hurt you."

Follow Becky Oskin @beckyoskin. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

The West can expect its warm and dry weather to continue through the summer, while the central Plains will be relatively cool and wet, according to a summer forecast released today (May 21).

The East will be slightly warmer than average, and drought will intensify in the Northeast and the Pacific Northwest, a pattern that's typical of El Niño summers, the National Oceanic and Atmospheric Administration said.

Texas and Oklahoma have already felt the force of El Niño-influenced weather, NOAA said in a briefing today. Both states were in a severe drought last year, but this spring, drenching rainstorms refilled the states' parched reservoirs to near capacity. Kentucky also saw a soaking spring, recording its second wettest April on record. "This pattern is partially the effect of El Niño conditions," said David Unger, a forecaster with NOAA's Climate Prediction Center.

The Texas drought began in October 2010 and was the second-driest spell in the state's history, said Victor Murphy, a program manager for the National Weather Service's Southern Region. "It looks like the Texas drought is pretty much over," Murphy said. [The 5 Worst Droughts in US History]

In summer, a strong El Niño often steers heavy rainstorms toward the southern Plains states and the intermountain West, including Texas, Oklahoma, Colorado, Arizona and New Mexico. However, the summer forecast calls for dry conditions in the West and Alaska, Unger said.

An El Niño also tends to tamp down Atlantic hurricane activity and boost Pacific hurricanes; NOAA plans to release its hurricane forecast on May 27.

The El Niño is a cyclic climate phenomenon that involves both the ocean and the atmosphere. One of its hallmarks is warmer-than-average sea-surface temperatures in the tropical Pacific Ocean. Although the El Niño fizzled last winter, the pool of warm water stuck around this spring and strengthened into a full-blown event.

With an El Niño brewing in the Pacific, the warm tropical ocean surface has been helping set new global heat records this year. Global temperatures in April 2015 were the fourth warmest on record since 1880, said Jake Crouch, a NOAA climatologist. And the first four months of 2015 shattered old heat records.

During January through April, the average temperature across land and ocean surfaces was 1.44 degrees Fahrenheit (0.8 degrees Celsius) above the 20th-century average. This surpassed the previous record, set in 2010, by 0.13 F (0.07 C).

"2015 is very warm compared to other years," Crouch said. "It has been really quite a bit ahead of the pack."

Follow Becky Oskin @beckyoskin. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

The first three months of 2015 set new global heat records, government officials announced today (April 17).

January, February and March set new high-temperature records, respectively; each month was warmer than any on the books since record keeping started 136 years ago. March also ended the hottest 12-month period on record, the National Oceanic and Atmospheric Administration (NOAA) reported. Seven of the past 11 months have tied or set new record-high monthly temperatures.

In March, Earth's average temperature was 56.4 degrees Fahrenheit (13.6 degrees Celsius), breaking the previous record set in 2010 by 0.09 F (0.05 C). The Japan Meteorological Agency also put March in first place, as the hottest month ever in its records, while NASA put it in third place, behind 2010 and 2002. Yet, all three agencies agree that the 12 months to date are the hottest ever. [Fishy Rain to Fire Whirlwinds: The World's Weirdest Weather]

Giant blobs of warm water in the tropical and northeast Pacific Ocean helped boost 2015 to the top of the rankings, according to the NOAA climate report. Like a pot of boiling water on a stove, the warm seawater radiates heat into the atmosphere and raises the planet's average temperature. The global average temperature includes measurements over land and ocean surfaces.

Because these warm-water pools are predicted to persist through year-end, more heat records could fall in the coming months. In the tropical Pacific, the warm water is linked to an ongoing El Niño, the cyclic phenomenon that shifts global weather. NOAA forecasts a 60 percent chance that the El Niño will last through fall.

March 2015's new record high was a bigger jump from the global average than records set during previous El Niño years, in February 1998 and January 2007, NOAA reported. The average March temperature over land surfaces across the globe was 2.86 F (1.59 C) above the 20th-century average.

During March, California saw record warmth, as did parts of the western United States and Canada, according to the report. Scandinavia, northwest Russia, south central China, northeast Australia and eastern Africa also baked under high temperatures, NOAA reported.

The only place on Earth with notably cooler-than-average temperatures in March was northeastern Canada. Despite the record-breaking snow and chilly temperatures along the Atlantic Coast earlier this year, no state set a new cold record in the first three months of 2015, according to NOAA.

Follow Becky Oskin @beckyoskin. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

A blob of warm water in the Pacific Ocean may be to blame for some of the bizarre weather in the United States this year, a new study suggests.

From the dry spell in the West to the East Coast's endless snow season, the country has seen its share of weird weather so far in 2015. For that, scientists say, you can thank (or curse) a long, skinny blob in the Pacific Ocean about 1,000 miles (1,600 kilometers) off the West Coast, stretching all the way from Mexico to Alaska.

"In the fall of 2013 and early 2014, we started to notice a big, almost-circular mass of water that just didn't cool off as much as it usually did. So by spring of 2014, it was warmer than we had ever seen it for that time of year," study co-author Nick Bond, a climate scientist at the University of Washington, said in a statement.

This warm blob, which is about 2 to 7 degrees Fahrenheit (1 to 4 degrees Celsius) warmer than the usual temperature for this region, means the winter air that crosses over the Pacific Ocean wasn't cooled as much as it normally would be. That, in turn, spelled warmer, dryer conditions for the West Coast. [Fishy Rain to Fire Whirlwinds: The World's Weirdest Weather]

The blob

Scientists first observed the patch of warm water in June 2014, when Bond noticed that Washington state had experienced a milder winter than usual. At that point, the warm patch stretched about 1,000 miles (1,600 km) in each direction and was 300 feet (91 meters) deep.

Since then, the warm blob has persisted, though it has become a long, skinny finger of water instead. In a study published Monday (April 6) in the journal Geophysical Research Letters, Bond and his colleagues argue that a high-pressure ridge above the Pacific Ocean over the past two winters had led to calmer seas. Without roiling waters to transfer heat to the cold air above it, the ocean remained warmer than usual, the team concluded.

People can also thank the blob (in part) for the drought conditions experienced in California, Oregon and Washington this year. As the air cycles over the warmer water, it heats up and brings less snow, translating into drier conditions inland.

What's more, this warm blob has been disrupting ocean ecosystems, the researchers said. For instance, fish have been spotted in new waters, in part because they lack the normally nutrient-rich, cold waters that upwell from deep in the ocean. Skinny and dying sea lion pups and seabirds have been washing ashore off California's coast, according to the "Annual State of the California Current Ecosystem Report."   

Larger pattern

East Coasters can blame wonky ocean temperatures off the Pacific for all those weeks spent shoveling snow, according to another study published March 19 in the journal Geophysical Research Letters. A decadal pattern called the North Pacific Mode, a pattern of higher-than-average sea-surface temperatures that snakes from the tropical Pacific to the waters off coastal California to the northern Pacific, caused the weird weather. The pattern sent rivers of cold, wet air into the Midwestern and East Coast states, while forcing hot dry air across the American West, the study found.

"Lately, this mode seems to have emerged as second to the El Niño Southern Oscillation in terms of driving the long-term variability, especially over North America," said study author Dennis Hartmann.

This same climate variability helped create the warm blob, and has been getting progressively more influential on global weather patterns since 1980, the study found.

Follow Tia Ghose on Twitterand Google+. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

This year's El Niño may not only bring a bit of drought relief to parched Western states, but also could deliver a quiet tornado season, a new study finds.

Much of the southeastern United States faces a lower risk of tornadoes during El Niño years, the new research shows. The effects are strongest in Oklahoma, Arkansas and northern Texas. Damaging hail is also less likely during a strong El Niño, researchers report today (March 16) in the journal Nature Geoscience.

"The cool thing is, you can actually forecast what the spring tornado season will be like," said lead study author John Allen, a severe weather climatologist at Columbia University's International Research Institute for Climate and Society in Palisades, New York. [The Top 5 Deadliest Tornado Years in U.S. History]

The team's experimental forecast for this March, April and June calls for a slightly lower risk of tornadoes due to this year's El Niño. There is a 60 percent chance of an average tornado year, a 30 percent chance of a below-normal year and a 10 percent chance of an above-average number of tornadoes, the researchers said. However, even a quiet year can see deadly twisters strike in the United States, Allen said. In 2013, a relatively quiet tornado year, a late May tornado outbreak killed dozens in central Oklahoma.

Tornado forecasts

Allen and his colleagues are part of a group of scientists who intend to start issuing seasonal tornado forecasts that are similar to the hurricane and seasonal outlooks issued by the National Oceanic and Atmospheric Administration (NOAA). The experts have been meeting yearly since 2012 to advance the science of forecasting tornadoes.

Currently, the National Weather Service's Storm Prediction Center issues tornado outlooks up to eight days in advance. In contrast, hurricane outlooks come several months ahead of the summer storm season.

However, though the Columbia University research team plans to issue its own forecast as soon as next year, optimistically, an official forecast is at least five years away, said Ashton Simpson Cook, a meteorologist at the Storm Prediction Center who was not involved in the research. "We've already started on it, [but] we're in the beginning phase," he told Live Science.

The new findings are based on a comparison of weather records during El Niño years versus La Niña years. The authors did not use historical tornado records, which are fraught with reporting biases. Instead, they analyzed the environmental conditions that favor severe weather, such as temperature, atmospheric moisture and wind shear, which is different wind directions and speeds at different elevations above the surface. Then, the team created a forecasting formula that linked wintertime El Niño-La Niña conditions to the probability of severe storm activity in the following months.

"This is a great study," Cook said. "It's the next step in assessing the role of ENSO [El Niño] on severe weather, not just tornadoes."

Warm ocean, few tornadoes

The El Niño-La Niña cycle, or ENSO, is a natural climate pattern in the Pacific Ocean. During an El Niño, warm sea surface temperatures spread across the tropics. In a La Niña year, the opposite happens: Cool sea surface temperatures dominate in the eastern tropical Pacific. These temperature shifts have a ripple effect on wind patterns around the world, which, in turn, affects where storms form. [Fishy Rain to Fire Whirlwinds: The World's Weirdest Weather]

NOAA declared El Niño’s arrival last week, after Pacific Ocean sea surface temperatures crossed a warm threshold and wind patterns shifted in response.

So far, the 2015 tornado season is off to a slow start, with 28 tornados reported, according to the Storm Prediction Center. However, Allen said the cold weather across the eastern United States likely had a stronger effect than El Niño conditions on suppressing tornadoes so far this winter.

In an El Niño year, the jet stream is more southerly, which tamps down the wind patterns that generate severe storms. (For instance, the southerly flow brings cool, dry air from the plains and Canada.) The weather patterns that form twisters and hail decreased by 25 to 50 percent during an El Niño, the study reported.

During a La Niña year, the jet stream across North America shifts to the North, which favors more tornadoes in the Southeast. This brings warm, moist air into Tornado Alley, the twister-prone regions of the United States. Tornado and hail activity doubled across Oklahoma, Arkansas and northern Texas during strong La Niña years, the researchers reported. The opposite pattern is seen in the Gulf Coast and Florida panhandle, with an increase in tornado activity during El Niño and a drop during La Niña years, the researchers also noted.

"There is a geographical dependence, which explains why it might be hard to untangle the impact if you were to just look at the total number of tornadoes [each year] in the U.S.," said study co-author Michael Tippett, a climate scientist at Columbia University.

Direct observations from earlier studies agree with the findings. For example, there were spikes in tornado activity during strong La Niña years, such as in 1999 and 2011. Strong El Niño years brought a drop in tornados, in 1969 and 1988.

Follow Becky Oskin @beckyoskin. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

Just when everyone had pretty much written it off, the El Niño event that has been nearly a year in the offing finally emerged in February and could last through the spring and summer, the National Oceanic and Atmospheric Administration announced Thursday.

This isn’t the blockbuster, 1998 repeat El Niño many anticipated when the first hints of an impending event emerged about a year ago. This El Niño has just crept across the official threshold, so it won’t be a strong event.

“We’re basically declaring El Niño,” NOAA forecaster Michelle L’Heureux said. “It’s unfortunate we can’t declare a weak El Niño.”

In part because of its weakness, as well as its unusual timing, the El Niño isn’t expected to have much impact on U.S. weather patterns, nor bring much relief for drought-stricken California.

But forecasters say it could nudge weather patterns in other areas of the globe, especially if it persists or intensifies, and could boost global temperatures — following a 2014 that was already the hottest year on record.

“It does tilt the odds toward warmth,” L’Heureux said.

The Difference a Year Makes

Forecasters with NOAA’s Climate Prediction Center and the International Research Institute for Climate and Society (IRI) at Columbia University first raised the alert early last year that an El Niño might be taking shape. They based it on a subsurface plume of warm water, called a Kelvin wave, surging from west to east across the tropical Pacific. (It was this large plume that drew comparisons to the monster El Niño of 1998, which caused deluges and flooding in many parts of the world and significantly amped up global temperatures. 1998 is still the only 20th century year among the top 10 warmest.)

Why Do We Care So Much About El Niño? Global Warming May Worsen Effects of El Niño, La Niña Events A Broken Record: 2014 Hottest Year

An El Niño is marked by unusually warm waters over the central and eastern parts of this basin. The CPC officially considers it an event when the sea surface temperatures in a key region of the ocean reach at least 0.5°C, or about 1°F, warmer than average.

Multiple Kelvin waves have pulsed across the ocean basin in recent months and ocean temperatures have repeatedly been warm enough in that region to qualify as an El Niño.

But ocean temperatures alone don’t define an El Niño; CPC forecasters also look for the corresponding shifts in atmospheric patterns, namely a weakening of the typical east-to-west trade winds over the region. Those altered winds can affect weather around the globe. That’s why they are watched so carefully month after month.

A year after that first sign of an impending El Niño surged across the ocean, another Kelvin wave is making its way across the basin. Only this time, the ocean is already much warmer and most importantly, the atmosphere seems to have finally gotten the memo, with the trade winds weakening.

The coupling between ocean and atmosphere isn’t following the usual script, and the typical shifts in rain patterns haven’t emerged. But L’Heureux noted the rarity of any response from the atmosphere at this time of year. In spring, she said, it is harder for the ocean and atmosphere “to essentially see each other.”

“We’re fairly amazed,” she said.

Spring and Summer

This late winter emergence of the El Niño means that the hallmark U.S. impacts — wet and cool conditions across the southern U.S. — won’t happen.

“Over us [the impact] becomes very, very muted” in spring, L’Heureux said.

Forecasters believe the current Kelvin wave and the already warmer ocean temperatures, signal that the El Niño is going to persist, which was another factor in officially declaring an event.

The CPC forecasts a 50 to 60 percent chance that the El Niño will chug along through the spring and summer. If it does, it could tamp down the Atlantic hurricane season and juice the season in the eastern Pacific, as many said it did last summer, before the El Niño was official.

That official designation has already spurred much debate in the climate community, since the ocean was warm enough through much of 2014 to qualify as an El Niño.

“I’m sure it’s going to be discussed quite a bit,” L’Heureux said. [View graphic of 27 years of above-average temperatures]

But whether or not those warm oceans meant an El Niño was in place, they, along with warm waters in other ocean basins, helped elevate global surface temperatures in 2014, leading to the warmest year on record.

Whether that could happen again in 2015 remains to be seen, though the ocean has a strong temperature memory and doesn’t respond to changes very quickly. So that warmth is likely to hang on, or even rise.

“If the El Niño intensifies, it may have a greater impact on the global temperatures, as observed from past events,” Jessica Blunden, a climate scientist with ERT, Inc., at the NOAA’s National Climatic Data Center, said in an email. “But for now we are in a wait and see mode.”

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Scientists can determine a lot about past climates by taking core samples from trees that have lived for hundreds or thousands of years. The study of a tree’s rings is called dendrochronology. 

The width of tree rings indicates the climate while the tree was growing. One ring represents one year. Thinner rings represent years when growth was stunted by lack of water.

The extremely strong La Niña events that can shake up global weather patterns may soon hit nearly twice as often as they did previously, due to global warming, researchers say in a new study.

The researchers analyzed global climate models that can simulate extreme La Niña events. Results showed that extreme La Niña events may soon strike about every 13 years, as opposed to about every 23 years, as they do now.

The findings do not suggest a regular schedule of extreme La Niña events every 13 years, said lead study author Wenju Cai, a climate scientist at the Commonwealth Scientific and Industrial Research Organization in Aspendale, Australia. "We're only saying that on average, we expect to get one every 13 years," Cai explained. "We cannot predict exactly when they will happen, but we suggest that on average, we are going to get more."

La Nina events can trigger floods, heat waves, blizzards and hurricanes worldwide, researchers said. The new findings also suggest that some areas could get whiplashed with weather of opposite extremes from year to year — for example, droughts one year and floods the next, the scientists added.

La Niña, which is Spanish for "little girl," involves unusually cool waters in a belt 5,000 miles (8,000 kilometers) long across the equatorial Pacific Ocean. It is the counterpart of El Niño, which is Spanish for "little boy" and involves unusually warm waters in the same area. South American fisherman named El Nino for the baby Jesus, after noticing that the ocean would heat up around Christmastime. [Weirdo Weather: 7 Rare Weather Events]

Both El Niño and La Niña can alter wind and water currents across the globe, causing extreme weather that can kill thousands of people and result in billions of dollars in damage.

"During the 1998-1999 La Niña event, the southwestern United States experienced one of the most severe droughts in history," Cai said. In Venezuela at that time, flooding and landslides killed 25,000 to 50,000 people, and in China, floods and storms killed thousands and displaced over 200 million people. In Bangladesh, where over 50 percent of the country's land area flooded, food shortages and waterborne diseases killed several thousand people and affected over 30 million. During that La Niña, Hurricane Mitch, one of the deadliest and strongest hurricanes on record, killed more than 11,000 people in Honduras and Nicaragua, Cai said.

In 2014, Cai and his colleagues predicted that as the globe warms due to increased levels of greenhouse gases in the atmosphere, extreme El Niño events may hit about every 10 years, instead of about every 20 years as they do now. Since El Niño is essentially the opposite of La Niña, "one would have thought if extreme El Niño is increasing in frequency, perhaps the frequency of extreme La Niña might decrease," Cai said. But they found the opposite.

The scientists also found about 75 percent of extreme La Niña events will occur immediately after an extreme El Niño event.

"The implications are profound," Cai told Live Science. "It means affected regions will experience opposite extremes from one year to the next."

The researchers noted their finding is counterintuitive, since it predicts that global warming can lead to more intense cold-water related activity such as extreme La Niña events. However, Cai explained that a region of Southeast Asia between the Indian and Pacific Oceans known as the Maritime Continent, which includes Indonesia, Philippines and Papua New Guinea, will warm faster than the central Pacific Ocean in a warmer world. This difference in temperature can drive unusually strong easterly winds that drive warm water westward and pole-ward, which in turn brings colder water from the deep ocean closer to the surface.

Cai explained why extreme La Niña events will usually occur immediately after an extreme El Niño event: During an extreme El Niño event, heat from the upper layers of ocean water gets released into the atmosphere, driving circulation in the atmosphere and ocean that can ultimately enhance Pacific cooling.

"Our results call for measures to reduce greenhouse gas emissions so as to reduce such risks," Cai said.

The scientists detailed their findings online today (Jan. 26) in the journal Nature Climate Change.

Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

Wintry storms could bury Buffalo, New York, under heaps of snow until Christmas, but 2014 will still be the hottest year on Earth since 1880, climate scientists said today (Nov. 20).

"It's becoming pretty clear that 2014 will end up the warmest year on record," said Deke Arndt, chief of the climate monitoring branch at the National Climate Data Center. "The remaining question is, by how much." 

The eastern United States was one of Earth's cold zones this year, with temperatures running 2.7 degrees Fahrenheit (1.5 degrees Celsius) below average, scientists from the National Oceanic and Atmospheric Administration (NOAA) said today during the agency's monthly climate briefing. But the bitter cold couldn't offset record-breaking heat waves in California, Europe and Australia this year, nor the incredible warmth in the world's oceans. [In Images: Extreme Weather Around the World]

"Notably, every major ocean basin and every continent all had some pieces — and some had significant pieces of their area — that were the warmest on record [during 2014]," Arndt said. "It's virtually certain that California will have its warmest year on record, even if California has record cold in December."

October was the sixth straight month of chart-busting heat in the oceans, according to NOAA. Last month was also the hottest October on record for land temperatures.

Combining land and sea temperatures, the average worldwide temperature of 58.43 F (14.74 C) for October 2014 topped the previous high set in October 2003 by 0.02 F (0.01 C). November 2013 through November 2014 is now the warmest 12-month stretch on record for any 12-month period recorded since 1880, NOAA said.

With less than two months left in 2014, the planet is on track to beat the warmest years in the historical record. So far this year, worldwide temperatures are averaging 58.62 F (14.78 C). The entire planet would have to go through a cold snap for 2014 to miss finishing in the top 10. (And it may feel that way for people in eastern North America and eastern Russia, where heavy snows arrived early this year.)

Two giant pools of warmer-than-average water in the Pacific Ocean helped boost global temperatures in 2014, NOAA scientists said. One pool is sloshing around the eastern Pacific along the equator, and is related to the El Niño climate pattern that is struggling to develop. The other pool is a large mass of warm water stretching from Alaska to California. These warm, West Coast waters suggest that a decades-long natural climate pattern called the Pacific Decadal Oscillation (PDC) has flipped into its positive phase, said NOAA forecaster David Unger. The PDO influences weather in North America by shifting the jet stream and changing where rain and snow fall, similar to El Niño's worldwide effects.

Sea surface temperatures in the northern Pacific Ocean haven't been this warm in 10 years, Unger said. "Whether it will stay this way, only time will tell," he said. The PDO has generally been in a negative, or cold phase, since 1998, scientists think.

Follow Becky Oskin @beckyoskin. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

El Niño conditions continue to sputter in the tropical Pacific Ocean, pushing back the odds of even a weak El Niño emerging this winter, forecasters said today (Nov. 6).

The National Climate Prediction Center now puts the chances of an El Niño at 58 percent, a sharp drop from the 80 percent chance forecasted in June.

An El Niño forms when the warmest surface water in the equatorial Pacific drifts eastward, toward South America. The strong early forecast from the Climate Prediction Center (CPC) and other climate modelers came about thanks to an enormous blob of hotter-than-average water spotted in the central and eastern Pacific this spring. [Fishy Rain to Fire Whirlwinds: The World's Weirdest Weather]

However, it takes more than warm ocean temperatures to declare an El Niño. Weather experts also want to see the ocean and atmosphere lock in to the new regime, with more westerly low-level winds and an eastward shift in cloudiness and rainfall.

There have been a few bursts of westerly winds since June, but overall, the expected atmospheric pattern failed to take hold, like a car engine that revs but won't start. As a result, the likelihood of an El Niño has dropped month by month.

"Right now, only the ocean is passing the test," said Anthony Barnston, chief forecaster at Columbia University's International Research Institute for Climate and Society in New York. "The average sea surface temperatures are high enough to pass as a weak El Niño, but the atmospheric indicators are like neutral years."

Because El Niño events usually peak in December, there's not much time left for the atmosphere to fire up its winds and storms. "It's now or never," Barnston told Live Science. "The season is just about over."

If an El Niño does materialize in the next few weeks, it could last until March or April. Otherwise, if the phenomenon fails to appear, the pool of warm, tropical water will persist, making ocean conditions favorable for another try next summer. "The storehouse of heat sets the stage for a good possibility of an El Niño for the following year," Barnston said.

El Niño events typically occur every three to five years but can cycle over as much as two to seven years. Researchers aren't sure what triggers El Niño, a natural climate cycle that fiddles with storms, rainfall and drought worldwide.

Follow Becky Oskin @beckyoskin. Follow LiveScience @livescience, Facebook & Google+. Originally published on Live Science.

Fueled by the steady rise of greenhouse gases, 2014 is on track to go down as the hottest year on record.

With September 2014 in the books as the warmest September on record and the year-to-date temperatures tying with 1998 and 2010 as the warmest January-September, the National Climatic Data Center announced Monday that 2014 will likely break the record for the warmest year on the books.

Back in August, the year ranked as the third warmest on record. The jump this month came “because we keep seeing record warm months or near-record warm months,” said Jessica Blunden, a climate scientist with ERT, Inc., at the NCDC.

In fact, leaving aside calendar years, the period from October 2013 through September 2014 “is the warmest 12-month period that we’ve ever had on record,” Blunden told Climate Central.

All but one of the 10 warmest years on record have occurred in the 21st century (1998, when there was a very strong El Niño, is the exception). Earth’s steadily rising temperatures are the result of the buildup of greenhouse gases, such as carbon dioxide, in the planet’s atmosphere. These gases cause the atmosphere to warm, and a large chunk of that warmth is absorbed by the world’s oceans.

Those oceans, particularly the northeastern and equatorial Pacific, are largely what is fueling this record, Blunden said. Because temperatures in the oceans are slow to change, it is likely that warmth will hang around through the end of the year. That means that the odds “are pretty good” that 2014 will top 2010 as the warmest year on record, she said.

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September for the globe as a whole was 1.3°F above the 20th century average of 59°F, according to the NCDC, which is part of the National Oceanic and Atmospheric Administration. The period from January-September was 1.22°F above the average of 57.5°F for the 20th century.

Those numbers and rankings broadly agree with records kept by NASA and the Japan Meteorological Agency, both of which also ranked September as the warmest on record. Different agencies use different methods of compiling global temperatures, accounting for slight variations in their numbers and rankings from month-to-month and year-to-year.

At the beginning of the year, NCDC climate scientists weren’t sure how the year would turn out. The end of 2013 saw an uptick in global warmth, with a particularly toasty November and December and they expected that trend to continue into 2014, as it largely did. (2013 ended up ranking as the fourth warmest on record.)

“You never know for sure what’s going to happen in a climate system based on natural variations,” Blunden said.

While the winter was a brutally cold one for the eastern half of the U.S., and spring seemed to be more of an extension of winter there, much of the rest of the globe was experiencing anomalous warmth. In some places, including the Northeast Pacific, that warmth reached record-setting levels.

“We’re just having these incredible ocean temperatures,” Blunden said. Ocean temperatures in September broke the record for the warmest of any month, she said.

With the ocean warmth expected to continue and an El Niño event trying to form, that makes it likely that the final three months of the year will also be among the warmest. That would stand in contrast to 1998 and 2010, where the record warmth started to taper off at the end of both years, in part because El Niños that were in place at the beginning of those years died down.

The land area of the planet is perhaps the biggest unknown in the coming months because they change temperature more rapidly, but if the El Niño forms, that will stack the deck because during an El Niño “you tend to have more warmth over land areas in general,” Blunden said.

The NCDC has worked out that if each of the remaining months of this year at least matches the average of its 10 warmest occurrences, then 2014 will be the warmest year on record. If each month ties its average so far this century, then the year will tie 2010 as the warmest.

The October 2013 to September 2014 period broke the 12-month record, besting the one tied just one month before, from September 2013 to August. 2014. (The other two years in that second-place tie were August 2009 to July 2010 and September 1997 to August 1998.)

With October more than halfway over, it is possible this month will also set a temperature record, and could break the 12-month record yet again. “So we just have to see how that plays out,” Blunden said.

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Like August before it, September 2014 was the warmest September on record, according to newly updated NASA data. The warm month makes it even more likely that 2014 will become the warmest year on record.

This September was about 1.4°F above the 1951-1980 average temperature for the month, data from NASA’s Goddard Institute for Space Studies (GISS) showed. That makes it the warmest September in GISS records, edging out the previous September record set in 2005. GISS records extend back to 1880.

September followed what both NASA and the National Climatic Data Center (NCDC) rated as the warmest August on record, and what NASA ranked as the fourth warmest summer on record globally. NCDC’s temperature data for September will be released later this week.

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When August’s record-breaking warmth was announced, Jake Crouch, an NCDC climatologist, said, “if we continue a consistent departure from average for the rest of 2014, we will edge out 2010 as the warmest year on record.” For that to happen, each of the remaining months of the year would only have to rank among the top five warmest, he added.

With the NASA data suggesting September easily met that mark, it becomes more likely that 2014 will take the top slot.

Ocean temperatures have played a large role in 2014’s warmth, including the warmer-than-normal sea surface temperatures in the tropical Pacific Ocean that have accompanied an emerging El Niño, Kevin Trenberth, a climatologist with the National Center for Atmospheric Research, told Climate Central in an email.

The ocean is where some 90 percent of the excess heat trapped by greenhouse gases is stored.

Of the five warmest years on record (2010, 2005, 1998, 2013, and 2003, in that order), only 2013 and 2014 didn’t start with a mature El Niño, according to the National Oceanic and Atmospheric Administration, the parent organization of the NCDC.

The El Niño is still being given a two-thirds chance of forming before the year is out, which bolsters the likelihood that 2014 will become the warmest year in the books.

Gavin Schmidt, the NASA GISS director, has cautioned against trying to find larger-scale meaning in the exact records of specific months, as the difference between first and second place can be very small and natural variability plays a large role from month-to-month and year-to-year.

Instead, he told Climate Central last month, the important trend to watch is the overall long-term picture of warming, which the recent “run of warm months” feeds into.

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That El Niño we’ve been tracking for months on end — the one that is taking its sweet time to form — still hasn’t emerged, forecasters announced Thursday.

But the reason we still care so much about it, following all of its tiny fluctuations toward becoming a full-blown El Niño, is that it can have important effects on the world’s weather, including in the U.S. It can even boost global temperatures, helping set the planet on the course to be the warmest year on record.

In their monthly update, scientists at the National Oceanic and Atmospheric Administration’s Climate Prediction Center and the International Research Institute for Climate and Society at Columbia University said there is still a two-thirds chance that a weak El Niño event emerges and that it will likely do so in the October-to-December timeframe, lasting until spring 2015.

“I think it’s pretty safe to say that we’re essentially taking one step forward, that is one month forward since last month,” CPC forecaster Michelle L’Heureux told Climate Central.

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While the conditions that mark an El Niño — such as warmer-than-average sea surface temperatures in the tropical Pacific and a reversal of prevailing winds in the region — haven’t fully gotten in synch, they still can, and in some cases are, impacting the global climate and weather.

There’s a robust connection between El Niños and quiet Atlantic hurricane seasons, which the 2014 season has turned out to be, and hurricane experts have said that the burgeoning El Niño is part of the reason.

Even though waters in the eastern and central parts of the tropical Pacific haven’t consistently been warm enough to herald an El Niño, they are still affecting the atmosphere in a way that creates more stable, subsiding air over the Atlantic and more wind shear. Both of those factors tamp down on hurricane formation and development.

“This is fairly typical in fall” when the system is leaning toward El Niño conditions, L’Heureux said.

Those warmer waters, particularly ones in the central tropical Pacific, also helped bump this past summer into the books as the warmest summer on record. That heat has put 2014 on the path to possibly becoming the warmest year on record. If the El Niño continues to develop and forms before the end of the year, it will help nudge the planet toward that record.

The story isn’t quite the same for other El Niño impacts, namely the connection to a wet winter in Southern California. Only strong El Niños are associated with above-average winter precipitation there, something the region desperately needs in the midst of a three-year drought that is one of the most intense in the state’s history. But with this El Niño expected to be a weak one, the picture for California’s winter is unclear right now.

“We can’t rule anything out,” L’Heureux said.

Other areas also see their precipitation affected by an El Niño, particularly in the Northern Hemisphere winter, with Indonesia and northeastern South America tending toward drier-than-normal conditions, for example. Places like Southeast Asia and northwestern North America tend to see warmer-than-normal temperatures. Those impacts can in turn affect agriculture, by bringing too much or too little rainfall to crops, as well as public health, by, for example, reinforcing the conditions in which mosquitoes that spread malaria breed.

Just as the exact impacts depend on how strong an El Niño is, they can also depend on its timing, both when it fully forms and when it peaks.

The expected start time for this El Niño is on the later end of the typical timescales for such events to emerge, but not unprecedented.

“There is a very wide range of start times,” L’Heureux said. “Anywhere from April to the end of the year.”

If the El Niño arose in the late fall, but then began to decay quickly, in January or February, then some of the typical impacts seen in the U.S. would be affected because they don’t typically emerge until the January-to-March timeframe.

“We do need the El Niño forcing to persist,” L’Heureux said.

L’Heureux and her fellow forecasters expect this El Niño to persist into the spring, but nothing is certain when it comes to El Niño. The record of at least fairly reliable sea surface temperature records extends back only to 1950. With such a relatively short record, El Niño researchers don’t think they have seen all the varieties of El Niño that can form, both in terms of onset and strength.

“We haven’t observed all that we can observe,” L’Heureux said. “So it’s not just what we know, but what don’t we know about El Niño evolution.”

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Ocean currents that deliver important nutrients to shallow, coastal waters have become weaker and more variable over the last half-century, which could affect fish and other marine animals that nourish themselves in these nutrient-rich waters, according to a new study.

Data records spanning almost 600 years have shown that the strength of coastal upwelling off the west coast of North America has become more variable since 1950. Researchers pieced together this long-term look at ocean trends from an unlikely source: tree rings.                         

Coastal upwelling happens when winter winds lift deep, nutrient-rich waters up to the shallow layers of the sea. These nutrients fuel phytoplankton growth in the sunlit surface waters. Since 1950, California has experienced more winters with weak coastal upwelling than in the last five centuries. Researchers found that years with weak upwelling were associated with slower growth in fish populations and lower reproduction rates for seabirds, the researchers said. [In Photos: The Wonders of the Deep Sea]

But the weather pattern that causes the coastal upwelling also blocks storms from coming ashore. This causes drought and stunts the growth of trees. Blue oak trees along the California coast are particularly sensitive to winter precipitation, Bryan Black, assistant professor of marine science at the University of Texas at Austin, told Live Science.

Trees grow a new ring every year. By looking at a cross-section cut through the bark of a tree, scientists can count up the rings and determine a tree's age. Differences in the ring sizes reveal good seasons and bad seasons, with a thick ring signaling that the tree had a good growing season. The researchers found an inverse relationship between tree growth and the well-being of the marine ecosystem, Black explained.

"The winters we see robust growth in the trees, we see poor growth in the marine ecosystem," Black said.

Coastal upwelling happens during the winter when a strong, high-pressure weather system develops along the west coast of the continent. The system spins clockwise and brings in winds from the north. That spin combines with the rotation of the Earth to move the waters off shore and stir up clouds of nutrients. Phytoplankton at the surface rely on this seasonal influx of nutrients. These organisms are the backbone of the marine ecosystem and support huge populations of fish and seabirds.

Some variation in coastal upwelling from year to year is normal, but most direct data records don't go back more than 70 years. This makes it difficult for marine scientists to spot any long-term trends. By studying tree-ring patterns, however, researchers can piece together a much longer record of how coastal upwelling has changed.

To determine how upwelling influenced marine life, the researchers used data on yearly fish population growth since the 1940s, along with data on seabird egg laying and the survival of baby seabirds since the 1970s. By comparing the tree-ring data to the fish and seabird statistics, the researchers found that years with weak upwelling and lots of tree growth correlated with years when fish and seabird populations suffered.

Based on tree ring measurements taken by David Stahle, a tree ring expert and professor of geoscience at the University of Arkansas in Fayetteville, the team found that four out of the 10 weakest upwelling years in the past 600 years occurred after 1950. Seven out of 10 weakest years have happened since 1850.

While the data show there are years in which bird and fish populations don't fare well, "it's not necessarily indicative of a long-term decline," Black said, since the bird and fish populations usually bounce back within a couple years after a bad season.

Black said it's unclear if climate change is causing the recent high variation in coastal upwelling.

"California climate can be very extreme," Black said. "The 20th century is particularly variable in the context of the last few centuries, but it's not necessarily unique to history."

The upwelling does appear to be linked to the weather pattern El Niño, and climate records have shown El Niño to be unusually variable over the past century. Black said the area has certainly entered a highly variable time, but even a 600-year data record doesn't come close to capturing the whole picture. The recent variation could be part of a larger cycle that scientists can look back far enough to see.

The researchers hope to use climate models to predict future variability in coastal upwelling. Details of the study were published online today (Sept. 18) in the journal Science.

Follow Kelly Dickerson on Twitter. Follow us @livescience, Facebook & Google+. Original article on Live Science.

For months now, the tropical Pacific Ocean has been flirting with blossoming into a full-fledged El Niño state: Waters off the coast of South America have warmed, a hallmark of the climate phenomenon, but then cooled, only to warm once again. Winds, which normally blow east-to-west have made tentative moves in the other direction, another key criteria, but the bottom line is that the whole El Niño package hasn’t come together.

So, is this El Niño going to happen or not?

“Most likely” is the answer from forecasters with the National Oceanic and Atmospheric Administration’s Climate Prediction Center and the International Research Institute for Climate and Society at Columbia University, who issue monthly forecasts.

Whether or not the El Niño forms, when it does so and how strong it is has a bearing on theweather and climate impacts it can have around the world. It is thought that even the neutral-but-tending-toward-El Niño conditions in place right now are helping to tamp down Atlantic hurricane activity, but only strong El Niños are linked to enhanced rains in Southern California, which the state desperately needs.

How Will We Know When El Niño Finally Arrives?  El Niño Expected to Limit 2014 Hurricane Season  Why Do We Care So Much About El Niño?

The latest update, issued Thursday, notes that some aspects of the tropical Pacific’s behavior look more promising than they did at the time of the last update in early August, but keeps the likelihood of an El Niño developing at 60 to 65 percent.

“We still believe that the event will occur,” CPC forecaster Michelle L’Heureux told Climate Central.

When might this happen?

Sometime in the September to November time frame, the CPC forecast said. Once the El Niño does form, it is expected to continue into the early part of 2015. The event, though, is only expected to be a weak or moderate one, L’Heureux said.

El Niño is the warm phase of the larger phenomenon called the El Niño-Southern Oscillation. During an El Niño, the waters in the eastern part of the tropical Pacific are warmer than usual and the trade winds that normally blow from east to west weaken or even reverse. (During its counterpart, La Niña, the eastern waters are cooler and the normal trade winds are intensified.)

The temperature threshold that forecasters use to mark an El Niño is a warming of 0.5°C (0.9°F) — the sea surface temperatures in a particular area of the tropical Pacific must have met this condition for a month and be expected to do so for the next three months.

Temperatures have hit that mark, but then were not expected to persist, and over the summer, they even cooled somewhat.

Things seem to be back on track now, with temperature differences hanging around the 0.5°C mark. This is also where most models have been hovering in recent runs, just eking past the El Niño threshold.

“It’s actually been a little unnerving” to look at the models, L’Heureux said. (In 2012, forecasters called for an El Niño to form, but it eventually fizzled out. So far this year, the models haven’t dropped the development of the phenomenon like they did then.)

The recent warmer waters came after a burst of westerly winds touched off what is known as a Kelvin wave, when warmer waters travel below the surface of the water from west to east. What exactly its full impact will be won’t be known until later this month or into October, though.

El Niño watchers “have to be patient and see what happens,” L’Heureux said.

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The El Niño that seems to be trying to form in the tropical Pacific Ocean is looking a little less likely now, though the chances of it developing are still double the normal odds, forecasters said in the latest monthly update on the cyclical climate phenomenon, released Thursday.

That update lowered the odds of an El Niño occurring in fall and early winter to 65 percent, down from 80 percent last month. But “we’re still fairly confident that El Niño will come,” said Michelle L’Heureux a meteorologist with the National Oceanic and Atmospheric Administration’s Climate Prediction Center, who puts out the El Niño forecasts along with the International Research Institute for Climate and Society at Columbia University.

If and when the El Niño forms, it would influence weather and climate patterns in particular regions around the globe, for example, tamping down on hurricane activity in the Atlantic Ocean. Depending on its strength, it could also drive up global temperatures enough on top of the rise from human-induced warming to send 2015 into the record books.

How Will We Know When El Niño Finally Arrives?  El Niño Expected to Limit 2014 Hurricane Season  Why Do We Care So Much About El Niño?

While above-normal sea surface temperatures in the far eastern tropical Pacific — a hallmark of an El Niño event — have persisted, the warmth in other key surface regions and below the surface has ebbed. The shifts in atmospheric patterns that accompany an El Niño also have yet to materialize. These factors combined caused forecasters to lower the odds.

The updated probabilities mean that instead of a 4-in-5 chance that an El Niño would materialize, there is now a 2-in-3 chance it would, L’Heureux said.

But even a 65 percent chance is double the typical odds of seeing an El Niño in winter, she said.

Forecasters think any El Niño that does develop will be a weak to moderate in strength, though a strong event can’t be completely ruled out. But going from such a current weak showing to a strong El Niño “would certainly be unprecedented,” L’Heureux told Climate Central.

El Niño is the warm phase of a larger cycle called the El Niño-Southern Oscillation, which includes its counterpart La Niña. Normally, the western tropical Pacific is warmer than the east, but during an El Niño, this pattern reverses. The trade winds that normally blow from east to west weaken or even reverse.

L’Heureux and other forecasters have been watching the development of this potential El Niño since issuing an El Niño Watch in March. In April, the situation looked ripe for an El Niño to form this summer, as a huge plume of warm water, called a Kelvin wave, slid through the ocean and brought exceptionally warm waters to the eastern Pacific. The development drew comparisons to the strong El Niño of 1997-1998.

But while the ocean looked set for the El Niño, the atmosphere wasn’t playing along, and storm activity developing over Indonesia, which normally dries during an El Niño.

Over the past month, the pool of warm water below the ocean’s surface (and at an area of the ocean surface called the Niño 3.4 region) has dissipated, prompting L’Heureux and her colleagues to say ENSO is still in its neutral phase.

The cool-down in the Niño 3.4 region was actually anticipated by the ENSO forecast models, and is consistent with the upwelling phase of the Kelvin wave, when some of the excess heat dissipates. The fact that they caught that slight dip gives L’Heureux and her colleagues more confidence that the models are on target in their continued projections that an El Niño will actually develop.

“To me, that enhances their credibility,” L’Heureux said.

And while she is loathe to compare any one El Niño to another since the record of well-observed El Niños is short, L’Heureux said that other El Niños saw similar dips in sea surface temperatures around this time in the season before finally forming. Of the seven El Niños that have formed since 1990 (as far back as weekly sea surface temperature records go), three — 1994, 2004 and 2006 — saw similar drops, all of which happened in late June and July.

“So there is precedent for this, I guess, sort of summertime lull,” L’Heureux said. And summer is actually a tricky time to get the atmosphere and ocean to act in sync, she added, so it could simply be seasonal effects keeping the El Niño from moving forward.

While forecasters are still betting an El Niño will happen, L’Heureux did say she keeps looking back at the data from 2012, when what forecasters thought would be an El Niño completely fizzled. They called off that watch when the sea surface temperatures were near average across the whole tropical Pacific and the models were “starting to tank,” she said. “And we really haven’t reached that point” with this event, she added.

The models suggest that some of the lost heat will come back, but if the atmosphere doesn’t start playing along and the heat doesn’t regenerate, “the models will catch on,” L’Heureux said.

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Huge wildfires sparked by a powerful El Niño event 16 years ago left a distinct tinge of sulfur in Antarctica's snow, a new study reports.

This is the first time researchers have detected a climate signal from El Niño-driven wildfires in Antarctica's snow. The discovery raises hopes that the signal, which is linked to a unique sulfur molecule, could be detected in older ice as well — and perhaps shed light on the chemistry of Earth's ancient rocks.

"We hope we would be able to go back and understand past El Niño events before anthropogenic [human] influences," said lead study author Robina Shaheen, a geochemist at the University of California, San Diego (UCSD). "The same chemistry was happening in the Precambrian [period] as well." [50 Amazing Facts About Antarctica]

Isotopes are versions of the same elements, such as sulfur, with different numbers of neutrons in their nuclei, giving them different mass. Four nonradioactive, or stable, isotopes of sulfur occur naturally on Earth. Researchers use sulfur isotopes to peer into the planet's conditions in the deep past, such as during the Precambrian period, before complex life arose on Earth.

When snow falls in Antarctica, it carries trace amounts of isotopes that are circulating in Earth's atmosphere. Because the snow doesn't melt completely each year, the layers are like time capsules of Earth's atmosphere. Eventually, this snow becomes ice, trapping and preserving more than a million years of atmospheric chemistry, researchers think.

Shaheen and her co-authors analyzed sulfur isotopes in snow that fell between 1984 and 2001 in Antarctica, looking at variations between the seasons. Their findings were published today (Aug. 4) in the journal Proceedings of the National Academy of Sciences.

The team saw spikes in sulfur levels caused by volcanic eruptions, which inject sulfate particles high into the atmosphere. The sulfate circles the Earth, and eventually some snows down on Antarctica.

But a strange pattern of sulfur anomalies also turned up in snow from 1997 to 1998, a season with no volcanic eruptions big enough to blast sulfur all the way to Antarctica.

"1998 is the biggest isotopic signal of them all," said study co-author Mark Thiemens, an isotope geochemist at UCSD. "It was a real surprise and totally unexpected."

The ratio of sulfur isotopes also changed dramatically in 1998, providing clues to the source of the unusual shift.

The researchers think the sulfur ratio changed because of raging wildfires caused by El Niño-triggered drought. The wildfires likely sent sulfur sky-high on huge pyrocumulonimbus clouds, the researchers said.

"The wildfires were so large that they shot a lot of sulfur into the stratosphere," Thiemens told Live Science. The stratosphere is the layer of Earth's atmosphere above the troposphere, which is the atmosphere humans live in and breathe.

According to their model, the source of the big sulfur shift could be a molecule called carbonyl sulfide. Burning plants emit both sulfate and carbonyl sulfide. In the stratosphere, ultraviolet (UV) light breaks down carbonyl sulfide into sulfur dioxide.

The unusual sulfur isotope pattern linked with carbonyl sulfide also turned out to be strikingly similar to rocks deposited before plants ever existed — in Earth's deep past, 2.4 billion years ago. This era marks a sudden jump in oxygen levels, which geochemists can detect in ancient rocks.

"The same photochemistry [caused by UV light] may have been happening in the Precambrian period," Thiemens said. The reaction could account for some of the sulfur deposited in rocks around the time that oxygen levels started to rise. Accurately counting those sulfur levels is important because they affect estimates of how much oxygen was present in Earth's atmosphere 2.4 billion years ago.

Shaheen added, "Carbonyl sulfide [has been] totally ignored in models of when oxygen started to increase on the planet."

Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on Live Science.

Every month since March, when the first El Niño Watch was issued, forecasters, government officials around the world, and yes, even those in the media, have been watching with bated breath to see whether various climate agencies would officially pronounce the arrival of that infamous climate phenomenon. So far, no clear-cut El Niño has been declared, but that hasn’t stopped the continual updates and dissections of the most recent seasonal forecasts and trends in ocean temperatures and winds, as if they were the latest juicy plot twist on “Scandal” or “Game of Thrones.”

If you aren’t among those obsessively tracking Kelvin waves and the Nino3.4 region — and the next “official” update is expected on Aug. 7 — you may wonder what all the fuss is about. After all, El Niño is just the warming of ocean watersin the tropical Pacific. So why the heck do we care so much about it?

We care because this seemingly isolated event is just one part of the global climate system and can actually have major influences on the weather and climate around the world, from the U.S. to Australia to eastern Africa. For example, El Niño shifts atmospheric patterns in a way that typically brings more rain to the southern U.S., but drought to Indonesia. Those changes can, in turn, have economic and health consequences, such as altering the crop yields in agricultural markets or providing a more conducive environment for the spread of malaria. Because of these impacts, groups at the U.S. National Centers for Environmental Prediction, or NCEP (which is part of the National Oceanic and Atmospheric Administration), the Australian Bureau of Meteorology, and other organizations around the world watch the changing conditions in the Pacific Ocean and make forecasts for whether and when an El Niño might develop.

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El Niño also leads to warmer average global temperatures, which come atop the underlying trend of rising temperatures spurred by global warming. The only year in the top 10 warmest globally that wasn’t during the 21st century was 1998, when one of the strongest El Niños on record was in force.

Not all of El Niño’s effects are negative: The atmospheric changes it spurs tend to tamp down on tropical cyclones and hurricanes in the Atlantic Ocean basin, something denizens of the Caribbean and Gulf and East coasts of the U.S. surely appreciate.

“In an El Niño year, you have winners and losers,” Walter Baethgen, a senior research scientist with the International Research Institute for Climate and Society at Columbia University’s Earth Institute, said in an IRI video.

Exactly what impacts are seen and when they emerge can depend on the timing of an El Niño — the current event is expected to emerge late this summer or early in the fall. But even while one is building, it can still influence weather conditions, as this event seems to be doing. The strength that a full-blown El Niño achieves can also affect the impacts it brings — for example, the excess rains that parched California so desperately needs seem only to be a feature of a strong El Niño.

“There is a lot of variety in exactly how strong they get, exactly what month they begin, or are identified as El Niño events, as well as the exact month in which they peak,” said IRI director Lisa Goddard during a press call held by the climate communication group Climate Nexus. “So all of these differences can influence (El Niño’s) regional climate impacts.”

What Is El Niño?

El Niño is a cyclical climate phenomenon that occurs every 3 to 5 years (though that return period can be as short as 2 and as long as 7 years). It’s defining characteristic is the buildup of warmer-than-normal surface waters over the eastern and central tropical Pacific Ocean. (This warm phase is part of a larger cycle called the El Niño-Southern Oscillation that also has a neutral phase and a cold phase, called La Niña.)

These warmer waters are linked to — or coupled with, as atmospheric scientists say — changes in the trade winds over the region. In neutral conditions, these winds blow from east to west across the basin, piling up the warm water in the western portion of the basin, near Indonesia. But during El Niño, the winds relax, and the warm water slides back east, like a ball rolling down a hill.

The warm water fuels thunderstorms in the atmosphere overhead, which in turn warms the atmosphere through a process called latent heating. The shift in where the warm water is and the increase in the heat the ocean releases cause a shift in this storminess and heating, which affects one of the main circulations of the atmosphere, the Hadley circulation. The Hadley circulation features air rising near the equator and traveling toward higher latitudes where it sinks and flows back to the equator. The increased heat from El Niño turbocharges the poleward flow, which in turn causes further changes in atmospheric flow, including to the jet stream over the Pacific.

“The phenomenon itself is specific to the tropical Pacific, even though it does have worldwide impacts,” Goddard said during the press call.

While the atmospheric conditions with the current anticipated event haven’t yet shaped up to the point that NCEP and IRI forecasters are willing to officially declare an El Niño, they still place an 80 percent chance on one happening by late fall.

“It’s fairly confident, but it’s not a slam dunk,” Anthony Barnston, IRI’s chief forecaster, told Climate Central.

Teleconnections

Not every place in the world is affected by El Niño, and not every El Niño produces the same effects as previous ones. But “there are places that have fairly reliable” climate effects, orteleconnections, Barnston said.

The most robust effects are precipitation-related. Both Indonesia and northern South America typically see below-normal rains that can lead to drought, while more rain is typically seen over southeastern South America, eastern equatorial Africa and the southern U.S.

The above-average rainfall in the southern U.S. is linked to the changes in the jet stream, as it tends to funnel more storms over the region.

There is interestingly one tiny area of northern South America, along the coasts of Ecuador and Peru, that actually sees increased rainfall. The rains are driven by the warmer waters just off the coast as they fuel storm activity. Such rains were actually seen earlier this spring when a particularly warm blob of water worked its way over to the eastern Pacific and fueled storms.

Not all of the changes linked to El Niño always occur: El Niño is linked to a less active monsoon over India, leading to drought conditions there, but this effect was missing during the 1997-1998 El Niño, one of the strongest on record. (The monsoon has been lackluster so far this year, but it’s unclear whether or not that’s related to the burgeoning El Niño, Barnston said.)

“So there is an expectation of certain ENSO impacts, but there’s not a guarantee, and so that’s where seasonal forecasts become very important,” he said.

El Niño can also lead to temperature changes, with the northern tier of the U.S. tending to be warmer than normal and the southern tier cooler. The latter effect is related to the increased precipitation, which tends to moderate temperatures, while the former is linked to the stronger jet stream (and is the more robust of the two connections). The more intense flow tends to fence off cold Arctic air, keeping incursions like last winter’s Polar Vortex episodesfrom impacting the northern parts of the country.

The temperature effects of El Niño go beyond trends in particular regions. The heat released from the oceans bumps up the planet’s average temperature, in addition to the warming caused by the heat trapped by accumulating greenhouse gases in the Earth’s atmosphere. (The tendency toward cooler conditions in the Pacific over the past couple of decades could be the main driver of the slowdown in the rate of warming over the same time period, as such conditions cause the ocean to store more of that building heat.)

“The state of the tropical Pacific can really affect global temperatures just through the fact that you’re getting all this ocean heat either absorbed or released,” Gerald Meehl, a senior scientist with the National Center for Atmospheric Research in Boulder, Colo., said during the same press call as Goddard.

Even a moderate El Niño, like the one that arose in 2010, can raise global temperatures — 2010 was, in fact, the warmest year on record. If the current El Niño is commensurate with the 2010 one, global temperatures will likely top those in 2010 because they will add a similar amount of heat on top of the already warmer background created by global warming, Goddard said.

All in the timing

The biggest impact to global temperatures tends to come about two to four months after an El Niño peaks, which typically happens during the Northern Hemisphere winter. (An El Niño event usually peters out by March of the year after it develops.) That background seasonal climate helps determine what the impacts of the El Niño are.

“The seasonality -- what the weather and the climate is typically at that time of year -- is important to how ENSO impacts it,” Goddard said. So knowing when El Niño will kick in is key to anticipating economic and societal impacts.

In general, most of the impacts of El Niño come during its winter peak, particularly for the U.S. That’s because the Pacific jet stream is weaker in the summer, so any changes to it make less of a difference than for the stronger winter jet stream, said NCEP forecaster Michelle L’Heureux.

Californians are hoping that the El Niño will bring enhanced winter rains, to make up for the disappointing rainy seasons of the past 3 years, which has left the entire state in high levels of drought. But the El Niño rains in Southern California are best correlated with strong El Niños. Right now it is not expected that this one will be strong, but even a moderate El Niño could mean that the area sees something closer to a normal rainy season, Barnston said.

Some places do see their biggest impacts outside of the Northern Hemisphere winter: Dryness that can affect Africa’s Sahel and damage agriculture there tends to occur from July to September (meaning the area could avoid much of this impact if the El Niño doesn’t fully develop soon).

In general, the Southern Hemisphere tends to see more year-round effects than the Northern Hemisphere, L’Heureux said, because El Niño peaks during their summer, though their strongest effects also come during their winter.

The impacts in Southern Hemisphere locales like Australia and Indonesia are also more instantaneous than those in the U.S. because of their proximity to the region where El Niño originates. They also see stronger, more robust impacts.

The drier conditions typically seen in both of those spots can increase the odds of damaging wildfires, which come along with economic costs, as well as impacting crop yields. If, for example, drought reduces the Australian wheat crop, that can affect the availability of wheat in food markets as well as food prices, Baethgen said in the IRI video (though wheat from areas that see more rain could offset this). Countries like the U.S. are more resilient in the face of such effects than places like Mozambique, whose agriculture is sensitive to El Niño’s Southern Hemisphere summer effects, Barnston said. Forecasting can help such vulnerable societies prepare for these impacts.

Places that see more rain could see negative as well as positive impacts. A little rain can be helpful in places like southeastern South America, but too much can expose crops to disease. Excessive rains can also have health impacts: In Kenya during the 1998 El Niño, rains caused catastrophic flooding that seriously damaged health infrastructure and spread malaria and Rift Valley fever.

Those impacts are why forecasters like Barnston, Goddard, and L’Heureux are working to better predict El Niños and understand the climate impacts they have. It is also why places like the IRI and the World Meteorological Organization are working to disseminate what we do know about El Niño and improve communication and coordination between meteorologists and government agencies and officials who would need to prepare for potential impacts.

“There have been major improvements in the understanding of El Niño, its climate effects and associated impacts over the past several decades within and, importantly, outside the scientific community,” said Maxx Dilley, director of the WMO’s Climate Prediction and Adaptation Branch.

An IRI study conducted earlier this year and found, for example, that agricultural interests are increasingly using El Niño forecasts to prepare for future seasons.

There’s still a lot of work to do to be able to predict El Niños further out and understand why some effects only show up sometimes, but if forecasters could take what they know and create better awareness of and preparedness for the impacts that are known, “the El Niño years have a potential to be the least costly to society,” Goddard said.

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California just finished the hottest first half year on record, a period going back 120 years, according to the national climate overview for June released by the National Oceanic and Atmospheric Administration (NOAA).

The statewide average temperature for the period was 58°F, or 4.8°F above the 20th century average. That bests the previous warmest January-June in 1934 by 1.1°F — a substantial difference, said Jake Crouch, a climate scientist with NOAA’s National Climatic Data Center.

The record exemplifies a temperature pattern that has held across the country for much of the year, with above-average temperatures in the West and below average in the East. The pattern has kept monthly average temperatures for the entire U.S. -- as well as the average temperature for the year-to-date -- in the middle of the pack record-wise, but has contributed to the stunning drought that has propagated across California.

And though temperatures across the U.S. as a whole haven’t set any records this year, the global average has been a different story. The year through May was the fifth warmest on record, according to NOAA data, which ranked May as the warmest on record, as did NASA and the Japan Meteorological Agency (JMA). Preliminary NASA data suggests that June 2014 will come in as the third warmest June on record, while the JMA ranks it as the warmest in their temperature records. (Different agencies process temperature data using slightly different methods, but the differences between rankings are very small.)

NOAA expects its global data for June, which will be released on July 21, to be “in the same ballpark” as the NASA and JMA rankings, Jessica Blunden, a climate scientist with ERT, Inc., and a NOAA contractor who helps write the monthly reports, said in an email.

Could 2014 Become the Warmest Year on Record?  A Cold U.S. Winter for Sure, but 8th Warmest Globally  Graphic: U.S. Summer Temperature Trends

With an El Niño expected to develop late this summer or in the fall, there is a chance that 2014 could move into the spot as the warmest year on record, though the climate phenomenon’s effects are generally most pronounced in the colder months, so the boost it gives to global temperatures could be reserved for 2015.

The colder temperatures that made the eastern U.S. stand out as one of the very few blue spots on global temperature maps for much of the year have abated as summer has taken hold. Above-average temperatures were the story for June along the East Coast and in the Midwest and Southwest. The Gulf Coast and Central Plains saw near-average temperatures, while only the Northern Rockies and Northern Plains saw below-average temperatures.

Though no state saw a top 10 warmest or coldest June, Arizona and California came close, with June 2014 ranking the 11th warmest for both states. The month was the 33rd warmest June for the U.S. as a whole, with average temperature 1.1°F above the 20th century average of 68.5°F. It was minimum, or nighttime, temperatures that were particularly warm for June, hitting an average of 1.7°F above the 20th century average of 55.7°F.

Warming nighttime temperatures are a concern with global warming, as they lessen the evening relief places rely on during heat waves.

All six months of 2014 so far in California have ranked in the top 10 percent of warmest, according to NOAA. This heat, along with a rainy season that failed to live up to its name, has put all of the state in at least severe drought conditions, with nearly 80 percent in the extreme or exceptional drought, the two highest categories recognized by the U.S. Drought Monitor.

Temperatures in California are up again in mid-July, as a high-pressure ridge sits over the West and brings in dry conditions, the counterpart to a trough that has dipped down and brought cooler weather to the East once again.

The dryness out West is in stark contrast to the rains that fell elsewhere and made June the sixth wettest on record. Most of those rains fell across the Midwest and Central and Northern Plains, bringing with them serious floods. The rains fell in part because the jet stream struggled to migrate northward as it usually does at this time of year, allowing low-pressure systems to wash across the U.S., in place of the high-pressure ridges that typically settle in and send temperatures rising.

Dry places are expected to get drier with climate change, while wet places are expected to get wetter, but Crouch said that the particular precipitation pattern seen in June isn’t what is expected in a warming world, according to theNational Climate Assessment that was released in May.

“These contradictory points make the connection between the most recent precipitation extremes and climate change hard to make,” Crouch told Climate Central.

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California's rainfall year ended today (June 30), and though the totals are not yet official, the parched state will likely end up with one of its lowest rainfall years since the 1920s.

California's precipitation year runs from July 1 through June 30, to account for the fact that most of California's rain and snow falls in the winter months. (Confusingly, there's also a separate "water year," which runs from Oct. 1 to May 31.) When the rain meter ticked over last night, the most recent total was 49 percent of the historical average, according to the state's Department of Water Resources. Rainfall totals have been tracked since the 1850s.

The entire state has been under drought conditions since Jan. 2013, and many of its water reservoirs are lower than normal because of two preceding dry years. [Photos: The 10 Driest Places on Earth]

This year's dry spell can be partly linked to a stubborn high-pressure system sitting off California's shores, nicknamed the "ridiculously resilient ridge." This high-pressure ridge acted like a roadblock for winter storms that typically deliver California's rain and snow. The high pressure steered east-flowing storms north, toward the Pacific Northwest, instead of allowing tropical moisture to crash into California's mountains.

The same high-pressure ridge has also sent temperatures soaring, with California sweating through its hottest year on record. January through May 2014 was the hottest string of months in that state since 1895, according to the National Climatic Data Center.

This year is the third consecutive below-normal water year for California. California Gov. Jerry Brown declared a drought emergency for the state on Jan. 17. The entire state is in severe drought conditions, with 77 percent in an extreme drought and 33 percent considered to be in an exceptional drought, according to the National Drought Mitigation Center.

Many communities have ordered water-use restrictions, and farmers are feeling the effects of low water allocations from the state.

The city of Bakersfield, in California's farm-rich Central Valley, received 2.41 inches (6.12 centimeters) of rain, or 37 percent of normal precipitation through June 29, according to the National Weather Service. The same region received 3.15 inches (8 cm) from July 1, 2012, through June 29, 2013, which is 49 percent of normal for the water year.

Here are some of the precipitation totals, as of June 29, from the National Weather Service.

• Los Angeles: 6.08 inches (15.44 cm); 41 percent of average
• Sacramento: 10.35 in (26.29 cm); 51 percent of average
• San Francisco: 12.54 in (31.85 cm); 53 percent of average
• San Diego: 5.06 in (12.85 cm); 49 percent of average
• Fresno: 4.81 in (12.22 cm); 42 percent of average

While an El Niño offers hope of a wet year in Southern California, a moderate or weak event could mean another dry winter in 2014.

Forecasters say there is an 80 percent chance of an El Niño developing by fall, but it's no slam-dunk. This Pacific Ocean climate phenomenon shifts global weather patterns, and often means heavier-than-normal winter rainfall in Southern California. But most of California's winter rainfall occurs in Northern California's Sacramento and San Joaquin river basins, and an El Niño may not bring enough winter rain for the thirsty state to recover from the ongoing drought, water experts say.

In the Sacramento Valley — the state’s largest source of water supply — there’s a 29 percent chance that the 2014-2015 rainfall year will also be critically dry, and a 64 percent chance that it will be a combination of dry or critically dry, according to researchers at the University of California, Davis, Center for Watershed Sciences. Water years are divided into five types, ranging from critically dry to wet.

"Given the odds, it makes sense to prepare for another dry year," the researchers wrote on the center's California Water Blog.

Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on Live Science.

This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.

We wait in anticipation of droughts and floods when El Niño and La Niña are forecast but what are these climatic events?

The simplest way to understand El Niño and La Niña is through the sloshing around of warm water in the ocean.

The top layer of the tropical Pacific Ocean (about the first 200 metres) is warm, with water temperatures between 20C and 30C. Underneath, the ocean is colder and far more static. Between these two water masses there is a sharp temperature change known as the thermocline.

Winds over the tropical Pacific, known as the trade winds, blow from east to west piling the warm top layer water against the east coast of Australia and Indonesia. Indeed, the sea level near Australia can be one metre higher than at South America.

Warm water and converging winds near Australia contribute to convection, and hence rainfall for eastern Australia.

In a La Niña event, the trade winds strengthen bringing more warm water to Australia and increasing our rainfall totals.

In an El Niño the trade winds weaken, so some of the warm water flows back toward the east towards the Americas. The relocating warm water takes some of the rainfall with it which is why on average Australia will have a dry year.

In the Americas El Niño means increased rainfall, but it reduces the abundance of marine life. Typically the water in the eastern Pacific is cool but high in nutrients that flow up from the deep ocean. The warm waters that return with El Niño smother this upwelling.

Have El Niño and La Niña always been around?

El Niño and La Niña are a natural climate cycle. Records of El Niño and La Niña go back millions of years with evidence found in ice cores, deep sea cores, coral and tree rings.

El Niño events were first recognised by Peruvian fisherman in the 19th century who noticed that warm water would sometimes arrive off the coast of South America around Christmas time.

Because of the timing they called this phenomenon El Niño, meaning “boy child”, after Jesus. La Niña, being the opposite, is the “girl child”.

Predicting El Niño and La Niña

Being able to predict an El Niño event is a multi-million, possibly billion dollar question.

Reliably predicting an impending drought would allow for primary industries to take drought protective action and Australia to prepare for increased risk of dry, hot conditions and associated bushfires.

Unfortunately each autumn we hit a “predictability barrier” which hinders our ability to predict if an El Niño might occur.

In autumn the Pacific Ocean can sit in a state ready for an El Niño to occur, but there is no guarantee it will kick it off that year, or even the next.

Nearly all El Niños are followed by a La Niña though, so we can have much more confidence in understanding the occurrence of these wet events.

A variety of events

Predictability would be even easier if all El Niños and La Niñas were the same, but of course they are not.

Not only are the events different in the way they manifest in the ocean, but they also differ in the way they affect rainfall over Australia – and it’s not straightforward.

The exceptionally strong El Niños of 1997 and 1982 have now been termed Super El Niños. In these events the trade winds weaken dramatically with the warm surface water heading right back over to South America.

Recently a new type of El Niño has been recognised and is becoming more frequent.

This new type of El Niño is often called an “El Niño Modoki” – Modoki being Japanese for “similar, but different”.

In these events the warm water that is usually piled up near Australia heads eastward but only makes it as far as the central Pacific. El Niño Modoki occurred in 2002, 2004 and 2009.

Australian rainfall is affected by all its surrounding oceans. El Niño in the Pacific is only one factor.

As a general rule though, the average rainfall in eastern and southern Australia will be lower in an El Niño year and higher in a La Niña. The regions that will experience these changes and the strength are harder to pinpoint.

El Niño and climate change

It is not yet clear how climate change will affect El Niño and La Niña. The events may get stronger, they may get weaker or they may change their behaviour in different ways.

Some research is suggesting that Super El Niños might become more frequent with climate change, while others are hypothesising that the recent increase in El Niño Modoki is due to climate change effects already having an impact.

Because climate change in general may decrease rainfall over southern Australia and increase potential evaporation (due to higher temperatures) then it would be reasonable to expect that the drought induced by El Niño events will be exacerbated by climate change.

Given that we are locked into at least a few degrees of warming over the coming century, it’s hard not to fear more drought and bushfires for Australia.

Jaci Brown does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

This article was originally published on The Conversation. Read the original article. Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google +. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.

Last month was the warmest May ever measured on Earth in 134 years, the National Oceanic and Atmospheric Administration (NOAA) announced today (June 23).

The record warmth comes from a combination of global warming and a natural climate pattern in the Pacific Ocean called El Niño, scientists think.

Several regions around the world suffered record heat in May, while a few were colder than average, but NOAA looks at the planet's overall temperature to gauge global trends. The average combined land and ocean surface temperatures in May were 1.33 degrees Fahrenheit (0.74 degrees Celsius) higher than the 20th-century average of 58.6 F (14.8 C), NOAA said in a statement. The last time May temperatures dipped below the 58.6 F average was in 1976, according to NOAA. The last below-average month was in 1985.

May's toasty temperatures were boosted by record-setting surface heat in the tropical Pacific Ocean, NOAA said. The global sea surface temperatures during May jumped 1.06 F (0.59 C) above the 61.3 F (16.3 C) average, also a new May record. [Video: Watch 60 Years of Rising Temperatures]

This Pacific Ocean warmth is a feature of the vast El Niño climate event developing in this region. During an El Niño year, typical Pacific weather patterns reverse, with bathlike warm water replacing cold currents in the eastern equatorial Pacific Ocean.

This huge swath of warm water strongly points to an El Niño, a periodic climate swing that can shift global weather patterns, such as rainfall and drought. However, forecasters still haven't officially declared the "child" has arrived, because atmospheric signals still lag behind the ocean temperatures. The chances for an El Niño fully developing are now at 80 percent by fall, NOAA said.

Whether El Niño arrives sooner or later, as the Pacific's oceanic heat wave continues to pump warmth and moisture into the atmosphere, global temperatures will likely continue to rise this year, scientists think. The warmest years in the past decade featured El Niños, and the previous record for warm ocean temperatures in May was set in 1998, another El Niño year.

May's record warmth continues a long-term trend, NOAA said. The last 351 months have been warmer than average, and much of the planet was unusually hot in recent months. Here are some highlights from the NOAA report:

• Australia saw its third warmest May on record, with record highs set in South Australia.
• South Korea sweltered through its warmest May since record-keeping started.
• Alaska had its sixth-warmest May since 1918.
• Scotland had its warmest spring on record.
• Norway also welcomed its warmest spring since 1900, and one of the wettest.

Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on Live Science.

Time to place your bets: The chance of an El Niño developing this year continues to rise, forecasters with the National Atmospheric and Oceanic Administration said today (June 5).

NOAA's Climate Prediction Center (CPC) puts the odds of an El Niño at 70 percent this month and 80 percent during the fall and winter. But it's too soon to officially declare an El Niño, because the ocean and atmosphere are sending mixed signals, the CPC said in its monthly El Niño outlook, released today.

First, a quick definition: An El Niño is part of a natural climate cycle called the El Niño Southern Oscillation. The cycle swings between warmer water (an El Niño) to colder water (La Niña) in the eastern Pacific Ocean. [How El Niño Causes Wild Weather All Over the Globe (Infographic)]

During a potential El Niño year, scientists watch for unusually warm water in the eastern Pacific, along with weakening easterly trade winds, which usually block warm water from flowing toward the eastern Pacific.

Currently, wind and rainfall patterns don't quite match with a maturing El Niño. As warmer water moves eastward, so do the clouds and thunderstorms associated with it. Tropical rainfall patterns still haven't shifted away from Indonesia as expected during an El Niño year, the CPC said. Trade winds haven't slowed down yet, either, though the winds usually don't weaken until fall during an El Niño.

However, even though the atmosphere isn't showing strong signs of an El Niño, ocean temperatures have crossed the threshold that forecasters typically use to define an El Niño, the CPC said. Its latest measurements peg temperature anomalies between 1.1 and 2.9 degrees Fahrenheit (0.6 and 1.6 degrees Celsius), above the 0.9 F (0.5 C) threshold.

The missing atmospheric response to this warm water makes for a tricky forecast. The ocean is clearly heading toward an El Niño, but the atmosphere says "conditions neutral," the CPC said.

The CPC said significant uncertainty accompanies their outlook for strength: forecasters aren't sure whether this year's El Niño will be weak or strong. For now, models call for a moderate-size event.

But forecasters remain "just as confident that El Niño is likely to emerge," the CPC said. 

El Niño is known for moving atmospheric moisture around the globe, causing snowy winters in the Northeast and wet winters in the Southwest. In turn, drought often strikes in Southeast Asia and Australia.

The next El Niño update will be released on July 10.

Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on Live Science.

An endangered species success story is suffering this year, perhaps because of El Niño.

California brown pelicans almost completely failed to breed at their nesting sites in Mexico this year, surveys have found. Scientists are reluctant to blame any one cause for the drastic decline in fuzzy-headed baby pelicans, but a similar drop in breeding numbers struck during previous El Niño events.

"Over the years, we've seen that during an El Niño, their breeding effort goes way down," said Daniel Anderson, a University of California, Davis wildlife biologist who has monitored California brown pelicans for 46 years. Overfishing of sardines and habitat loss could also be hurting the pelican population, Anderson said.

But this year is the biggest drop in baby pelicans Anderson has seen in nearly five decades. [In Photos: Flight of the Brown Pelicans]

"This is about as extreme as we've ever observed," Anderson told Live Science.

Scientists have yet to officially declare an El Niño, but forecasts call for a 78 percent chance of the climatic event occurring by summer.

The pelicans' behavior this year suggests they're already responding to the developing El Niño, Anderson said. "Although the El Niño isn't really full-blown, the birds are starting to show an early effect," he said.

How warm water hurts baby birds

An El Niño is a natural climate cycle that displaces cool water in the Eastern Pacific Ocean with warmer water, which disrupts fish populations. During previous El Niño years, brown pelicans trailed their shifting food supply, flocking to more northerly fishing grounds earlier than usual, studies found.

"Their food migrates, and so they need to track their food," Anderson said.

However, more research is needed to link this year's decline to El Niño. For example, while El Niño conditions favor a boom in sardine populations, anchovies are at a low point in their natural cycle, and the oily fish is a favorite food for breeding brown pelicans, Anderson said.

The low numbers of brown pelican hatchlings suggest a lack of food for adults at the Baja breeding grounds. This spring, if the birds arrived at breeding colonies at all, many abandoned their nests, the survey reports. Roughly 90 percent of California brown pelicans breed offshore of western Mexico.

This year, the brown pelicans migrated to food hot spots along the California coast six weeks earlier than expected, according to the annual population survey led by Anderson.

Breeding numbers are also down to about 1 percent of average, the survey reports. Here are some the findings:

• On Isla Angel de la Guardia, there were only 120 pelican nesting pairs and no hatchlings. In 2006, the survey counted 3,550 nesting pairs and 3,905 young birds.
• On Isla San Luis, there were 465 nesting pairs and 16 young (9 percent of normal). Here, in 2006, the team counted 5,400 nesting pairs and 5,940 young birds.
• On Isla de Piojo, there were 70 nesting pairs and no hatchlings (19 percent of normal), compared with 600 nesting pairs and 660 young birds in 2006.

Expect a rebound

Pelicans are long-lived and breed for decades, so a single year's failure is not likely to impact the population significantly. "Every other time they've bounced back, so we expect them to bounce back again," Anderson said. "That's part of the natural cycle during an El Niño."

However, Anderson notes that the El Niño's effects on fish populations could mean a second year of breeding failure for pelicans. The birds need 100 to 150 pounds (45 to 68 kilograms) of fish for each hatchling over a period of five months.

Brown pelicans were once critically endangered, nearing extinction, because of the effect of the insecticide DDT on their eggs. In the 1960s, biologists noticed the birds were laying unusually thin eggs, and attributed the deformed eggs to DDT. After DDT was banned in the United States in the 1970s, the population recovered, and the iconic bird was removed from the Endangered Species list in 2009.

Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on Live Science.

A massive oceanic heat wave is rolling toward the eastern Pacific Ocean right now, a telltale signal of a brewing El Niño.

An El Niño is a natural climate cycle marked by warmer-than-average temperatures in the waters of the equatorial Pacific Ocean. Forecasters won't make their final call until later this summer, but all signs point to an El Niño this year, perhaps one as powerful as what occurred in 1982 or 1997. But even a weak El Niño could hike global temperatures to record levels, scientists think.

"If we have the El Niño that most are predicting, I think there's a good chance that it'll end up breaking the global temperature record set in 2010," said Andrew Dessler, a climate scientist at Texas A&M University in College Station.

That's because Earth's temperature is already rising, so any year with a boost from El Niño could easily break records. [How El Niño Causes Wild Weather All Over the Globe (Infographic)]

The warmest years in the past decade, 2005 and 2010, followed weak El Niño years, according to NASA temperature records.

This year's predicted El Niño could increase global surface temperatures by 0.18 to 0.36 degrees Fahrenheit (0.1 to 0.2 degrees Celsius), depending on the intensity of the event, said Wenju Cai, a climate scientist at CSIRO Marine and Atmospheric Research, a government research organization in Aspendale, Australia. 

When an El Niño occurs, the equatorial eastern Pacific Ocean experiences several months of higher-than-average sea-surface temperatures. Since 1950, years during or just after an El Niño were hotter than average because this surface ocean warming adds to the planet's overall temperature, according to NASA records.

Here's how it works: An El Niño pumps up heat from deeper ocean layers to the surface. Then, some of the ocean's resulting surface heat is released to the atmosphere, warming the air.

Most of this stored ocean heat comes from sunlight, but the release adds to the overall rise in temperatures caused by global warming, Cai said. "There's no doubt the underlying trend is caused by greenhouse warming," he said.

However, the record-setting temperature record may not occur until 2015. The fever from El Niño tends to lag a few months behind the start of the associated climate event, so the heat may not hit next year. During the 1997 El Niño, the Pacific Ocean heating kicked off in May 1997, but global temperatures peaked in 1998, at four times above average.         

"Usually, the increase occurs more toward the latter part of the El Niño, when there is a mini-global warming," said Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research in Boulder, Colorado.

Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on Live Science.

The El Niño Southern Oscillation (ENSO) is a shift in the jet stream over the Pacific Ocean caused by warmer-than-usual ocean water. It is responsible for severe weather, droughts and other effects worldwide.

El Niño influences global weather by intensifying the Hadley circulation, which transfers heat from the Earth's surface to the upper atmosphere through convection.

A warming trend in the Pacific Ocean occurs at intervals of two to seven years, and typically lasts from nine months to two years. This is called “El Niño.”  A corresponding cooling trend is termed “La Niña.”

El Niño is a change in air pressure between the eastern and western parts of the Pacific Ocean. Low air pressure occurs over warm water, so a warming trend that extends over the entire east-west expanse of the Pacific Ocean will create a large band of low pressure, feeding thunderstorms. The storms form over the usually cool waters off the coast of South America, causing flooding.

Despite its origin in the Pacific, El Niño alters weather patterns across the globe, bringing excessive flooding to some areas and drought to others. Warmer, drier winters are experienced in the northern half of the U.S., while much wetter winters are felt in the southern U.S. and northern Mexico.

The forecast for a drought-busting El Niño this winter has Californians as giddy as kids at Christmas.

An El Niño is the warm phase of a natural Pacific Ocean climate cycle driven by sea surface temperatures. The redistribution of hotter versus colder surface water triggers changes in atmospheric circulation that influences rainfall and storm patterns around the world.

Warm water is piling up in the equatorial eastern Pacific Ocean right now, similar to the pattern that preceded the strong 1997-1998 El Niño, when California was drenched by a series of winter storms. The coming El Niño could finally bring real drought relief to California and other Southwestern states now in severe drought conditions. Based on past events, excess rainfall will also hit southeastern South America and eastern equatorial Africa, according to the National Oceanic and Atmospheric Administration (NOAA). [Infographic: Earth's Atmosphere Top to Bottom]

A new graphic from NOAA details El Niño's global impact on rainfall, from drought in Australia to flooding in India.

As the image shows, the change in global rainfall patterns caused by an especially powerful El Niño won't be welcomed everywhere in the world. The climate phenomenon will also bring drought to Indonesia, northern South America and southern Africa, NOAA said in a statement.

Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on Live Science.

El Niño conditions seem to be developing in the equatorial Pacific Ocean, data from satellites and ocean sensors indicate.

A natural climate cycle that brings abnormally toasty temperatures to the Pacific Ocean, El Niño occurs when winds pile up warm water in the eastern part of the equatorial Pacific, triggering changes in atmospheric circulation that affects rainfall and storm patterns around the world. 

Sea-surface height can reveal if such heat is being stored in particular regions of the ocean, since water expands as it warms. Above-normal sea-surface height in the equatorial Pacific Ocean, in turn, can suggest an El Niño is developing, according to NASA's Earth Observatory. That's what is showing up right now, as satellite images taken from the Ocean Surface Topography Mission/Jason 2 satellite reveal sea-surface height, averaged over a 10-day period centered on May 3, is above normal. A similar anomaly showed up during May 1997 — which coincided with one of the strongest El Niños ever experienced. That year North America saw one of its warmest and wettest winters on record; Central and South America saw immense rainstorms and flooding; and Indonesia along with parts of Asia endured severe droughts, the Earth Observatory noted. [See 101 Stunning Images of Earth from Space]

"What we are now seeing in the tropical Pacific Ocean looks similar to conditions in early 1997," said Eric Lindstrom, oceanography program manager at NASA headquarters, in an Earth Observatory statement. "If this continues, we could be looking at a major El Niño this fall. But there are no guarantees."

A network of sensors in the Pacific Ocean reveals a deep pool of warm water shifting eastward, supporting the satellite data, according to the Earth Observatory.

Model predictions issued on May 8 by the National Weather Service Climate Prediction Center forecast that the chances of an El Niño developing during the summer are more than 65 percent. "These atmospheric and oceanic conditions collectively indicate a continued evolution toward El Niño," the alert read.

This event may be just the beginning of more intense El Niños to come, according to research detailed Jan. 19 in the journal Nature Climate Change. That study suggested the most powerful El Niño events may occur every 10 years rather than every 20 years, due to rising sea-surface temperatures overall in the eastern Pacific Ocean.

Follow Jeanna Bryner on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on LiveScience.