Expect More Giant Snowstorms as Climate Warms

Even though ferocious snowstorms will become more frequent this century, their intensity will stay the same.

(Image credit: Glacier National Park)

Marlene Cimons writes for Climate Nexus, a nonprofit that aims to tell the climate story in innovative ways that raise awareness of, dispel misinformation about, and showcase solutions to climate change and energy issues in the United States. She contributed this article to Live Science's Expert Voices: Op-Ed & Insights.

The storms that buried the Buffalo, New York, area in more than 7 feet (2.1 meters) of snow this week shattered records and shocked residents — even in a region accustomed to dealing with heavy snow. The storms are certain to provide new fodder for climate-change skeptics who seem to embrace every monster blizzard as evidence that global warming doesn't exist.

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"Part of what gave us the record lake-effect snowfall in Buffalo was warm, late-fall lake-surface temperatures that combined with something highly unusual: a 5 sigma event. That is, a very unlikely event on the order of 1-in-a-million — a remarkably persistent, anomalous configuration of the jet stream, which brought frigid Arctic air down into the United States so early in the season," said Michael Mann, professor and director of the Earth System Science Center at Pennsylvania State University. "The cold winds traveling over the warm moisture-laden lake created a perfect storm of conditions for record lake-effect snow."

The basic science behind snow and its relationship to climate change is fairly straightforward. Warmer temperatures cause more water to evaporate into the atmosphere, and warmer air holds more water than cooler air. The air's water-holding capacity, in fact, rises about 7 percent with each 1 degree Celsius (1.8 degrees Fahrenheit) of warming. The warming results in air that becomes supersaturated with water, often bringing drenching rainfall, followed by flooding or, if it is cold enough, heavy and intense snowfall. [Snow in Spring? Why a Cold March Doesn't Disprove Global Warming ]

A study of 20th c entury snowstorms published in the August 2006 issue of the Journal of Applied Meteorology and Climatology, before the big storms of recent years, found that most major snowstorms in the United States occurred during warmer-than-normal years. The climatologists who authored the paper — the late Stanley Changnon, a scientist with the Illinois State Water Survey, David Changnon, a professor with the Northern Illinois University department of geography, and Thomas R. Karl director of the National Oceanic and Atmospheric Administration’s National Climatic Data Center — predicted that "a warmer future climate will generate more winter storms.''

That outcome was especially dramatic in 2010, when storms walloped the Atlantic states — most notably, a back-to-back punch only one day apart in February of that year that broke records in many major cities and, in Washington, D.C., became known as "Snowmageddon.'' Rare storms also brought heavy snows to the Deep South, including the northwestern panhandle of Florida. In fact, by the second week of February, every state but Hawaii had snow on the ground.

Since 1950, in fact, there have been signs of an increase in lake-effect snowfall along and near the southern and eastern shores of the Great Lakes, according to the United States Global Change Research Program. (USGCRP). Such snow results from the strong flow of cold air across large areas of relatively warmer ice-free water. Ice coverage on the Great Lakes has dropped with the warming climate, creating conditions favorable to more evaporation and heavier snowstorms. Western New York, for example, also experienced extreme lake-effect snow in February 2007, when more than 10 feet (3 m) of snow fell during a 10-day period. At least one study shows how lake-effect snow storms increase with global warming.

On the surface, it almost seems contradictory — although, in reality, it is not. On one hand, warming temperatures are leading to milder and shorter winters in most areas, including a later start to winter and earlier onset of spring. During the past 30 years, temperatures have risen faster in winter than in any other season, with average winter temperatures in the Midwest and northern Great Plains increasing by more than 7 F (4 C), according to the USGCR.

"If you look at model projections of climate change for the next few decades under 'business as usual' carbon emissions, what they show is that you'll still have 'winter' over regions like the United States — that is, there will still be a wide seasonal window where it is cold enough for snow,'' Mann said. "But because winters will be warmer, the atmosphere will have the ability to hold more water vapor, and so there is more of that water vapor available for precipitation. Again, as long as it's cold enough for that precipitation to be snow, which it will be, you'll actually get larger snowfalls.''

Average precipitation projections for the future are going both up and down, depending on the region. In high latitudes, especially in the far North — Siberia, Canada and the northern United States — precipitation is expected to increase during winter and spring. That is due to both the water-holding capacity of the air and circulation changes that drive greater moisture from the tropics into higher latitudes, Wehner said.

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