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Antarctica could melt 'irreversibly' due to climate change, study warns

Antarctica minus ice
A simulation shows Antarctica, totally stripped of ice.
(Image: © Garbe et al.)

Antarctica contains more than half of the world's freshwater in its sprawling, frozen ice sheet, but humanity's decisions over the next century could send that water irreversibly into the sea.  

If global warming is allowed to continue unchecked, Antarctica will soon pass a "point of no return" that could reduce the continent to a barren, ice-free mass for the first time in more than 30 million years, according to a new study published Sep. 23 in the journal Nature.

"Antarctica is basically our ultimate heritage from an earlier time in Earth's history. It's been around for roughly 34 million years," study co-author Anders Levermann, a researcher at the Potsdam Institute for Climate Impact Research (PIK) in Germany, said in a statement. "Now our simulations show that once it's melted, it does not regrow to its initial state [until] temperatures go back to pre-industrial levels … a highly unlikely scenario. In other words: What we lose of Antarctica now, is lost forever."

Related: 6 Unexpected effects of climate change

In the study, PIK researchers ran computer simulations to model how Antarctica will look thousands of years from now, depending on how high average global temperatures rise in response to modern greenhouse gas emissions.

They found that, if average temperatures rise 7.2 degrees Fahrenheit (4 degrees Celsius) above pre-industrial levels for any sustained period of time, much of the ice in West Antarctica will crumble, resulting in 21 feet (6.5 meters) of global sea-level rise; that amount of rise would devastate coastal cities like New York, Tokyo and London. This scenario could be a reality within decades; a global average temperature rise of 9 F (5 C) is currently considered the “worst-case” warming scenario if current greenhouse gas emission levels are allowed to continue through the year 2100, according to the UN’s Intergovernmental Panel on Climate Change (IPCC).

If those IPCC projections are off, things could get much, much worse, the authors of the new study found. Should global temperatures rise between 11 and 16 F (6 to 9 C) above pre-industrial levels for any sustained period of time over the coming millennia, more than 70% of Antarctica's present-day ice will be lost "irreversibly," the study authors wrote. And, if temperatures rise by 18 F (10 C), the continent is doomed to be "virtually ice-free." Should the continent lose all of its ice, global sea levels will rise by nearly 200 feet (58 m).

A short video accompanying the study (shown here) illustrates that reality in grim detail, showing the continent's ice vanishing first from the coasts, then all across the mainland until nothing but green plains and rocky cliffs remains.

This cataclysmic melting will not occur in our lifetimes; the full effects would likely not be seen for roughly 150,000 years, Andrew Shepherd, a climatologist from the University of Leeds in the United Kingdom, who was not involved in the study, told the Daily Mail

However, the study authors warned, humankind's failure to reduce greenhouse gas emissions this century could trigger an irreversible feedback cycle that seals Antarctica's fate for millennia to come. 

The rapid depletion of Antarctica's ice shelves — large plates of ice anchored to the mainland on one side and floating freely over the ocean on the other — represent one particularly dangerous feedback mechanism, the researchers wrote. As warm ocean water laps against the underside of ice shelves, the point where the base of the shelf meets the water (also called the grounding line) retreats farther and farther back, destabilizing the entire shelf and allowing enormous chunks of ice from the mainland to slide into the ocean. Many ice shelves in West Antarctica are already experiencing this sort of runaway melt, with roughly 25% of the region's ice in danger of collapsing, according to a 2019 study in the journal Geophysical Research Letters.  

Antarctica's fate is in the hands of current policymakers, the study authors concluded. The Paris Climate Accord, which 73 nations agreed to in 2015 (and which the United States abandoned in June 2017 at the behest of President Donald Trump), aims to limit the planet's average temperature from rising by more than 2.7 F (1.5 C) above the preindustrial average, to forestall the worst effects of climate change.

While emissions dropped by a trivial amount earlier this year, due to mass quarantining during the pandemic, a UN report published earlier this month warns that the world is currently not on track to meet the goals laid out in the Paris Accord, with average global temperatures lingering around 2 F (1.1 C) above pre-industrial levels between 2016 and 2020.

The report added that there's a 20% chance the annual global mean temperature will have increased by more than 2.7 F (1.5 C), at least temporarily, by the year 2024.

Originally published on Live Science.

  • Edward
    And, if temperatures rise by 18 F (10 C), the continent is doomed to be "virtually ice-free." Should the continent lose all of its ice, global sea levels will rise by nearly 200 feet (58 m)

    Ohhhh Scary. "Doomed" note the word doomed above. What's your fascination with ice? You would rather have a useless continent covered with ice than covered with green plants? I think your priorities are nuts.

    Lake Ontario's altitude is 257 ft above present sea level therefore in the worst case Toronto is OK and everything around lake Ontario. We're OK, don't worry about us!
    Reply
  • hellopunyhumans
    Edward said:
    And, if temperatures rise by 18 F (10 C), the continent is doomed to be "virtually ice-free." Should the continent lose all of its ice, global sea levels will rise by nearly 200 feet (58 m)

    Ohhhh Scary. "Doomed" note the word doomed above. What's your fascination with ice? You would rather have a useless continent covered with ice than covered with green plants? I think your priorities are nuts.

    Lake Ontario's altitude is 257 ft above present sea level therefore in the worst case Toronto is OK and everything around lake Ontario. We're OK, don't worry about us!
    And new york city, a city of 8.4 million, would be under over 150 feet of water in most areas.
    Reply
  • Douglass Allen
    Science data matters. I teach a course in climate science in the OLLI program at Furman U.
    The article title uses the word "could". Here's the current data for the Antarctic Ice Extent, well above the 30 year 1981 to 2010 average-https://i2.wp.com/nsidc.org/data/seaice_index/images/daily_images/S_timeseries.png?ssl=1
    Reply
  • tgimacbNM
    Apparently, the genius of that community organizer is as valuable as the Nobel prize for Drone mass murder!
    "if average temperatures rise 7.2 degrees F (4 degrees C) above pre-industrial levels for any sustained period of time, much of the ice in West Antarctica will crumble, resulting in 21 feet (6.5 meters) of global sea-level rise; that amount of rise would devastate coastal cities like New York, Tokyo and London AND MARTHA'S VINEYARD ISLAND PRIVATE COMPOUNDS
    (What tha gon do? SCUBA from the bedroom Trump pissed on, to the kitchen?)

    jUST call it global warming again
    Reply
  • tgimacbNM
    tgimacbNM said:
    Apparently, the genius of that community organizer is as valuable as the Nobel prize for Drone mass murder!
    "if average temperatures rise 7.2 degrees F (4 degrees C) above pre-industrial levels for any sustained period of time, much of the ice in West Antarctica will crumble, resulting in 21 feet (6.5 meters) of global sea-level rise; that amount of rise would devastate coastal cities like New York, Tokyo and London AND MARTHA'S VINEYARD ISLAND PRIVATE COMPOUNDS
    (What tha gon do? SCUBA from the bedroom Trump pissed on, to the kitchen?)

    jUST call it global warming again
    Reply
  • Ron McCune 2
    admin said:
    Antarctica could be completely ice-free one day if we allow climate change to continue unabated.

    Antarctica could melt 'irreversibly' due to climate change, study warns : Read more
    Folks, I got some really bad news for all of you. You're screwed! Read facebook.com/ron.mccune.3 and see why in about 15 years the North pole will be completely melted and about 5-10 years after that the South Pole will be completely melted as will all the Earth's glaciers and snow covered mountains. The Earth will have no more winters as insects enjoy a longer lifespan and make your lives 1000% more miserable. Global warming caused the weakest chain in the Earth's ice systems, permafrost, to for some odd reason start to melt rapidly in the early 1960's. China industrial growth, Putin's KGB minded tricks to increase warmer climates over Russia through his inaction on controlling fires in the permafrost areas and polluting the waters of Russia so that weather patterns in Russia were worsened and Putin and Russia's yearly flyover of Russia's five time zones massive amounts of military planes and equipment which yearly adds a blanket of hot air over Russia and that part of the world. Since the 1960's melted permafrost water, which now is warmer than ice, has been draining into the Arctic Ocean where it has been melting the ice in the North Pole. As that now warmer waters from the North pole circulated around the world it warmed the oceans and worse of all the waters around the South pole where it has been melting water ever since. That's how global warming started! Read facebook.com/ron.mccune.3 to see how global warming started and how to end it! But continuing as the Earth progresses from today's climate pattern of more water in the oceans creating more severe storms now and for a while in the oceans and in certain areas of the Earth most of the Earth will see drier, hotter weather with few clouds. What clouds are to be seen won't produce rain as the Earth swelters in heat from that gigantic ball of fire miles away called the Sun which is shooting hot deadly rays and pouring heat onto our planet! Fortunately since the beginning of life on Earth nature had created the one and only thing that could shield the planet from these deadly hot Sun rays and that was clouds. Clouds are Earth's umbrella from the Sun. Without clouds the Sun will bake all live from the surface of the planet. Without clouds there would be no water. Clouds are the only thing on Earth that creates water. No clouds, no life! In about 25-35 years all of you on Earth will be witnessing the end of civilization as we know it as the Sun will begin it's unchallenged task of baking the life off the face of Earth, a planet that no longer produces clouds or rain. I will say your only chance for survival is to now and especially in about 10 years to numerous times shoot somehow massive amounts of volcano ash into the sky from numerous spots on the Earth to help Earth to provide the only other thing besides clouds that can can shield the Earth from the hot rays of the Sun! Or you can all go live underground and hide from the Sun. But your water will evaporate so cover it all up! Find underground rivers! but your biggest problem will be food! There will be no way to feed everyone because you won't be able to farm anymore! That is the future all of you face in about 20 years!
    Reply
  • Broadlands
    ""Antarctica is basically our ultimate heritage from an earlier time in Earth's history. It's been around for roughly 34 million years,"

    Yes, 33 million years ago the Antarctic ice sheet began to form. What's missing is the fact that at that time atmospheric CO2 was more than double what it is today and began to drop. The late Eocene climate was mild. There was no catastrophic change in the climate. Life on land was lush and the marine carbonate plankton flourished even though the pH was lower than today. The future here will not be what climate models forecast. The geological and geochemical evidence from the past is a preview.
    Reply
  • Choppa
    This is great news now billionaires will have more oceanfront property to destroy
    Reply
  • Broadlands
    Actually, Ed.. You don't have to be a billionaire to own coastal properties that the climate forecasts of a rapidly rising ocean would destroy. The great news is it won't happen anytime soon.

    "This cataclysmic melting will not occur in our lifetimes; the full effects would likely not be seen for roughly 150,000 years, Andrew Shepherd, a climatologist from the University of Leeds in the United Kingdom, who was not involved in the study, told the Daily Mail. "
    Reply
  • jaznm
    Has anyone ever thought that the present trend of posibive temperature feedback could suddely reverse? thoughts?
    Reply