Ecocentric

Antarctica Melted in the Past, and As the Climate Warms, It’s Poised to Melt Again

The South Pole has been the stable one in the climate change era—relatively speaking. But a pair of studies about Antarctica's past and its present point towards a very different future.

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Michael Leggero / Getty Images

Antarctica hasn't experienced the rapid melting that the Arctic has, but that is changing

When it comes to polar melting, the Arctic hogs all the attention. And not without reason—last summer Arctic sea ice melted to its smallest extent on record, 49% below the 1979-2000 average. During the first two weeks of July, sea ice declined 61% faster than the 1981-2000 average, according to the National Snow and Ice Data Center. As sea ice melted, Arctic shipping set a record, with trips quadrupling in 2013 from the year before. The Arctic permafrost—the frozen soil that covers much of the tundra—is melting, which threatens the release of vast amounts of the greenhouse gas methane. Thanks largely to climate change, the Arctic is changing before our very eyes.

The Antarctic, on the other end of the globe, is pretty boring by comparison. Antarctica is losing ice, but not as fast or dramatically as the Arctic is. Relatively little warming has occurred to change the endless ice sheets of Eastern Antarctica, which contain enough frozen water that sea levels would rise by nearly 200 ft. if it all melted. Ice sheets break off in Western Antarctica, which is really more of a series of frozen islands, but altogether the rate of change has been more gradual in the forbidding and largely uninhabited South Pole.

But Antarctica hasn’t always been so relatively stable—and it won’t remain that way in the future.


(MORE: Studies of the Past Show an Ice-Free Arctic Could Be in Our Future [UPDATE])

A new study in the journal Nature Geoscience suggests that large of the East Antarctic Ice Sheet experienced significant melting during the Pleistocene Pliocene epoch*, between 5.3 and 2.6 million years ago, when atmospheric levels of carbon dioxide were similar to where they are today, and temperatures were about 2 to 3 C warmer than they are now. It was a time when sea levels were some 66 ft. higher than they are today—more than high enough to swamp coastal cities. While scientists knew that all of Greenland and West Antarctica had to be ice-free at the time, the sediment data in the Nature Geoscience shows that the East Antarctic ice sheet must have retreated a couple hundred miles inland. “The East Antarctic Ice Sheet has been much more sensitive to climate change in the past than previously realized,” said the study’s lead author, Carys Cook of Imperial College London, in a statement.

In another study, researchers from the University of Texas at Austin found that coastal Antarctic permafrost—which, unlike Arctic permafrost, was considered to be stable—is actually melting much faster than scientists had expected. Researchers had though that the permafrost in the region was in equalibrium—ice would melt during the summer, only to refreeze in the winter. But the Texas study, published in Scientific Reports, shows a rapid melting of permafrost in Antarctica’s Garwood Valley, diminishing the overall mass of ground ice. “The big tell here is that ice is vanishing—it’s melting faster each time we measure,” said Joseph Levy, a research associate at the University of Texas’s Institute for Geophysics and the lead author on the paper.
“That’s a dramatic shift from recent history.”

It’s important to note that global warming is not responsible for the permafrost melt here—that region of Antarctic actually experienced a cooling trend from 1986 to 2000, followed by relatively stable temperatures. The Scientific Letters researchers suggest instead that the melting is due to an increase in radiation from sunlight resulting from changing weather patterns that allow more light to reach the ground during the summer. (In the winter, of course, Antarctica experiences 24-hour darkness.) As the permafrost melts, it actually alters the land surface, creating “retrogressive thaw slumps.” The changes observed in the study are occurring around 10 times faster than the average during the Holocene, the current geological epoch, and can actually be seen with time-lapse photography:

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University of Texas at Austin, Institute of Geophysics

 

Climate models expect Antarctica to warm in the decades to come, which means melting and land change are likely to accelerate. The Arctic has been unstable for years, but for as long as researchers have been concerned about climate change, Antarctica has been relatively steadfast. But it looks like that’s about to change.
(MORE: All Eyes on the World: A Look Back at NASA’s Best Views of Earth)
*[Updated with the correct epoch]
10 comments
SeanMaddox
SeanMaddox

Well, conservatives continue their death spiral, and now they're pulling everyone else in America and the world into it too with their utter denalism of basic science. Thanks Saint Reagan paving the way and getting a whole special breed of imbeciles to run for and get into political positions.

LeslieGraham
LeslieGraham

Lord knows which denierblog he got that 77% figure from but it's simply laughable junk.

2013 is very close to 2012 as anyone can see in ten seconds on Google. Todays measurement from JAXA is at 7,303,281 km2. This time last year the extent was around 7,300,000km2.

But in any case the melting trend is accelerating and the Arctic summer ice is really as good as gone - it's just a matter of a few years or, at most, a couple of decades. It just beggars be3lief that with all the amazing technology we have, including the GRACE 2 sattelite prviding info in real time, that there are still a few of these total whackjobs parroting such absurd nonsense.

Here's JAXA's website. There are others too. http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

And anyone who has the slightest doubt just how rapidly the ice volume is disapearing as we watch just check out this 30 second video of the last 30 odd years.

http://www.youtube.com/watch?feature=player_embedded&v=YgiMBxaL19M

MichaelJones
MichaelJones

I think we should discuss this further (just so we don't have to actually do anything about it).

ShawnArscott
ShawnArscott

IS this the reason why the Queen claimed millions of acres in the Antarctic last year?

ProdigalPotter
ProdigalPotter

According to today's NOAA satellite measurements, the Antarctic icepack is 107% of its average size over the last 30 years (13.4/12.5 million sq km), unsurprisingly so as it has remained above 100% every day for the last 15 months. The record drop in Arctic ice last year (62.5% of normal) is now being followed by a resurgence in icepack resilience with today's NOAA measurement showing a growth of 77% on this day last year. Failing to provide data when discussing a measureable phenomenon is just bad journalism.

BryceBaensch
BryceBaensch

@SeanMaddox  Lets all be ignorant and have 2 "sides" then we can sit here and blame each other while real problems go unsolved... Ignorance at its best.. both republicans and democrats.  Monastery thanks for your comment. 

monastery
monastery

@SeanMaddoxYou and the left are loons. Both poles are in constant flux. That's a geological truth. You can't look at them through a tiny sliver in time. And don't insist that you know what the poles looked like, year to year, in the early part of the 20th Century.

Liberals proclaimed in the 1980s that humanity was instigating a new ice age. (Are you even old enough to remember that mania?) And you all called Conservatives idiots who were in denial.

We were right then and we're right now. The world is eternally in flux.

cjh2nd
cjh2nd

@MichaelJones  

here here. why act when we can talk about acting? much easier that way

ConstantGardener
ConstantGardener

@ProdigalPotter  Last year was the worst year for ice loss in the Arctic.  In addition to global heating, there was a storm in the Arctic that played a role in dispersing ice.  The smart question, the meaningful question to ask, is how does 2013's ice melt compare to the average ice melt?  Compared to the 1981 to 2010 average, ice extent on July 15, 2013 was 1.06 million square kilometers (409,000 square miles) below average.

People who cherry pick data ought not complain about journalism.

jimbenison
jimbenison

@ProdigalPotter Antarctica is losing about 100 cubic kilometers of ice each year (the grounded kind that raises sea levels). The rate of loss has tripled since the 1990's. This is according to satellite data from GRACE. If you want to dispute that perhaps you should build a pair of satellites capable of subtle changes in the earth's gravity and let us know what you find.

The people who are smart enough to build and launch these satellites say it's happening and they are concerned enough about it to study it. Now let's hear you go off on how it's about getting funding. After all, what would rocket scientists do if there was no global warming? They'd just be destitute living on the streets? Maybe they'd just apply for a high paying job at SpaceX or do one of the many other things that they are obviously smart enough to do.