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Soaring Temps in West Antarctica May Fuel Sea Level Rise

Temperatures in West Antarctica are have increased by 4.3°F over the past 50 years or so, according to a new paper released Sunday in Nature Geoscience. That increase is far more than scientists have thought, and nearly as much as the 5°F rise on the nearby Antarctic Peninsula, the fastest-warming region on Earth.

It’s a cause for serious concern, say the study’s authors: West Antarctica holds enough fresh water to raise sea level by 11 feet if all the ice melted, and even a fraction of that amount could prove catastrophic to coastal areas where hundreds of millions of people live.

Credit: University of Washington

In fact, the 8 inches or so of sea level rise the world has experienced since 1900 is already enough to have boosted the power of storm surges, put pressure on infrastructure in places like South Florida and exposed millions of Americans to the danger of coastal flooding. The 3 feet of additional rise expected by 2100 will make all of these problems vastly worse.

West Antarctica currently adds just a tenth of the current .18 inches of annual sea level rise scientists have measured. But, “if this trend continues, its contribution to sea level rise, could become significant. Not today or tomorrow, but a few decades in the future,” said lead author David Bromwich, of Ohio State University, in an interview.

The reason Bromwich and his colleagues set out to analyze West Antarctic temperature trends is that previous studies have disagreed about what’s happening in that part of the continent. That’s because there are fewer than 20 weather stations in all of Antarctica, whose vast land area equals that of the continental U.S. AND Mexico, so scientists have to make educated calculations about what’s happening in between.

That is less of a problem on bigger, colder East Antarctica, where even a significant temperature increase wouldn’t push the mercury above the freezing point. In the west, though, the ice is already somewhat unstable since much of it sits on land that’s below sea level.

Relatively warm ocean currents have already started eroding the ends of glaciers from below, allowing the ice to flow faster toward the sea. On the Antarctic Peninsula, meanwhile, ice shelves have abruptly collapsed, and in this case, much of the damage has come from meltwater on the surface. “Melting does bad things to ice shelves,” Bromwich said in an understatement.

What’s happening to temperatures in West Antarctica, therefore, could have a big effect on the ice, so Bromwich and his colleagues set out to do a new analysis. There is a weather station in that part of the continent, but temperatures haven’t been taken consistently since the station was established in the late 1950s.

To fill in the gaps, the scientists used a technique known as weather reanalysis, in which climate models predict what temperatures should have been in various places around the globe. Then the models are tested against what actual temperatures were, and refined.

The result is a set of temperature reconstructions that can fill in gaps in the actual record with relatively high accuracy. “It was a big detective undertaking. We think the errors are quite small,” Bromwich said.

The scientists found that winter and spring temperatures rose the most over the 50-year period they studied, but summer temperatures rose as well. Most of the time, they didn’t quite get above freezing, but Bromwich said, “we’ve seen some years when satellites have showed extensive melting” — something like the surface melting seen last summer in Greenland, where temperatures year-round have always been significantly higher than in West Antarctica.

“The point is that the closer you get to freezing, the more likely you are to cross that threshold,” Bromwich said.

And while Bromwich noted that “the Arctic has gotten a lot of attention this year,” in coming years, the world’s attention may be focused on the opposite end of the globe. 

Related Content
As Effects of Warming Grow, U.N. Report is Quickly Dated
Report: Most Antarctic Peninsula Warming Human-Caused
Antarctic Ice Shelves Melting from Below, Study Finds
Greenland Melt Sets Record Weeks Before Summer Ends
It's Official: Arctic Sea Ice Shatters Record Low
Sandy’s Storm Surge Explained and Why It Matters 
The Future is Now for Sea Level Rise in South Florida

Comments

By Dave (Basking Ridge, NJ 07920)
on December 23rd, 2012

The WAIS is not 100% land ice and so there’s a difference between the effects of disintegration and melting. It is not clear to me that the 11 foot SLR statement is numerically correct for melting. However it seems like a moot point to me if one considers that if the West Antarctic ice sheet melts completely then it is seriously unlikely that for instance the East Antarctic Ice sheet will not have experienced a significant degree of melting as well - and it holds the lion’s share of all the ice on the planet.

By the way, regarding “The 3 feet of additional [sea level] rise expected by 2100 will make all of these problems vastly worse.”

I have noticed that the media, including CC, often cite this three feet number. The fact is that there really is a lot of uncertainty over just what SLR will be in the future and I think that it’s about time reporters tried to convey that idea. Serious scientists the world over think it really could also be a lot more than 3 feet. For instance, the most frequently cited current sea level rise projection range that I have seen in the journal literature seems to be 0.8 to 2m by 2100, which is a range of 2.6 to 6.6 feet.

Reply to this comment

By tom (pretoria)
on July 11th, 2013

when the large lakes and rivers started to dry up on western asia they also said it would take a very long time for all the water to disapear. well its all gone in less than 4 decades.

water especialy see water and currents happen to be a funny thing when its loose to go where it wants. more water due to melting in the artic would mean more water at the eqautor which means that that more water have to go somewhere which means more hot tropical water currents back to the antartic as the northen hemisphere has lots of land,eurasia north america, whilst the dynamics for the antaric region happens to be oseanic of nature.
dont they take all of this into account?

warm air cools quickly. warm sea currents creates vast regions of change and thats what is either happening or will happen bound to happen soon.

then things will happen very quickly i think.

also the release of ice cap weight on the antartic shelf will reignight that regions vast unstable volcanic regions inland. that will have an effect 2 miles down that nobody would even know about until its too late. not that anything can be done about it anyway.

hav fun!!!

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