Antarctic Sea Ice Grows Despite Global Warming—But It Won’t Last

By Andrew Moseman | August 17, 2010 11:07 am

Mount_William_AntarcticaScientists have suggested for years now that the effects of a warming planet won’t show up in a uniform fashion across the globe—different locations won’t see glaciers retreat or sea levels rise at the same rate. Some places are particularly confusing because they show signs that seem backward to one’s expectations for a hotter Earth. One of the those confusing outliers for climatologists has been the sea ice off Antarctica.

While the amount of sea ice in the Arctic has been trending downward, Antarctic sea ice has actually expanded even as the area has warmed (and as ice shelves collapsed on the continent). This week, in the Proceedings of the National Academy of Sciences, Jiping Liu and Judith Curry put forth an explanation for this paradox. But, they say, the ice growth probably won’t continue.

Liu and Curry looked through 60 years of temperature and precipitation readings to find an explanation for the increase of sea ice in the warming world, and showed that precipitation increased over Antarctica from 1950 to the the present.

The finding makes intuitive sense: Rising temperatures increase the amount of moisture in the air, which eventually becomes snow. And for the last few decades, that snow kept surface waters from warming even more, added bulk to sea ice, and reflected sunlight [Wired.com].

In addition, the extra fresh water that fell as precipitation would have lowered the salinity of the surface water, the scientists say, and that would have slowed the rate of ice melt:

More snow made the top layers of the ocean less salty and thus less dense. These layers became more stable, preventing warm, density-driven currents in the deep ocean from rising and melting sea ice [National Geographic].

The ice growth, though, may not have staying power. Liu and Curry expect precipitation to continue to increase over Antarctica’s edge in the near-term future, but they expect that precipitation to turn from snow to rain. If that happens, the trend with Antarctic sea ice would reverse as rainfall would begin to melt the sea ice. Losing sea ice feeds into a feedback circle: With less surface ice to reflect away the sun’s rays, the ocean warms even more.

Not all climatologists are convinced by the details of Liu and Curry’s explanation, with some asking whether they factored in the influence of the ozone hole; others, like Doug Martinson, wonder how possible it is to model the fine details of the Antarctic climate system. What is clear, though, is that we shouldn’t be surprised that sea ice near the north pole and the south pole act differently.

The Arctic and the Antarctic are very hard to compare, Martinson said, which is why work like that Liu and Curry are undertaking is important. “They are apples and oranges,” Martinson said. “They are dramatically different systems.” In one case, there is an icy ocean surrounded by land. In the other, there is an icy continent surrounded by icy water [Discovery News].

Related Content:
DISCOVER: It’s Getting Hot in Here, Judith Curry and Michael Mann battle over on the state of climate science
DISCOVER: Antarctica’s Hot Spot
80beats: Robot Sub Dives Deep for Clues To a Fast-Melting Antarctic Glacier
80beats: An Iceberg the Size of Luxembourg Breaks Free from Antarctica
80beats: Antarctica Was an Oasis for Life During “Great Dying” 250 Million Years Ago

Image: Wikimedia Commons

CATEGORIZED UNDER: Environment
  • Carddan

    And as the Antarctic ice recedes, the Arctic ice will increase. It’s been that way for millions of years.

  • FrankP

    No it hasn’t; that’s completely wrong. For the last 2 million years or more we’ve been having an ice age every 110,000 years or so. It’s called the Milankovitch cycle; google it. Always the temperature has driven the CO2 levels but now, for the first time, the CO2 level is completely out of equilibrium with the temperature. The planet will come to equilibrium eventually and it may not be very comfortable for us. It’s probably too late already to try to fix it. Hang on for ride!

  • m

    *rolls eyes at frankp*

    i especially love the part about how when the sea ice melts that sea water will rise.

    archemedes principle!!! a guy over 2,000 years ago in sandals figured it out….who never even saw a glacier, let alone Antartica.

    CO2 is not a greenhouse gas. never was…never will be. CO2 is opaque to IR wavelengths…everyone knows that IR energy wont leave. But hey! gues what?!! because E=mc2, no new energy comes in either.

    people need to read books…not burn them.

  • Alec aka Daffy Duck

    The ice would also have to go out (disappear) faster and earlier. Snow is a great insulator as they mention, just ask anyone in the lake country in the north. When it snows early on ice the snow insulates the ice from the cold and the ice doesn’t thicken…not safe for ice fishing. In the Spring the ice goes out quicker than split! The theory should show very rapid and early melts compared to average for the theory to hold.

    Antarctic ice melt: Spring 2007-2008 & 2008-2009 vs 1979-2000 average.
    http://www.mcculloughsite.net/stingray/assets_c/2008/12/antarctic_sea_ice_2008_12-20-thumb-400×320.png

    This does not match snow.

  • Ordinary Fool

    ‘Apples = Oranges’ thinking produces great irony. Insisting that increasing Antarctic sea ice must mean its colder, when the nearby land ice is all decreasing.

    The Antarctic Peninsula and West Antarctica are losing ice through melting and dynamic movement. Even East Antarctica is now in a net ice mass loss.

    Archimedes would worry.

  • Brian Too

    3. m,

    I am sorry to inform you that you are Not Even Wrong.

  • Ordinary Fool

    Apples=Oranges……….Another obvious indicator of the weakness of the attempted Arctic/Antarctic sea ice relationship is the absence of any scientific support (paper or person).

    That the Antarctic sea ice extent increases, despite higher temperatures both above it and below it, is described as confusing or puzzling or a paradox. It is not seriously described as being contested.

  • Dan C

    An increase in wind would explain the increase in sea ice, also, and the increase in wind would fit with warmer climate.

    m: You’re correct, the CO2 blocks IR wavelengths. Unfortunately, more energy comes in from the sun in the higher wavelengths as light, gets absorbed by surfaces and lower atmosphere(dust, etc), then gets re-radiated as heat (IR wavelengths), which get blocked by the CO2 and sent back to earth. That’s why it’s called a “Greenhouse” effect. My greenhouse gets warmer than ambient inside even when the sun is behind clouds and I don’t feel any heat from it outside the greenhouse in winter. The visible light is the difference (UV is blocked by the plastic’s protective coating).

    In other words, you missed a step of the process that often confuses people. Don’t feel bad.

  • FrankP

    Dan C – you’re exactly right. I’m glad that some people are paying attention and learning! And I hope it’s not already too late to fix it!

  • robert

    i especially love the part about how when the sea ice melts that sea water will rise.

    archemedes principle!!! a guy over 2,000 years ago in sandals figured it out….who never even saw a glacier, let alone Antartica.

    CO2 is not a greenhouse gas. never was…never will be. CO2 is opaque to IR wavelengths…everyone knows that IR energy wont leave. But hey! gues what?!! because E=mc2, no new energy comes in either.

    people need to read books…not burn them.

    The person who wrote this comment should indeed read a little more. The sun, due to the temperatures of its photosphere does not emitt much IR radiation. On the other hand the earth does. Almost all incoming solar radiation is converetd to IR and this is absorbed by CO2. Thus, this energy stays in the atmosphere to a greater extent in the presence of higher CO2 levels.

  • http://blogs.discovermagazine.com/80beats/ Eliza Strickland

    Just FYI, Robert — This post isn’t about sea level rise. It’s explaining a study that just deals with precipitation and sea ice.

    It’s well understood that melting sea ice doesn’t raise sea levels much; just like ice cubes in a glass of water don’t cause the glass to overflow when they melt. It’s the melting and runoff of land-based glaciers and ice sheets that really increases water volume in the ocean.

    There’s a little wiggle room in that statement because researchers recently determined that melting icebergs have a small effect on sea levels, because sea water is warmer and more salty than floating ice. The change in density and temperature raises sea levels very slightly.

    — Eliza, DISCOVER online news editor

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