Climate scientists have long believed that while most of the rest of the globe has been getting steadily warmer, a large part of Antarctica — the East Antarctic Ice Sheet — has been getting colder.
But new research, depicted in this illustration released by NASA today, shows that for the last 50 years, much of Antarctica has been warming at a rate comparable to the rest of the world.
“In fact, the warming in West Antarctica is greater than the cooling in East Antarctica, meaning that on average the continent has gotten warmer,” said Eric Steig, a University of Washington professor of Earth and space sciences and director of the Quaternary Research Center at the UW.
“West Antarctica is a very different place than East Antarctica, and there is a physical barrier, the Transantarctic Mountains, that separates the two,” said Steig, lead author of a paper documenting the warming published in the January 22 edition of the journal Nature.
The West Antarctic Ice Sheet, with an average elevation of about 6,000 feet above sea level, is substantially lower than East Antarctica, which has an average elevation of more than 10,000 feet. While the entire continent is essentially a desert, West Antarctica is subject to relatively warm, moist storms and receives much greater snowfall than East Antarctica.
The study found that warming in West Antarctica exceeded one-tenth of a degree Celsius per decade for the last 50 years and more than offset the cooling in East Antarctica. The NASA illustration above depicts the warming areas in red, with the dark red showing the area that has warmed the most.
This NASA/JPL image from space on the right shows that giant, snow-covered swaths of Antarctica melted in January 2005.
The researchers determined the temperature changes by devising a statistical technique that uses data from satellites and from Antarctic weather stations to make a new estimate of temperature trends.
“The thing you hear all the time is that Antarctica is cooling and that’s not the case,” Steig said. “If anything it’s the reverse, but it’s more complex than that. Antarctica isn’t warming at the same rate everywhere, and while some areas have been cooling for a long time the evidence shows the continent as a whole is getting warmer.”
A major reason most of Antarctica was thought to be cooling is because of a hole in the Earth’s protective ozone layer that appears during the spring months in the Southern Hemisphere’s polar region. Steig noted that it is well established that the ozone hole has contributed to cooling in East Antarctica.
“However, it seems to have been assumed that the ozone hole was affecting the entire continent when there wasn’t any evidence to support that idea, or even any theory to support it,” he said.
“In any case, efforts to repair the ozone layer eventually will begin taking effect and the hole could be eliminated by the middle of this century. If that happens, all of Antarctica could begin warming on a par with the rest of the world.”
Related National Geographic News story: Antarctica Heating Up, “Ignored” Satellite Data Shows