We haven’t heard a lot about the other ice sheet, the one at the South Pole. This is probably because no one lives on in the Antarctic, other than a few very cold scientists, and not that much is known about it, compared to the arctic, where data was amassed by Canadian, United States, and the Soviet military in their struggle for power during the cold war. What we do know is that the Arctic is in a very bad state: September Arctic sea ice has decreased between 1973 and 2007 at a rate of about -10% +/- 0.3% per decade. By contrast, ice in the Antarctic has shown very little trend over the same period, or even a slight increase since 1979.
So what’s going on? The short answer is that we’re not quite sure. What we do know is the Antarctic sea ice is a volatile beast, growing during the winter months to an area twice the size of Europe, and shrinking during the summer to one sixth of it’s winter area. This means long term trends are pretty difficult to measure, especially because most of the data only goes back 30 years or so. In contrast, Arctic ice is more stable, so long term trends are easier to monitor. Antarctic sea ice is also susceptible to El Niño and La Niña, the ocean current systems that scientists say are responsible for the particularly cold winter we are having this year. There has also been more snow at the Antarctic and there’s a possibility that this snow is becoming ice and slowing down the rate of melt at the South Pole. Then there are the errors in our climate models because any model will have to make simplifications and assumptions, and predicting as complex system as the environment is fraught with difficulties. Arctic ice is melting much faster than the models predicted, says Stephen Ackley, a polar scientist at the University of Texas, San Antonio, in an interview to the Christian Science Monitor. By contrast, “Antarctic sea ice is well behind what the models project.”