Scientists have thought a lot about this question.
Unlike the Arctic, Antarctica is surrounding by water, so its less responsive to changes in air temperatures. Its climate is more governed by wind and ocean currents. Paradoxically, the ozone hole also may play a role in keeping Antarctica cool, scientists say.
Interestingly, climate models have generally predicted that Antarctic sea ice wont change much in the coming decades, before eventually losing mass.
Only recently have scientists begun to understand why, in part due to research by Judith Curry among other. In a 2010 paper (see abstract) in Proceedings of the National Academy of Sciences, Curry said the answer is tied up in a combination of natural variability and global warming. (By the way, skeptics, before you dismiss Curry youd do well to understand that shes a harsh critic of the IPCC.)
Heres a deeper explanation of what she found, based upon an interview I conducted with her:
So give me a non-sound bite answer.
Sea ice can melt from both above and below, either heating from the ocean below or the atmosphere above. In the case of the Arctic most of the melting is driven from the warmer atmosphere above. In the Antarctic most of the melting has been driven from the ocean below. What our study has identified is that theres been increased precipitation over the last few decades that has freshened the upper ocean, which makes it more stable so the heat below doesnt make it up to the sea ice to melt it.
Freshens the upper ocean?
It decreases the saltiness. When you have a fresh layer on top thats less dense it acts as a barrier to prevent the mixing of warmer water from below. It insulates the ice to some extent. Weve also seen a big role of natural variability, over the past 30 years or so the dominant climate signal has been from the Antarctic Oscillation rather than from global warming. The net effect of all this has been an increase in precipitation, mostly snow. This diminishes the melting both from below and above. It stops the melting from above because snow has a higher albedo and reflects more sunlight.
At some point does this result in a net loss of ice rather than gains?
What happens in the 21st century projections is that the global warming signal begins to dominate. We still have the freshening of the upper ocean, but the upper ocean is getting warmer because of a warmer atmosphere. And the precipitation starts to fall more as rain than snow. Rain falling on ice speeds the melting from above.
The bottom line is that scientists generally have predicted that the Antarctic sea ice will not begin substantially melting until the second half of this century.
Does the expanding Antarctic sea ice disprove global warming? | SciGuy | a Chron.com blog