As the Antarctic Ice sheet approaches the point of no return for inevitable collapse, winter sea ice is increasing in the waters around the continent. This seems like a contradiction, but is it? The Antarctic ice sheet rests on the land mass, and rate of loss of the has tripled in the last 5 years–a worrying trend considering that 90 percent of the Earth’s ice is located there.
In contrast, the sea ice is floating on water and this floating ice has expanded even though Southern Ocean temperatures are increasing. The recent expansion is probably due to a combination of changing wind patterns and the cool, fresh melt water interacting with the ocean surrounding Antarctica. When the meltwater mixes with seawater, the result is less dense water that is closer to the freezing point. This forms a pool of surface water around the continent that can then more readily freeze onto the floating sea ice.
As the news release states, “as counterintuitive as expanding winter Antarctic sea ice may appear on a warming planet, it may actually be a manifestation of recent warming.”