|Sea ice, Ross Sea, Antarctica, 1996. Photo © Bruce Luyendyk|
Recent news items have drawn attention to Antarctic sea ice, the floating ice a meter or so thick that forms from freezing of the oceans surrounding Antarctica. Sea ice coverage is seasonal, more in the austral winter (June-September) and less in the summer (December-March), a difference of six-fold. A way to think of the scale is that the maximum extent of the sea ice about doubles the area of ice (land and sea) at the bottom of our planet. The story is that a glitch has been discovered in the estimate of the rate of change (change year over year) in the area of sea ice around Antarctica1,2.
The result just discovered, is that the change revealed itself in a sudden increase, a jump, in sea ice area. The jump is an artifact of the data processing. The debate now underway is which method was correct; the method used before the jump or the method used after? It makes a difference in the rate of increase. If the original method was correct then the rate of increase is very small1, otherwise it is large. Regardless, the area is increasing at some soon to be agreed upon rate.