The thin ice of modern life

(pinched from Peak Energy)

Scientific American has a post on the decline of arctic sea ice - Total Arctic sea ice at record low in 2010: study.

The minimum summertime volume of Arctic sea ice fell to a record low last year, researchers said in a study to be published shortly, suggesting that thinning of the ice had outweighed a recovery in area The study estimated that last year broke the previous, 2007 record for the minimum volume of ice, which is calculated from a combination of sea ice area and thickness.

The research adds to a picture of rapid climate change at the top of the world that could see the Arctic Ocean ice-free within decades, spurring new oil exploration opportunities but possibly also disrupted weather patterns far afield and a faster rise in sea levels.

The authors developed a model predicting thickness across the Arctic Ocean based on actual observations of winds, air and ocean temperatures. "The real worrisome fact is downward trend over the last 32 years," said Axel Schweiger, lead author of the paper, referring to a satellite record of changes in the Arctic.

"The real worrisome fact is downward trend over the last 32 years," said Axel Schweiger, lead author of the paper, referring to a satellite record of changes in the Arctic. 

The researchers at the University of Washington in Seattle checked the model results against real readings of ice thickness using limited submarine and satellite data.

The approach has some detractors because it is focused is on modeling rather than direct observations of thickness, and therefore contains some uncertainty.

Sea ice area is easier to measure by satellite than ice thickness, and so has not needed a modeling approach.

The figure above is from the Arctic Sea Ice Blog and shows [modelled] sea ice volume. The figure below (from The Cryosphere Today) shows the sea ice extent in millions of square kilometers.

The anomaly for this time of year is a loss of about 1.8 million square kilometers. What does that mean?

The maximum total sea ice area in winter is about 13 - 14 million square kilometers (also falling) or about 2 Australias. So the deficit in area at the end of the summer melt compared to the long term average is equivalent to 1 Queensland, 2 NSWs, 7 New Zealands or 20 Tasmanias.

Tassie often goes missing in stylised maps of Australia, but I think people might notice if Queensland did.