The volume of sea ice in the Arctic hit a new low this past winter, according to observations from the European Space Agency’s (Esa) Cryosat mission.
During March/April – the time of year when marine floes are at their thickest – the radar spacecraft recorded just under 15,000 cu km of ice.
In its three years of full operations, Cryosat has witnessed a continuing shrinkage of winter ice volume.
It underlines, say scientists, the long-term decline of the floes.
Thirty years ago, there were perhaps 30,000 cu km at the height of winter.
While there has been a great deal of attention focused of late on the falling extent (area) of sea ice in the Arctic, especially during summer months, researchers emphasise that it is volume that provides the most reliable assessment of the changes now underway in the northern polar region.
“In terms of really understanding what is going on in the Arctic and trying to put the changes we see in the larger scale context – volume is the key part of the story,” explained Prof Alan O’Neill, chairman of Esa’s Earth Science Advisory Committee.
“What Cryosat has done in the past three years is to confirm the volume decline predicted by the modelling from the atmospheric record.
“The $64,000 question is what’s causing this decline? It’s certainly consistent with what we expect from global warming, but we also need to understand better the natural variation that occurs in the system on perhaps decadal timescales. Cryosat can begin to help us do that as well.”
Source: Jonathan Amos | BBC News