Arctic sea ice update – still happening before our eyes
Last month we noted that after momentarily being near the long-term average, Arctic sea ice extent had returned to tracking at very low levels for that time of year. The latest update from the National Snow and Ice Data Center makes clear that ice extent is remaining close to record low levels – but even more troubling is this graphic showing what’s happening with ice volume:
As the NSIDC notes:
Ice extent measurements provide a long-term view of the state of Arctic sea ice, but they only show the ice surface. Total ice volume is critical to the complete picture of sea ice decline.
The graphic above is based on modeling done at the University of Washington (info on the evidence supporting the model here).
The declining volume seems consistent with the idea that the Arctic ice cap is at risk through the loss of multi-year ice. Even when the ice extent seems to have recovered, such as it did in April, the fact that it is new and thin ice means it can disappear quickly. The NSIDC report tells us that:
… ice extent declined rapidly during the month of May. Much of the ice loss occurred in the Bering Sea and the Sea of Okhotsk, indicating that the ice in these areas was thin and susceptible to melt.
They note that it is too soon to know whether this year’s minimum Arctic sea ice extent, which is due in September, will be below the record low of 2007 – that will depend very much on weather conditions in the region over the next few months. But it seems likely that we’re headed for another minimum ice extent that will be considerably below average. And given that some experts are suggesting that the decline is happening at a faster rate for ice volume than for area, and well ahead of the predictions in the last IPCC report, there seems to be plenty of reason for concern.