The National Snow and Ice Data Center reported Monday that in the first 10 days of August, Arctic sea ice extent declined one million kilometers. Sea ice is now disappearing on a daily basis nearly 50% faster than it typically does this time of year.
So the race is on again to see whether 2008 can repeat — or beat — the record set only last year. The NSIDC explains exactly what is going on in the Arctic this summer:
Ice extent has begun to decline sharply. The decline rate surged to -113,000 square kilometers per day on August 7 and as of August 10 was -103,000 square kilometers per day. This compares to the long-term average decline of -76,000 square kilometers per day for this time of year. Normally, the peak decline rate is in early July.
Many of the areas now seeing a rapid retreat saw an early melt onset (see July 2, 2008); this helped set the stage for rapid retreat (July 17 and April 7). However, the more fundamental issue is that these regions started the melt season covered with thin first-year ice, which is especially vulnerable to melting out completely. Thin ice is also vulnerable to breakup by winds; the last ten days have seen a windy, stormy pattern that has accelerated the ice loss.
I’m still happy to take bets on ice-free Arctic by 2020 — more than half a century earlier than virtually every model has been predicting (see “Another big climate bet — Of Ice and Men“).
[h/t to Johnny Rook’s Climaticide Chronicles]