The sea ice in the Arctic Ocean is late to reach its yearly minimum. Daily satellite measurements show that after a small recovery with some net expanding, melting continued through the second half of September. Usually around this time of the year the temperature drops sufficiently to halt the decline and slowly work towards the winter maximum in sea ice extent.
Both the summer minimum and the winter maximum have shown a dramatic and continued trend of melting, ever since satellites started to contribute the needed data, in the late seventies of the 20th century.
The ‘all-time’ low happened in the year 2007. On September 16 the total extent of sea ice was a staggering 39 percent less than ‘normal’ – pointing out a fatal path for the Arctic ecosystem, with its great importance as a solar reflector and a net carbon sink for many thousands, possibly millions of years. It may have been that warning signal that prompted the world to reach some sort of breakthrough a couple of months later, when UN climate negotiations on Bali agreed to succeed in Copenhagen and to curb global through an ambitious new climate treaty – only to fail two years later, December 2009, in the very Danish capital, during the final conference.
So has the Arctic warning signal expired? The year 2007 beat the previous record of 2005 – when the sea ice extent dropped to 23 percent below average. Back then the 2005 September minimum was a genuine shock to the scientific community and much beyond.
This year little attention is being paid to the fact that sea ice extent is again well below the ‘old’ 2005 record: 0.7 million square kilometers of ice less, to be precise. June 2010 even crossed the line of June 2007. It did not exactly reach the headlines.
By now we write September 25 and NSIDC has still not confirmed the yearly minimum. We are well below September 2005, and counting. We are at present a little above the 2007 record. But however damaging that year may have been, by this date the Arctic was forming ice again. This year, it’s Indian Summer up North.
(c) Rolf Schuttenhelm | www.bitsofscience.org