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Sep. 6th, 2007
arctic sea ice update
Sep. 6th, 2007 02:25 pmArctic sea ice area seems to have levelled off, at about 3 million square kilometres (60% of the long-term average for early September). Sea ice extent is still dropping: 4.42 million square kilometres on 3rd September (also about 60% of average). So mean ice concentration has returned to a fairly normal level, over the part of the arctic which still has any ice!
This is the Arctic basin. To the best of our scientific knowledge, this area has been covered in dense ice pack continuously for many thousands of years. The ice pack drifts around with winds and currents, and melts around the edges in the summer. The older multi-year ice gradually drains out of the arctic basin (generally down the east coast of Greenland) to be replaced by younger ice.
In an average melt season, the edges of the ice pack melt and thin: the central pack remains close to 100% ice but gaps open up around the edges such that over the whole extent only 70% is ice by the end of the season.
This year that central pack is all that remains, and is only 70% ice.
The melt season continues. This close to the equinox, it would be nearly over in an average year (the arctic sun is very low now, and will set soon). This is not an average year: the much lower ice area and lower cloud cover through the summer means that the sea and air are much warmer than normal (I've seen the number +7C on one web site, which I pray is wrong).
Daily PNGs of ice concentration are here. Raw data are in a nearby directory; I haven't got around to writing the code to process it. The data set description is here.
This is the Arctic basin. To the best of our scientific knowledge, this area has been covered in dense ice pack continuously for many thousands of years. The ice pack drifts around with winds and currents, and melts around the edges in the summer. The older multi-year ice gradually drains out of the arctic basin (generally down the east coast of Greenland) to be replaced by younger ice.
In an average melt season, the edges of the ice pack melt and thin: the central pack remains close to 100% ice but gaps open up around the edges such that over the whole extent only 70% is ice by the end of the season.
This year that central pack is all that remains, and is only 70% ice.
The melt season continues. This close to the equinox, it would be nearly over in an average year (the arctic sun is very low now, and will set soon). This is not an average year: the much lower ice area and lower cloud cover through the summer means that the sea and air are much warmer than normal (I've seen the number +7C on one web site, which I pray is wrong).
Daily PNGs of ice concentration are here. Raw data are in a nearby directory; I haven't got around to writing the code to process it. The data set description is here.