Regular readers will know that I’ve been keeping a close eye on this year’s Arctic summer, and the record minimum sea ice extent reached last month (nice NASA picture here). The ice area is increasing now, but is still about 1m km2 below the same time last year. I might have to increase my bet… If all the summer Arctic sea ice disappears quickly, it won’t have any impact on sea level, but if the ice on land – mountain glaciers and the great ice sheets of Greenland and the Antarctic – melts, sea level will rise. During the last interglacial, about 125,000 years ago, global temperature was a degree or two warmer than today and sea level was about 5m higher. Some of that extra water came from Greenland and Antarctica.
When I was writing Hot Topic, the latest information suggested that Greenland was losing about 200 km3 (cubic kilometres) of ice every year, and Antarctica about 150 km3 (HT, p45). But time goes on, and the world warms. A study to be published in Geophysical Research Letters suggests that the glaciers of southeast Greenland are now losing 300 km3 of ice per year, a 400% increase in melt rate since 2004. AFP reports:
“Until 2004, the glacier mass in the southeastern part of the island lost about 50 to 100 cubic kilometres (12 to 24 cubic miles) per year. After this date, the melting rate accelerated to 300 cubic kilometres per year. It’s a jump of 400 percent, which is very worrying,†National Space Center head researcher and project chief Abbas Khan told AFP. […] The measurements indicated that the mountains hugging glaciers in the southeastern part of Greenland rose four to five centimetres (1.5 to two inches) per year, and that the banks of the glaciers thinned 100 metres per year.
