Arctic sea ice reaches lowest extent ever recorded 28th August 2012 Arctic sea ice has melted to the lowest extent since satellites began measuring it, according to the National Snow and Ice Data Center.
On 26th August, the area of Arctic Ocean covered by sea ice fell to 1.58 million sq mi, or 4.10 million sq km. This number is 27,000 sq mi, or 70,000 sq km below the record low previously observed on 18th September 2007. Furthermore, the summer ice minimum does not usually occur until the melt season ends in mid- to late September, so the ice cover is expected to continue dwindling for the next two or three weeks. The ice cap naturally grows during the cold Arctic winters and shrinks when temperatures climb in the spring and summer. But over the last few decades, satellites have observed a 13 percent decline per decade in the minimum summer ice extent. Volume and thickness of sea ice has also continued to decline.
On 18th September 2007, the minimum extent of Arctic sea ice shattered all records. Compared to the long-term average from 1979 to 2000, it was lower by 1m square miles - the size of Alaska and Texas combined, or 10 United Kingdoms. While a large Arctic storm in early August appears to have broken up some of the 2012 sea ice and helped it to melt more quickly, the decline seen in recent years is far outside the range of natural climate variability. Scientists assert that the shrinking Arctic sea ice is linked directly to warming temperatures caused by an exponential increase in man-made greenhouse gases pumped into Earth's atmosphere. Arctic sea ice is vital to keeping the polar region cold and helping moderate global climate - some have dubbed it "Earth's air conditioner." The bright surface of Arctic sea ice reflects up to 80 percent of the sunlight back into space. However, the rapidly increasing area of dark open ocean has created a positive feedback effect, causing the ocean to heat up and accelerate the melting. This could, in turn, cause seabed permafrost to melt, releasing large amounts of methane - a greenhouse gas that is 25 times more powerful than CO2 in terms of its heat-trapping effects. An additional side effect of the ice melting will be the opening up of new areas to ships for oil exploration. On current trends, the Arctic is likely to be ice-free for at least one day per year by 2016, ice-free during the entire month of September by 2035, and ice-free for three months every year by the mid-2050s.
Comments »
|
