Arctic sea ice extent, 14 September 2012. In 2012, sea ice in the Arctic shrunk to its smallest extent ever recorded, smashing the previous record minimum from 2007 and prompting warnings of accelerated climate change. guardian.co.uk

By John Vidal and Adam Vaughan, www.guardian.co.uk
14 September 2012 Sea ice in the Arctic has shrunk to its smallest extent ever recorded, smashing the previous record minimum and prompting warnings of accelerated climate change. Satellite images show that the rapid summer melt has reduced the area of frozen sea to less than 3.5 million square kilometres this week – less than half the area typically occupied four decades ago. Arctic sea ice cover has been shrinking since the 1970s when it averaged around 8m sq km a year, but such a dramatic collapse in ice cover in one year is highly unusual. A record low in 2007 of 4.17m sq km was broken on 27 August 2012; further melting has since amounted to more than 500,000 sq km. The record, which is based on a five-day average, is expected to be officially declared in the next few days by the National Snow and Ice Data Centre in Colorado. The NSIDC’s data shows the sea ice extent is bumping along the bottom, with a new low of 3.421m sq km on Tuesday, which rose very slightly to 3.429m sq km on Wednesday and 3.45m sq km on Thursday. Scientists predicted on Friday that the Arctic Ocean could be ice-free in summer months within 20 years, leading to possibly major climate impacts. “I am surprised. This is an indication that the Arctic sea ice cover is fundamentally changing. The trends all show less ice and thinner ice,” said Julienne Stroeve, a research scientist with the NSIDC. The shrinking of the ice cap was interpreted by environment groups as a signal of long-term global warming caused by man-made greenhouse gas emissions. A study published in July in the journal Environmental Research Letters, that compared model projections with observations, estimated that the radical decline in Arctic sea ice has been between 70-95% due to human activities. “We are on the edge of one of the most significant moments in environmental history as sea ice heads towards a new record low. The loss of sea ice will be devastating, raising global temperatures that will impact on our ability to grow food and causing extreme weather around the world,” said John Sauven, director of Greenpeace UK. Sea ice experts on Friday said they were surprised by the collapse because weather conditions were not especially conducive to a major melt this year. The ice is now believed to be much thinner than it used to be and easier to melt. […]

Arctic sea ice shrinks to smallest extent ever recorded