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.