Arctic sea ice has shrunk to its lowest extent on record, surpassing the previous record set in 2007 and surprising experts studying climate change, a US body says.
Satellite images show the ice cap melted back to 3.4 million square kilometres on 16 September - the minimum for the year and smallest extent on record, the National Snow and Ice Data Centre said.
Arctic sea ice expands and contracts seasonally, with the lowest extent usually occurring in September, AFP reports.
But this year's minimum came at the end of a summer that had already seen records for low extents of ice broken on 26 August and on 4 September.
Satellite records of the waxing and waning of the Arctic sea ice go back 33 years.