Arctic sea ice may have started its annual fall refreezing after reaching an all-time record low, according to the National Snow and Ice Data Center.
Arctic ice now covers 1.61 million square miles, the agency said Thursday, up from 1.59 million on Sept. 16, which appears to be this year's annual minimum, when sea ice is at its lowest.
Following its annual summer thaw, sea ice in the Arctic typically reaches its yearly minimum in mid-September. Its yearly maximum is usually in March.
Some variability could still occur this year, however, the agency cautioned.
The previous record low for Arctic sea ice was 2.05 million square miles set on Sept. 20-21, 2005, and the average low at the end of the summer melt is 2.60 million square miles.
The Northwest Passage between the Atlantic and Pacific oceans along the coasts of Canada and Alaska remains open but it starting to refreeze, the center said. The Northeast Passage along the coast of Siberia is closed by ice, according to the center, located in Boulder, Colo.