Mainly due to climate warming, the Arctic sea ice hit record low in January this year, the U.S. National Snow and Ice Data Center (NSIDC) said Tuesday.

Arctic ice in January covered 5.23 million square miles (13.55 million square km), 19,300 square miles (50,000 square km) less than the previous record in 2006, the NSIDC said in a report published on the website LiveScience.com.

The ice extent was the lowest since Arctic ice monitoring began in 1979.

According to the NSIDC, Arctic winter sea ice has declined by approximately 3.3 percent per decade since 1979.

This January's ice cover was also 490,000 square miles (1.27 million square km) below the 1979 to 2000 average, the report said.

This winter has been cold and snowy in North America, but farther north, temperatures have been unusually warm. Data collected by NASA's Aqua satellite show that ice was low in Canada's Hudson Bay, Hudson Strait and the Davis Strait between Canada and Greenland, according to the report.

Normally these areas are frozen over by late November, but this winter, they didn't freeze until mid-January 2011, the report said, adding that the Labrador Sea was also ice-free.

There were two possible explanations for the extended thaw, the report said.

The Arctic Oscillation, a seesaw pattern of atmospheric pressure differences, was in negative mode in December 2010 and January 2011. When the Arctic Oscillation is negative, it brings cold and snow to Europe and North America but allows warmer air to creep into the Arctic.

Another factor, said the NSIDC, could be that areas of open ocean were still releasing heat into the atmosphere. Bright white ice reflects solar heat back into space, but dark ocean waters (or those without ice cover) absorb the energy, warming and reinforcing the ice-melting process.

The National Oceanic and Atmospheric Administration (NOAA) has forecast that the Arctic Oscillation should return to positive mode in February 2011, according to LiveScience.com.