Arctic sea ice reaches 5th lowest maximum

The extent of the Arctic sea ice has reached its maximum winter extent for the year, with the fifth lowest maximum area recorded since satellite observations began in 1979, the National Snow and Ice Data Center, or NSIDC, reported April 2. At 5.76 million square miles on March 21, the maximum area was consistent with a decline rate of 2.6 percent per decade, NSIDC said. The lowest maximum on record, observed in 2011, was 5.65 million square miles.

However, this winter has seen a distinctly larger amount of multiyear ice in the Arctic Ocean than was observed at the beginning of last winter. NSIDC attributes this increase in part to the survival of more first-year ice at the end of the summer than has been typical in recent years. In addition, the circulation of the multiyear ice pack in an ocean current known as the Beaufort Gyre and a reduced transportation of multiyear ice out of the Arctic through the Fran Strait both helped bolster the survival of multiyear ice in the Arctic Ocean, NSIDC says.

A pattern of surface winds associated with a change in the climatic conditions late in the winter freeze-up season caused a late-season surge in the ice extent, spreading out the ice pack in the Barents Sea and pushing the ice pack southwards in the Bering Sea. However, air temperatures remained unusually high throughout the Arctic in the second half of March, NSIDC says.

—Alan Bailey