The seven lowest maximum Arctic sea ice extent measurements have all taken place in the last seven years, and 2011 is no different, according to the most recent satellite measurements taken by scientists at the University of Colorado Boulder’s National Snow and Ice Data Center.
“I’m not surprised by the new data because we’ve seen a downward trend in winter sea ice extent for some time now,” said CU-Boulder Research Scientist Walt Meier of the National Snow and Ice Data Center, who participated the latest study.
While the finalised measurements won’t be released until early April which will arrive with a full analysis of the winter ice growth season, current measurements say that the lowest annual maximum ice extent occurred on March 7, and came in at 5,650,000 square miles (9,092,793.6 square kilometres).
This maximum ice extent – the farthest point in the year at which the sea ice extends from the main Arctic ice sheet – is 463,000 square miles (745,126 square kilometres) below the 1979 to 2000 average, and equates to an area slightly larger than the states of Texas and California, combined.
“I think one of the reasons the Arctic sea ice maximum extent is declining is that the autumn ice growth is delayed by warmer temperatures and the ice extent is not able to ‘catch up’ through the winter,” said Meier. “In addition, the clock runs out on the annual ice growth season as temperatures start to rise along with the sun during the spring months.”
The maximum Arctic sea ice extent, on average, happens on March 6, but as early as February 18 and as late as March 31. The 2011 measurements are currently tied with those from 2006 for the lowest maximum sea ice extents measured since recordings begun in 1979.