Nunatsiaq Online
NEWS: Climate Change April 05, 2012 - 9:28 am

Arctic sea ice extent below average in March: data center

2012's sea ice stayed around longer, but it's likely to melt quickly

NUNATSIAQ NEWS
Arctic sea ice extent in March 2012 averaged 15.21 million square kilometres. The magenta line shows the 1979 to 2000 median extent for that month. The black cross indicates the geographic North Pole. (IMAGE COURTESY OF THE NSIDC)
Arctic sea ice extent in March 2012 averaged 15.21 million square kilometres. The magenta line shows the 1979 to 2000 median extent for that month. The black cross indicates the geographic North Pole. (IMAGE COURTESY OF THE NSIDC)

You may not be able to note the changes when you look out the window and still see frozen sea ice, but Arctic sea ice has already entered the spring melt season.

Arctic sea ice reached its annual maximum extent on March 18, says the Colorado-based National Snow and Ice Data Center, which uses satellite data to see how much of the Arctic Ocean sea ice covers.

Now the sea ice has started to shrink.

And while sea ice extent for March as a whole was higher than in recent years, it still came in below average, the NSIDC said in an April 4 update on sea ice conditions in the Arctic.

Arctic sea ice extent this March ranked in the bottom ten recorded over the past 34 years of satellite data, coming in ninth lowest.

Over that 34-year period, the day of the maximum sea ice extent has varied by more than six weeks, occurring as early as mid-February and as late as the end of March.

However, even with so much variability, the NSIDC says there is a “small trend” towards maximum sea ice extents occurring later.

This year’s maximum sea ice extent continued that trend, occurring on March 18, 12 days later than average, the NSIDC said.

It’s not clear why the maximum sea ice extent would happen later, given that, in general, Arctic sea ice extent is decreasing, it noted.

One possibility is that the lower winter sea ice extents might make it easier for ice to continue growing later in the season, or that a late cold snap or northerly winds could spread ice southward over parts of the ocean that would normally be ice-covered at that point.

But the new sea ice growth is very thin and likely to melt quickly, the NSIDC said.

That’s because sea ice age data shows that winter sea ice continues to be dominated by younger and thinner sea ice.

So, researchers do not expect the late maximum sea ice extent to strongly influence summer melt.

“The ice that grew late this winter is quite thin, and will melt rapidly as the sun rises higher in the sky and the air and water get warmer,” the NSIDC said.

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