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Video: Arctic sea ice is in long term decline – so is it foolish to predict ice-free summers?

  • 08 Feb 2011, 12:57
  • Christian

The climate youtube site "Crock of the Week" had turned its attention to US ex-astronaut and climate sceptic Harrison Schmitt. Schmitt claims that environmentalists are modern-day communists and that Arctic sea ice is currently recovering.

The UK's home-grown climate sceptics have made similar claims - with respect to the sea ice at least.

Dr David Whitehouse, science editor of the climate sceptic thinktank The Global Warming Policy Foundation, argued in the Telegraph last April that the Arctic sea ice is not in decline, but is recovering:

 

"it does seem that the sea ice is returning to 'average' after the record lows of 2007 and 2008. There has been a definite recovery trend since then so far from being a progression towards ice free summers it seems that it was a temporary dip. The recent observations do make the 2007 projections that the region would be ice free by 2013 look very unrealistic. Given what is happening only the foolish would look many years into the future and predict ice free summers now."

In the video, the views of Rear Admiral David Titley, a US Navy meteorologist, chime with the scientific consensus that the Arctic sea ice is in long-term decline:

"we expect to see about four weeks of basically ice free conditions in the Arctic by the mid-to-late 2030's. By the middle of the century, we could be seeing quite easily two to three months of ice free conditions."

The National Snow and Ice Data Center - the US body that measures Arctic sea ice - writes in their FAQ, (last updated October 2009)

Sea ice extent normally varies from year to year, much like the weather changes from day to day. But just as one warm day in October does not negate a cooling trend toward winter, a slight annual gain in sea ice extent over a record low does not negate the long-term decline.

Like with temperature changes, scientists understand changes in Arctic sea ice on the basis of long-term trends, rather than short-term changes. The level fluctuates from year to year because of local weather and regional climate patterns so it is only by looking at the trend over several decades or more that the true pattern emerges. The NSIDC write:

Although the 2009 sea ice minimum was larger than the past two years, the rate of decline since 1979 increased to -11.2 percent per decade … sea ice in the Arctic is in decline in all months and the decline is greater and the rate faster than natural causes could account for.

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