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Arctic sea ice extent reaches new low in satellite history

  • 29 Aug 2012, 11:30
  • Carbon Brief staff

Last week, a number of institutions announced that sea ice in the Arctic had reached its lowest since satellite records began in 1979. The Danish Meteorological Institute, the Japan Aerospace Exploration Agency and the Norwegian Arctic ROOS all announced that according to their measurements, a record low had been reached.

These records had by and large failed to make the news until the prominent US research group the National Snow and Ice Data Centre (NSIDC) reported on Monday that daily extent is now the lowest in the satellite era. It says:

"Arctic sea ice extent fell to 4.10 million square kilometers (1.58 million square miles) on August 26, 2012. This was 70,000 square kilometers (27,000 square miles) below the September 18, 2007 daily extent of 4.17 million square kilometers (1.61 million square miles)."

Since it measures sea ice minimum extent over the course of the month, NSIDC says its announcement isn't yet official. But that didn't stop almost every major media outlet from reporting the figures.

The media covers it

To find out what the new record low might mean for climate change, most outlets asked scientists.

Weather in the region affects how the ice melts. Both The Independent and The Guardian, quoting Mark Serreze at NSIDC, report that beyond an early storm in August, weather patterns this summer have not been out of the ordinary, but after many years of warming "the ice is so thin and weak now, it doesn't matter how the winds blow."

Newer ice that is only one winter old is much thinner than ice that has been present for many years. Speaking to research scientists at NASA, The BBC explains that numerous warm years have reduced the amount of multi-year ice cover, leaving summer ice thinner and vulnerable to break up. This effect means that it's more likely that the ice will reach record lows, even without the poor weather conditions experienced in 2007 when the previous record was set.

While all coverage made the link to climate change in some way, The Telegraph reported scientist Michael Mann from Penn State University saying that these changes are happening faster than climate models predicted. Meanwhile, modelling that assesses sea ice volume suggests that 2012 has also seen a new low over the same timescale.

Asking scientists

There are dissenting voices - notably from the same small group of scientists who usually disagree with the scientific community on climate. The Sunday Times argues that "some scientists are being more cautious" about interpreting these figures. Citing John Christy from the University of Alabama, who suggests that the climate is not particularly sensitive to carbon dioxide, the article says that anecdotal evidence proves similar warming periods have occurred and that its difficult to separate climate change and natural variability.

The Washington Post cites Patrick Michaels of US thinktank the Cato Institute, who argues: "The overall loss in sea ice from the planet is less than people often assume," and claims that sea ice has been expanding at the South Pole. But other climate skeptics have suggested such arguments are weak.

Watts Up With That attributes the record low to the early August storm, and claims that NSIDC's data-gathering method is old and unreliable. Walt Meier from the NSIDC responds to these claims in comments, explaining why the satellite monitoring system used is the best for identifying year-to-year variations.

With all this interest, expect to see more coverage, particularly when NSIDC announce that the sea ice has reached its minimum extent - some time in the next few weeks. In the Washington Post, meanwhile, Brad Plumer has produced an eight point list on why he thinks the new record melt matters.

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