New evidence on Arctic sea ice trends

Dana Nuccitelli in The Guardian reports, 20th October 2014: “The National Snow and Ice Data Center has reported that this year we saw the 6th-lowest minimum Arctic sea ice extent on record. Research has shown that most of the long-term decline in sea ice, or the “death spiral” as it’s come to be known, is due to human-caused global warming.

Natural factors play a role in the extent of the Arctic sea ice as well, especially changes in weather conditions on a year-to-year basis. For example, 2012 shattered the previous record low Arctic sea ice extent because on top of the human influences, the weather conditions were ripe for a dramatic decline that year. In 2013 and 2014, weather conditions were closer to normal, so they didn’t break the 2012 record. As a result, the usual suspects have declared that Arctic sea ice is now “expanded” compared to two years ago.

The flaw in that argument is illustrated in this animated graphic I created. We can also consider Arctic sea ice extent further back in time, over the past 145 years:

 Average July through September Arctic sea ice extent 1870–2008 from the University of Illinois (Walsh & Chapman 2001 updated to 2008) and observational data from NSIDC for 2009–2014.

Average July through September Arctic sea ice extent 1870–2008 from the University of Illinois (Walsh & Chapman 2001 updated to 2008) and observational data from NSIDC for 2009–2014.

Or even the past 1,450 years:

Reconstructed Arctic sea ice extent over the past 1,450 years, from Kinnard et al. (2011)

Reconstructed Arctic sea ice extent over the past 1,450 years, from Kinnard et al. (2011)

The current Arctic sea ice death spiral is clearly outside the norm and natural variability we’ve seen in recent history. Exactly how rapidly it will continue to decline is a subject of open debate among climate scientists.

Source: The Guardian, 20th October 2014. For full details see: http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/oct/20/2014-arctic-sea-ice-extent-6th-lowest-in-millennia

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