This is the worst kept secret in science as you have probably read about it in the past week in the news or earlier on this blog, but records for the arctic sea ice minimum extent were smashed this summer. The National Snow and Ice Data Center suggests that a minimum of 3.41 million square kilometers was reached on September 16, breaking the old record set on September 18, 2007 of 4.17 million square kilometers.
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| Source: NSIDC |
The image below provides a comparison of the sea ice extent on September 16 (white) with the median extent on that day from 1979–2000 and helps illustrate just how much sea-ice loss there has been during summer in recent years.
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| Source: NSIDC |
Many sea-ice extent records begin with the satellite record in 1979. Efforts have been made, however, to use proxy data to extend a sea ice record into the more distant past. For example, recent work by
Kinard et al. (2011) suggests that the recent decline may be unprecedented in at least the past 1,450 years (see red line, with 95% confidence interval indicated with shading).
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| Source: Kinnard et al. (2011) |
Perhaps we'll have a short-term rebound in the next year or two as happened after 2007, but in the long run, declines are expected to continue as a consequence of anthropogenic global warming. We will discuss possible implications of this sea-ice loss for weather in the midlatitudes in a future post.
The low amount sea ice is in part caused by the warm AMO cycle and the occurrence of a big arctic storm that broke apart the ice, furthering the decline in arctic sea ice. Meanwhile the antarctic sea ice is growing and setting records for coverage. Ocean cycles rule the weather.
ReplyDelete^^^Ding ding ding. Antarctic ice coverage is smashing records...but we won't mention that because it doesn't fit the narrative.
ReplyDeleteThe regional geography, climate, and cryospheric conditions of the Arctic and Antarctic are markedly different, and the more rapid warming and greater vulnerability of Arctic ice has long been anticipated. This is discussed, for example, at http://nsidc.org/arcticseaicenews/2010/07/rapid-ice-loss-continues-through-june/ and references therein.
ReplyDeleteWhen the Atlantic Ocean flips back to the cold phase, the ice will return, this has nothing to do with AGW.
ReplyDelete