The winter of 2009-2010 was one for the record books across much of the U.S. Snow cover and cold temperatures settled in for much longer periods than normal across much of the southern and mid-Atlantic states. While “Climategate” consumed the media coverage and the president flew to Copenhagen in search of a climate change treaty, folks in Washington were snowed in for days at a time. When political will is needed to address global warming, it’s a tough sell to a guy who just spent three hours digging his car out of a snow drift.
But amid the howling winds and pontificating pundits, an oft-ignored subject in the media is that the frigid temps were not globally expressed. Sure Australia was dealing with record heat, but it’s always hot there in the summer (our winter). The bigger story was that this past winter that so brutally bore down on the southern US was actually pretty darn mild in the northern US and much of Canada. For example, Minneapolis had no snow at all in March, the first time that’s happened since 1898.
I think we often assume that if it’s cold where we are it must be even colder the farther north you go. In the northern hemisphere that’s generally true, but it’s not absolute. Plus it doesn’t have to actually be warmer in Duluth than it is in Charleston for the former to have a mild winter while the latter has a cold one. These assumptions can color our general understanding of global warming. It’s still ridiculously cold in the Arctic for most of the year, the problem is how much of that year flirts with and exceeds the magical melting point of water. That’s what determines the literal sea changes.
So I was wondering how the ol’ Arctic sea ice is faring this summer, now that we’re smack dab in the middle of it. I did a Google search on “sea ice extent” and found some data from the National Snow and Ice Data Center at the University of Colorado. There’s a lot of neat information presented at the site, and I was able to get that snapshot of 2010 Arctic sea ice pretty easily:
Although sea ice extent began in April 2010 well within the range of “normal” variation as compiled from 1979–2000, by May it had dipped into the realm of significant loss. By late June, we apparently set a new record for the lowest Arctic sea ice extent ever measured for that date, but by mid-July we were back within 2006–2007 levels. So 2010 looks like it might not set a record for the lowest sea ice extent over the entire summer (set in 2007), but it’s certainly on track to be yet another summer with significantly less ice than the 1979–2000 average.