Thursday, 13 September 2007

Arctic Sea Ice Extent

I’ve finally gotten around to creating a blog, so I need to start it off somehow with a post, hopefully not a completely purile one. Since I obsess a bit about global warming and climate change I’ll start with a thrilling post about the Arctic sea ice extent.

If you didn’t know, the Arctic sea ice extent has alread
y broken the previous record of 5.32M Km2 set in 2005 by 1.08M Km2 - it’s now 4.24M Km2 and could easily fall for another 2 or 3 weeks (although it may stop any day now). It’s not just that it’s smaller than ever, but that it’s breaking records of all kinds:
  • It’s the largest single fall recorded for a single year.
  • Highest temperatures Recorded.
  • It’s the first time the Northwest Passage has opened.
  • It’s melted perennial sea ice the size of California (Ice that’s been around every day of every year since at least 1979).
  • Ocean warming itself is now contributing to ice melt.
The thing for me though is that most people are still predicting the Arctic ice caps will be free of ice in the summer by 2030, but simply looking at their graph makes it look like (at the current rate over 2005-2007) the ice caps will be free of ice by the summer of 2015. The calculation’s simple: 4.24M Km2 / 0.55M Km2/Yr => 8 years.

But how bogus is my guess? Well, I’m not a climate scientist, so probably very! But it’s worth noting that my estimate is based on a current rate of decline when it’s fairly obvious that the rate of decline is accelerating. Secondly, not only is the rate increasing, but it’s becoming more consistent. Year to year increases since 2001 haven’t exceeded 0.45M Km2 (average 0.26M Km2), which prior to 2001 averaged 0.68M Km2. Thirdly, there's a good reason to believe ice melt will increase and be more consistent - namely that the arctic ocean is playing a greater rôle, absorbing more summer heat, because the cap is shrinking. And the ocean will act as a massive heat exchange, preventing the cap from fully recovering in the winter, and by regulating heat release during the yar.

Scary isn’t it?