Tuesday, September 04, 2007

Arctic sea ice continues to set records

Traveling from the tropics back to the poles:

The extent of sea ice in the Arctic continues set records. This map from the National Snow and Ice Data Center from Sept 3rd shows the sea ice at 4.42 million square kilometers, already far below the lowest recorded value of 5.32 million square kilometers from Sept 20-21, 2005. The pink line on the map is the median extent.

Just incredible. If you're looking for just one sign of dramatic climate change, one that follows from our basic understanding of the climate system and the exchange of heat between the planet's surface and the atmosphere, and one that may be out-pacing all of our predictions, skip all the complicated questions about hurricane frequency and intensity, and look at the precipitous drop in the extent of Arctic sea ice. May the flag planting continue...


Unknown said...

I'm rubbish at this blogging lark, but you might enjoy the numbers game & the graph here: http://fergusbrown.wordpress.com/2007/09/05/the-future-for-huskies/

I am sure you could have done a better job.

Simon Donner said...

Fine point (sarcasm? honesty? frustration?). There's been a slight upward Antarctic trend over the same time period.

My understanding is the polar amplification of warming should be greater in Arctic - all ocean, so if you melt or thin some ice, more radiation can penetrate to the dark water, less is radiated back to space. Of course this is coming from someone who studied lake ice not polar ice.

There's also the issue of the Arctic Oscillation and how much of a role the decadal variability in ocean circulation and atmospheric pressure / upper level flow is influencing sea ice extent. The recent papers on the Arctic seem to be showing that, like what we found for tropical north Atlantic and Caribbean sea surface temperatures, the anthropogenic "signal" is emerging from the background variability.