Now you sea ice, now you don’t

Last night I attended a talk about Arctic sea ice by Mark Serreze from the National Snow and Ice Data Center in Colorado. There are a few interesting items I can relate. First, within the next couple weeks we’ll hit the summer minimum of area covered by sea ice in the Arctic. We’re on track to possibly break the record for sea ice extent (it will be close) which was set in 2007.

Sea ice has been melting very rapidly– constantly exceeding predictions– and Mark is confident that we will see an Arctic ocean that is completely ice free in summer in 20 to 30 years. A lot of people are trying to figure just why it’s melting so fast, but we haven’t quite figured it out yet. Take a look at how climate models used in the last IPCC report projected sea ice (light colored lines- black line is the average) compared to what’s actually been going on (red line).

Melting sea brings up a whole range of political issues- who will control shipping routes through the Arctic? Who will lay claim to the oil and gas reserves that will become available for drilling? Mark said the military is very interested in this. As one naval officer told him, “All I know is that there’s more blue water up there that I have to patrol.”

Besides those issues, Arctic sea ice loss is a pretty big deal climate-wise. When white sea ice is replaced by dark, open ocean, much more solar radiation is absorbed, heating up the sea surface (and the atmosphere above it) which, of course, causes more sea ice melting, and on it goes. The Arctic is the region of the world most susceptible to warming. Unfortunately for the rest of the world, one of the things that will happen as the Arctic warms is that the permafrost will thaw, releasing a massive amount of methane (a very potent greenhouse gas) to the atmosphere, and on it goes.

That thawing permafrost couldn’t be simulated with the models that went into the last IPCC report, adding another reason why the warming projections were likely too low. For the next IPCC report (which should be out in a couple years), many model projections will be able to simulate this feedback.

For a host of reasons, Arctic sea ice is something to keep a close eye on.


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