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| Cambridge Professor and Arctic expert Peter Wadhams |
UPDATE 27 AUGUST: Sunday's data confirms that the previous sea-ice extent minimum of 24 September 2007 was broken last Friday, 24 August 2012. What is also stunning are sea-ice daily extent figures averaging ice loss of more than 100,000 square kilometres per day for the last four days. This suggest melt is accelerating very late in the melt season in a pattern that has never before been observed. The Arctic this year is heading into new territory and it looks like 2012 may in retrospect be seen as the year when a new melt regime took hold.Climate change impacts are frequently happening more quickly and at lower levels of global warming than scientists expected, even a decade or two ago. And this week the Arctic has provided a dramatic and deeply disturbing example.
The ice extent is about to drop below 4 million square kilometres for the first time in the satellite record, and the Arctic has shed almost half a million square kilometres of sea-ice in last five days! With three weeks of the melt season still to go, it's not hard to see extent dropping another half a million square kilometres (or more!) to 3.5 million square kilometres. (In previous big melt years of 2007 and 2011, around half a million square kilometres was lost after 26 August.)
This is starting to make the second graph (below) looking reasonable, and those scientists and models which have been suggesting an sea-ice-free summer Arctic within a decade to be on the money.
The commentary by Climate Commissioner Prof. Will Steffen in today's newspapers that ''We can expect to see an ice-free Arctic at about the middle of this century'' looks out of touch with the most recent data, and exhibits IMHO a scientific reticence which does a disservice to the urgent public debate we need on implications of the Arctic melt for Australian climate policy (and sea-level rises from Greenland!). Positive feedbacks now have a grip on Arctic sea-ice and the descent appears to be exponential, not linear. Looking at the PIOMASS date on sae ice volume (fifth chart here), its hard to know what Prof. Steffen has based his assertion upon.
Perhaps the enormity of the present situation is best summed up by sea-ice blogger Neven: "Basically, I'm at a loss for words, and not just because my jaw has dropped and won't go back up as long as I'm looking at the graphs. I'm also at a loss - and I have already said it a couple of times this year - because I just don't know what to expect any longer. I had a very steep learning curve in the past two years. We all did. But it feels as if everything I've learned has become obsolete. "
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| JAXA Arctic sea ice extent to 24 August 2012. Updates: http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm |
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| Projected sea-level rise to 2100 (inches). Source City of Boston |
Update to: Dramatic lessons from the Arctic big melt of 2012: It's already too hot, as Greenland melt record is smashedby David Spratt, first published at RenewEconomy, 21 August 2012
Related post: US Media Turn A Blind Eye To Record Greenland Ice Melt
Related post: Arctic heads for record melt, but do we want to know?
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| Cryosphere Today sea ice area August 2005-2012 |
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| Arctic sea-ice extent decade by decade: the rate of loss is increasing. Source: http://www.ijis.iarc.uaf.edu/seaice/extent/Sea_Ice_Extent.png |
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| Extensive melt over the Greenland Ice Sheet. This figure shows the daily, cumulative area of the Greenland ice sheet showing surface melt for 2012, 2011, 2010 and for the 1980 to 1999 mean. While melt was unusually extensive through May and June of 2012, the melt area increased rapidly in early July in response to an unusually warm weather event. Source: http://nsidc.org/arcticseaicenews/2010/08/a-most-interesting-arctic-summer/figure6-2/ |
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| Arctic sea-ice volume (red line is 2012) from https://sites.google.com/site/arctischepinguin/home/piomas |
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| Figure 1: Fire fighters battle the Taylor Creek blaze, one of several fires which have burned over 75,000 acres in southeastern Montana in summer 2012. Image credit: USFWS/Gerald Vickers via InciWeb.org. |
