|2010-12-01 09:20:49||Tipping point reached in the Arctic|
I know there was a great post recently on an ice-free Arctic, but I got an email the other day from Mike Serreze at the NSIDC:Steve
We are on track to see an ice-free (or nearly so) Arctic Ocean at summer’s end in the next several decades, possibly early as 2030. The decline in ice extent will not be smooth – due to year-to-year variability in weather patterns, we will see temporary rises in summer extent, superposed on the overall downward trend. For example, following the record low extent in September 2007, we saw some recovery in September of 2008 and 2009, but then a plunge in 2010. It appears that the overall downward trend in September ice extent is now accelerating. The available evidence points to several mutually supporting processes. The sea ice cover in spring, at the onset of the melt season, is thinner than it used to be, such that large areas of the pack ice are increasingly likely to melt out in summer, exposing areas of dark open water that readily absorb the sun’s energy, melting out even more ice, leading to even thinner ice the following spring. At the same time, with thinner ice in spring, weather patterns known to favor summer melt now have a greater effect on the ice cover. For example, had the same melt-favoring weather pattern that we saw in summer 2007 occurred 30 years ago when the ice was thicker, it would not have had nearly the same effect on the ice cover. The ice could take a punch back then. Now it cannot. Finally, as the Arctic continues to warm up, it becomes less and less likely that we’ll see a series of cold summers that could bring about recovery. If we view a “tipping point” simply as a point of no return, in that an ice-free Arctic Ocean at end of summer is now inevitable, I’d say that the evidence is strong that we have crossed it.
Mark C. Serreze
Do we think this may form the basis of a new post?
Yes, this would be interesting. What I have read in various places suggests that Extent is on a downward slide, but so to is Total Mass. And Researchers up there have been reporting that the multi-year ice that is the backbone of maintaining year to year levels is growing weaker - reports of patches in the MY ice that are open holes covered with 1st year ice - more NY ice that is dangerous to walk on and easier than usual for ice-breakers to get through
My group do a fair bit of Arctic stuff, I'll try and speak to some of them.
A Professor I know thinks there is good evidence that part of it is to do with wind patterns which could easily be natural variability. I'll ask about papers; it's good to see the whole picture!