Sea ice, briefly

I doubt I’ll be running the ever-exciting competition again this year, due to a lack of people who strongly disagree with me (i.e., the decline will be on the long term-trend, plus some error margin).

But While I’m here there appears to be some excitement from Romm over a Grauniad study about a GRL study about the role of wind forcing in sea ice loss, in particular in 2007.

The paper says

The unprecedented retreat of first-year ice during summer 2007 was enhanced by strong poleward drift over the western Arctic induced by anomalously high sea-level pressure (SLP) over the Beaufort Sea that persisted throughout much of the summer. Comparison of the tracks of drifting buoys with monthly mean SLP charts shows a substantial Ekman drift. By means of linear regression analysis it is shown that Ekman drift during summer has played an important role in regulating annual minimum Arctic sea-ice extent in prior years as well.

which seems fair enough (I don’t guarantee it is true, but it looks like a perfectly reasonable thing to say). By the time this has reached the Grauniad the sub-headings have got a little dodgy Wind contributing to Arctic sea ice loss, study finds New research does not question climate change is also melting ice in the Arctic, but finds wind patterns explain steep decline but only a little bit dodgy. By sub-heading standards, this is pretty good (Romm says “especially misleading subhed” which looks over the top to me). Even the Daily Mail isn’t too bad.

For those not familair with the basic idea, sea ice either melts and grows in situ or is pushed about by the winds. Strong winds can either make it advance further than it “ought” to be able to get, or by pushing it too far south melt more of it than would be normal, or push it back north (see, I can’t even tell from the paper which one of those it is. Never mind, I don’t need to know). If you pinned your hopes on 2007 being the harbinger of a new trend, well, you’ve already been disappointed by 2008 and 2009 so this isn’t exactly a hammer blow. It just confirms the obvious: that there was something other than GW that made 2007 an exceptional minimum.

As Romm points out, we (well me, JA and Brian) still have $1000 between us on an ice-free Arctic by 2020, and oddly both sides still seem quite comfortable with that. Romm’s post links to an ice-volume “prediction” of zero by 2012-2016 which I think is absurd. But time will tell. 2012 certainly isn’t far off.