George Monbiot, the long time investigator, reporter, activist, starts out with the bad, and gets worse.
I’m going to start with some bad news, and the bad news is this. Two degrees is no longer the target. And the news is contained in a recent paper written by James Hansen of NASA in the Philosophical Transactions of the Royal Society(1). And what Hansen shows is that the profoundly pessimistic assumptions in the latest IPCC Report are insufficiently pessimistic.
And the reason for this is as follows. The IPCC assumes that the melting of the ice sheets at the poles will take place in a gradual and linear fashion. And Hansen’s own work with the paleontological record shows that that is an “entirely implausible” (to use his term) scenario.
The last time we had two degrees of warming in the Pliocene 55 million years ago, the ice sheets at the poles did not melt – as the IPCC proposes – over a millennia, but within the course of one century. And they did not cause a maximum sea level rise within the course of one century – as predicted by the IPCC – of 59 centimeters, but of 25 meters.
And Hansen proposes that through a series of factors – the collapse of the buttresses that prevent the ice from sliding into the sea, the melt water trickling down through crevasses and lubricating the base of the ice sheets, and melt water on the surface of the ice sheets changing the albedo, making the ice darker and therefore absorbing more heat, will lead to the sudden and – certainly in geological terms – almost immediate collapse of both the West Antarctic and Greenland ice sheets within the course of one a century at somewhat less than two degrees of warming.
Monbiot has written lots about lots. For more, particularly about Global Warming, here and here. If you have the stomach for it, see this sad exchange with the once trustworthy Alexander Cockburn.
For one couple’s response to the grim prognosis see DJ at www.asymptoticlife.com