reposted | 28.08.2007 15:15 | Ecology
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
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.
Not only does this lead to the immediate affect of inundation of most of the
inhabited world - something like 60% of the people live within 50 Km of the
coast - it also means that you get a severe and sudden change in global
albedo change as white stuff at the poles gives way to dark stuff absorbing
much more solar radiation.
And he proposes that we can't go beyond 1.5 to 1.7 degrees of warming
above 1990 levels.
Combine this with what Richard was talking about and the stuff contained
in the IPCC's 4th Assessment Report which shows that in order to have a
maximum cap of two degrees of warming we need an 85% global reduction
even before you take population growth into account. So when that's added
to the fact that we're going to have something like a 50% increase in population,
you can see that that pushes way over 90% even before you take the issue
of global equity into account which means that the rich nationsmust cut the
emissions much further than anybody else, you realize that we are talking at
a minimum of a 100% cut, and it looks like it might have to go to 110% or 115%.
You laugh but we're talking about sequestration and we're talking about such
things for example, as growing bio fuel and burying it, simply for growing as
much bio mass as we can and sticking it back on the ground....something.....
anything to stave off this catastrophe.
We're not talking anymore about measures which require a little bit of tweaking
her and there, or a little bit of political tweaking here and there. We're talking
about measures which require global revolutionary change.
And that is a much tougher message than any that I've put out before, and this
is the first opportunity really that I've had since that paper came out, to express
the fact that what I thought were rather bold and revolutionary proposals in my
book "Heat", those proposals don't go nearly far enough. Those proposals
have been superseded and we need to start thinking on a different scale
And I'm afraid the second uncomfortable message I have to put out to you tonight
is that when it comes to dealing with a problem of this scale, small is no longer
beautiful. We have to start thinking on the biggest possible terms....
We have very very little time in which to act. We have very very little time in which
to bring about the largest economical and political transformation the world has
The entire speech along with other speakers can be listened to free online courtesy
of the UK IMC. Mr. Monbiot is the second speaker at 15 minutes in.
1) Dr. James Hansen's Paper, 7/15/07