Today, a group of the 'world's top climate scientists' came to Bali to call for deep emission cuts. 'Time is running out,' one of them warned, 'Humanity cannot afford a failure at Bali.'
Stirring stuff. But, in many ways, their statement was most notable not for who signed it, but for which climate scientists refused to, and why. And for what it left unsaid, as much as what it did tell us.
But first, the demands the scientists made. It's a familiar list:
- Keep temperature rises below 2 degrees.
- Ensure global emissions peak in the next ten or fifteen years.
- Drive them down by at least half of 1990 levels by 2050.
Many governments - and, in theory at least, all those in the Kyoto club - are signed up to these goals. They too read the IPCC report on which today's science declaration relies. So what did the statement add?
My attention was piqued, however, by a quote from Andrew Pitman on the press materials we were given:
[quote]If we can stabilize greenhouse gases at below 450 parts per million equivalent, we mayprevent dangerous climate change.[/quote]
I asked Professor Pitman what that word 'may' meant. His answer was, on current evidence, stabilization at 450 ppm gives us a 50/50 chance of avoiding a 2 degree temperature rise. Not great odds, one might think. Get levels down to 400 ppm and the chances rise a bit, but only to 75%.
Which brings us onto the scientists who refused to sign the declaration.
They didn't refuse because they thought the group's demands were overstated, but because they thought the targets weren't hard enough. For them, the statement was not alarmist. It had failed to be alarming enough.
All this made me think of Mark Lynas's recent bookwhich I read on the plane on the way over (yes, I am aware of the irony). It devotes each of its six chapters to a degree of global warming - 1 degree is not too bad, 2 begins to look pretty awful. By the time you get to 6 degrees, humanity's extinction is only a footstep away. Oh and most other species get the boot as well.
Lynas is also at pains to argue that it may already be TOO LATE. He too gives us only half a chance of avoiding runaway climate change:
[quote]In my view there is now probably less than a fifty-fifty chance of avoiding runaway global warming, given the danger of escalating positive feedbacks and the staggering, geologically unprecedented rate at which we are dumping carbon into the atmosphere.[/quote]
Lynas's book really packs a punch because he wrote it by trawling his way through thousands of scientific papers. He's the epitome of the generalist, forming a broad overview of the state of the scientific debate, at the expense of deep knowledge of any of its components.
It's only towards the end of the book that he really starts guessing. But that's only because few studies have been done on what will happen if temperatures rise that high.
Now, of course, my failed attempt to end it all in the airplane toilets, using a plastic knife from the food tray, caused quite a scene. And I have to admit that the resulting wound has caused quite a stir around the media centre, where more respectable hacks keep me at a safe distance.
Arriving in Bali, I was enormously relieved to see a review of the book had been published just a short while ago by RealClimate, a website that offers ‘climate science from climate scientists.' I am in no position to judge whether the science it offers is good science, but it seems a sober enough place.
Here surely, Lynas's book would be given the good kicking that it surely deserves. His presumption to go to the original sources, rather than rely on the IPCC's synthesis, would be cruelly exposed.
Not a bit of it. 'It doesn't tend to go beyond the published literature,' Eric Steig notes approvingly. 'This is what Lynas claims at the outset - "all of the material in the book comes from the peer-reviewed scientific literature" - and I think he does an admirable job.'
Steig then poses an intriguing question (I strongly recommend you read some of the 173 comments to get a flavour of the replies):
[quote]If a reading of the published scientific literature paints such a frightening picture of the future as Six Degrees suggests - even while it honestly represents that literature - then are we being too provocative in the way we write our scientific papers? Or are we being too cautious in the way we talk about the implications of the results?[/quote]
As I left the panel, I ended up wishing that I'd asked the scientists today precisely this question. Indeed, this evening, I have been trying to raise some of them on their mobiles, though I suspect they are contentedly tucking into a well earned dinner.
They, and the IPCC, for understandable reasons, prefer to talk about what happens if things go well, while Lynas has spun a web out of the scientific literature's darker findings. In the end, it all boils down to our appetite for risk.
From the panel today, Richard Somerville, one of the leading lights of IPCC's working group 1, made the point rather well:
[quote]We're speaking here about a topic that is hard for the public, and maybe some politicians, to grasp, which is that we're speaking about risk, about probabilities and likelihoods. There isn't a magic number...below which you're safe and above which you're not.[/quote]
'It's simply a risk factor,' he says. In other words: what kind of chances with the future are we prepared to take?