They say that the key to judo is to use your enemy’s strength against them. It’s certainly a very neat trick if you can pull it off – allow the opposition to stake everything on a position they think is secure, then pull the rug away and let them fall.
A similar thing has just happened in climate science. The UN’s Intergovernmental Panel on Climate Change (IPCC) has for 25 years shaped the discussion on global warming. It has set the scientific terms of reference and it has formed the political position it expects governments to take – that global warming is real and man-made and poses a terrible threat to the continuation of civilisation.
Over the years, as the actual data gathered from the real world has become steadily less alarming (no warming since 1998, no total loss of Arctic ice, record increases in Antarctic ice, etc.), the IPCC’s Summary for Policymakers (SFP) has nevertheless remained packed with reasons for politicians to keep pumping funds into disastrous wind farms and other gross wastes of public money. In the most recent IPCC report, the Fifth Assessment Report (AR5), the SFP became more detached from the data than ever.
However, given that the IPCC claims to be a scientific rather than political body, it still ultimately has everything staked on the science. The single most important issue in all of the scientific debate is the expected response of the climate to a doubling of atmospheric CO2. This is known as the climate sensitivity and if it is high then we are in trouble and if it is low there is no good reason to panic about CO2. (There are actually two types of climate sensitivity, one for short term effects and one for the longer term, but they are closely related and for reasons of simplicity I’ll treat them as one here.) In AR5 the sensitivity was estimated to lie between 1.5°C and 4.5°C; it is generally agreed that if it is less than 2°C we are pretty much OK and if it is more than 3°C there will be serious trouble.
Curiously, AR5 declined to give a best estimate between these two numbers, despite previous IPCC reports having done so. The SFP however latched onto the fact that the range was closer to catastrophe than safety and advised accordingly.
There the story would normally rest, but in the last few days Nic Lewis (an independent researcher) and Professor Judith Curry (a climatologist) have published a paper that puts the IPCC in one hell of a judo hold. They have taken the IPCC’s own data and methods and calculated what that crucial ‘best estimate’ should have been. To cut to the chase, it comes in at 1.33°C, with a 95% chance it is less than 2.5°C.
Oops. It appears that those of us who think that man-made CO2 will cause some warming, but almost certainly not anything remotely dangerous, were probably right all along.
Now, there are plenty of reasons to think that how the IPCC goes about calculating climate sensitivity is too simple – for example it assumes the climate responds to CO2 in a linear fashion, that is to say for a given change in CO2 the response will always be the same, regardless of how much or how little CO2 is already present. But the key here is that by their own rules, the IPCC is shouting fire in a theatre that steadfastly refuses to burn.
I admit it is early days, and a flaw could be found that discredits the paper – in which case I’ll be editing this essay to admit the fact. But the usual alarmist crowd are yet to publish a single critical article on the paper, or even one acknowledging its existence, which is a good sign.
The most important thing about the paper for me isn’t that it advances our scientific understanding of the climate (for it doesn’t), but that it provides a carrot for both scientists and politicians. I’ve said before that political attitudes to global warming will only change once there is a large enough body of scientific evidence out there for politicians to justify really ditching all the ‘green crap’. And this paper is a milestone in creating just such a body of evidence. It’s a big, fat, juicy carrot, dangling in full view of anyone who needs a reason to moderate their stance on the issue.
There’s certainly a very visible stick at the moment too – Dr Michael Mann’s increasingly farcical defamation lawsuit against columnist Mark Steyn, for calling Mann a scientific fraud. (His famous hockey stick is a fraud, by the way.) Mann has recently been subject to evisceration by piss-taking on Twitter, shown to have knowingly submitted false statements in court documents and has failed to muster a single supportive voice in his pleadings. He can’t even back out of his self-created mess, as Steyn is counter-suing, stating the obvious: that Mann’s original suit is vindictive and aimed squarely at supressing criticism of Mann’s work. This courtroom drama, folks, is the biggest, most gnarled stick possible to complement Lewis and Curry’s carrot.
That there is movement afoot in the scientific community has recently been shown by an opinion piece published in the Wall Street Journal entitled ‘Climate Science is not Settled.’ It is written by Steven Koonin, a theoretical physicist who is chairing the American Physical Society’s review of their public policy statement on global warming. Given that the previous APS statement on the topic claimed that “The evidence is incontrovertible: Global warming is occurring,” the mere title of the new article shows just how much the ground is shifting.
A carrot, a stick, and evidence that positions are shifting: it’s all rather good news, isn’t it?