Open letter to Piers Corbyn

Piers Corbyn is a physicist who has published research on superconductivity, cosmology, solar physics, Sun-Earth relations and the weather. He runs a commercial weather forecasting business (www.weatheraction.com) and disagrees with the IPCC consensus on global warming.

Piers has challenged the IPCC '...to admit that there is no observational evidence … that CO2 levels (whether from man or nature) have driven or are driving world temperatures or climate change'. He’s issued a general challenge: 'If you believe there is evidence of the CO2 driver theory in the available data please present a graph of it'.

Here is my reply to the challenge.

Dear Piers,

Let me respond to your request for evidence by explaining why I won’t be providing any.

Since I’m not a climate scientist I must, even though I have a science degree, approach the issue as an informed layman. How is the informed layman to proceed in such a case?

a) He can ask whether the claimed effect is plausible based on what he does know. For instance I know that CO2 is a greenhouse gas, that there’s more in the atmosphere than there was before the industrial revolution and that temperatures and sea levels are rising globally. Now that doesn’t prove causation but it is consistent with it.

I also know that most of the reports I see on advances in climate science (in New Scientist for instance) suggest that change is now happening faster than was expected in the last IPCC report.

b) He can ask whether MOST of those who are competent to form a genuinely independent scientific judgement are agreed. In this case there’s a very broad agreement that increases in atmospheric CO2 are driving global warming. He’s entitled to note that there are always dissidents in science. Their existence is not evidence that the consensus is wrong.

c) He can ask whether the issue has thoroughly studied. Given the IPCC process climate change has perhaps been studied more thoroughly than any other comparable question.

d) He can ask whether the consensus is getting stronger or weaker. Plainly it’s getting stronger.

e) He can ask whether vested interests have been operating so as to undermine the science. In this case some of the world’s strongest vested interests have lobbied against accepting that increases in atmospheric CO2 are driving global warming:

• The White House has censored US government scientists.
• It has also pressed for the weakest form of words in IPCC drafting work.
• Major multinationals have paid supposed climate scientists to contest the consensus in just the way that Big Tobacco sought to resist the evidence on smoking. (NB I don’t, of course, suggest you have been suborned in this way.)

f) He can ask whether people he knows personally have well-founded views on the science. In this case I know you. But I also knew David King at UEA’s School of Chemical Sciences in the 70s. So let’s call that a tie.

g) He can ask whether prominent non-scientists who are well advised on the science have accepted the consensus. Here I see that the Nobel Peace Prize Committee, the UK Prime Minister, the US President and an overwhelming majority of senior business executives polled by McKinsey last year have either accepted or moved towards acceptance of the consensus. Insofar as any of these have a vested interest it lies for the majority in denying, not affirming, the evidence for man-driven climate change. Evidence against interest always weighs more heavily than the contrary.

So out of the seven tests that I, as an informed layman, can make six encourage me to believe that increases in atmospheric CO2 are driving global warming. One is inconclusive. Actually, that’s about as good as it gets.

Now none of this creates certainty but neither, in practice, does science. Science is always somewhat provisional.

The real question now is that of public policy and here a version of Pascal’s Wager applies. If the consensus is right it would be dangerous to the lives of many people to wait the years that may be needed to approach certainty more closely. If the consensus is wrong and we act as if it were true we will waste money on insulation, wind farms and carbon offsets and some of us will take fewer foreign trips.

Morally, I don’t find that a difficult decision.