IPCC Fifth Assessment Report

Debate between Lord Lilley and Ian Lavery

Thursday 20th November 2014 Westminster Hall

[Mr Peter Lilley (Hitchin and Harpenden) (Con)]

I apologise to you, Mr Betts, and to my hon. Friend the Member for South Suffolk (Mr Yeo) for arriving a few minutes late and missing some of his opening speech. It is a pleasure to follow the hon. Member for Blackley and Broughton (Graham Stringer), who made an important contribution to this debate, as he does to the Committee’s deliberations. The report, of course, was not unanimous. Both he and I voted against it. I think we were able to secure the inclusion of only one of his amendments, but that is not because either of us denies the basic science of the greenhouse effect. He can speak for himself, but we are both scientists by training, which is a characteristic that is not shared by most members of the Committee. We do not dispute the greenhouse effect, nor did any of our witnesses. However, great uncertainties remain about how much warming a given increase in greenhouse gases will cause, how much damage any temperature increase will cause and the best balance between adaptation and mitigation in response to, or in pre-emption of, global warming.

The main bulk of the IPCC technical report recognises those uncertainties, and the report is simply a useful compilation of research in the field. My criticisms are about the summary for policy makers, which is far less balanced than the report it purports to summarise. The hon. Gentleman explained the process by which the summary was produced, which may be why it is so less balanced. The summary is essentially a document of advocacy, and it achieves its objective of influencing policy makers, as its title indicates, by the selective use of facts and the omission of quite a lot of the stuff in the main report, including some of the most significant changes, which are simply not drawn to the attention of policy makers. I am not the first to criticise the IPCC process.

[Ian Lavery]

This is a general point. Would the right hon. Gentleman describe himself as a climate change sceptic?

[Mr Lilley]

Yes. I normally call myself a lukewarmist. I believe that the climate will warm a bit, which will probably be quite beneficial to parts of our country, although it could pose problems elsewhere. I do not deny that double the amount of CO₂ in the atmosphere will increase the temperature by 1° and a bit, plus or minus any effect due to positive or negative feedbacks. However, I do not think that the evidence shows that the change will be very large. I will come to that.

It is not just climate sceptics and I who have been critical of the IPCC’s tendency to exaggerate. Following the discovery of inaccuracies, use of grey data and so on in AR4, the fourth assessment report, which forecast that all the glaciers in the Himalayas would melt in 35 years rather than 350 years, the InterAcademy Council—the council of all the main scientific academies in the world, including our Royal Society, the US scientific bodies and so on—carried out an investigation of how the IPCC worked. The IAC was critical, particularly of authors who

“reported high confidence in statements for which there is little evidence”.

It is not just fellow sceptics and I saying it; all the scientific academies of the world, which by and large have signed up under some political pressure to rather unscientific statements about global warming, have considered the IPCC report and concluded that some scientists, although not all, tend to report high confidence in statements for which there is little evidence. The IAC therefore recommends:

“Quantitative probabilities (as in the likelihood scale) should be used to describe the probability of well-defined outcomes only when there is sufficient evidence. Authors should indicate the basis for assigning a probability to an outcome or event (e.g., based on measurement, expert judgment, and/or model runs).”

No such basis for assigning enhanced probability was given when the most recent IPCC report came out. Its headline conclusion was that the evidence for human influence has grown since the fourth assessment report, and it went on to attach increased likelihood—categorised on the scale as “extremely likely”, rather than the previous “very likely”—to the possibility that human influence has been the dominant cause of the warming observed since the mid-20th century. That was the overall headline assessment to which the IPCC wanted policy makers to respond. However, it is hard to back up that conclusion from the substance of that report. Since the last report, we know what has happened.