OPINION: True nature of climate change 'highly uncertain'

John Woods, Director of Friends of the Earth Northern Ireland, asserts in his September 11 opinion piece: "The UN's Intergovernmental Panel on Climate Change, which draws together the work of over 2,500 scientists, has concluded that most of the increase in global temperatures since the mid-20th century is very likely due to the increase in greenhouse gases from human activity."

This is a highly misleading statement.

Here's the real situation.

The UN's Intergovernmental Panel on Climate Change (IPCC) puts out "assessment reports" every five years or so, its latest being the much cited 2007 Fourth Assessment Report.

Each assessment report covers the work of three working groups.

The approximately 1,000-page Working Group I (WG I) report, entitled The Physical Science Basis, contains the assertion made by Mr Woods above; its exact wording is found in Chapter 9, Understanding and Attributing Climate Change, and is the following: "Greenhouse gas forcing has very likely caused most of the observed global warming over the last 50 years."

So how many of the 2,500 scientists who reviewed parts of the complete IPCC report actually reviewed this statement?

Very few indeed.

We know this because, for the first time ever in 2007, the UN released on the Web scientist reviewers' comments concerning the drafts of the WG I report and the IPCC editors' responses.

An examination of reviewers' comments on the last draft of the WG I report before final report assembly (i.e. the Second Order Revision) completely debunks the illusion of hundreds of experts diligently poring over all the chapters of the report and providing extensive feedback to the editing teams. What we find is that a grand total of 62 reviewers commented on the critical Chapter 9; in other words, 2.5 per cent of the total 2,500 participants.

Of the comments received from the 62 reviewers of this critical chapter, almost 60 per cent of them were rejected by IPCC editors.

And of the 62 expert reviewers of this chapter, 55 had serious vested interests (being employees of governments that already had decided on the outcome, for example), leaving only seven expert reviewers who appear impartial.

Two of these seven had interesting comments about the IPCC Chapter 9 statement that Mr Woods implies 2,500 IPCC reviewers support:

Dr Ross McKitrick of the University of Guelph, Canada said, "A categorical summary statement like this is not supported by the evidence in the IPCC WG I report. Evidence shown in the report suggests that other factors play a major role in climate change, and the specific effects expected from greenhouse gases have not been observed.”

Dr Vincent Gray of New Zealand, an IPCC Official Expert Reviewer since the organisation started, called the IPCC Chapter 9 assertion “typical IPCC doubletalk” and concluded: “The text of the IPCC report shows that this is decided by a guess from persons with a conflict of interest, not from a tested model.”

A determination of the level of support among the 62 reviewers of Chapter 9 is subjective but a generous evaluation indicates that just five reviewers endorsed the chapter as a whole.

Of these, four had vested interests and the other made only a single comment for the entire 11-chapter report.

Mr Woods’ implication that 2,500 independent scientist reviewers agreed with this, the most important statement of the recent UN climate reports, is clearly nonsense.

Leading Canadian climatologist Dr Timothy Ball sums up the situation well: “The IPCC owe it to the world to explain who among their expert reviewers actually agree with their conclusions and who don’t.

“Otherwise, their credibility, and the public’s trust of science in general, will be even further eroded.”

Mr Woods is however justified when he encourages Environment Minister Sammy Wilson to “get on with the job for which he is being paid”.

And the job for which he draws his salary is to protect the environment, while keeping the needs of the economy and Northern Ireland’s citizens front and centre; telling the truth about the highly uncertain nature of global climate change is an exceptionally good place to start.

Mr Wilson is setting an example environment ministers across the world would do well to emulate as the public come to understand the vast uncertainty that remains in this, the most complex field of science humanity has ever tackled.