IPCC under the microscope – but isn’t that what science is all about?

The controversy over errors in the IPCC's assessment of climate change have people asking whether it's all a beat-up. But where's the peer reviewed evidence that no risk exists, asks one of the IPCC's authors

As has been well reported recently by the media, several errors have emerged from the IPCC 4th Assessment Report (AR4) published in 2007. Since the three main volumes each contain around 600 pages of text based on a detailed analysis of thousands of scientific papers and reports, then it is perhaps not surprising that an occasional mistake has been made. After all, it was written and published by humans, and humans, whether doctors or pilots or IPCC authors, do occasionally make mistakes.

The IPCC writing process is unique. To illustrate this, let’s take the Energy Supply chapter of the “Mitigation” volume of the AR4 (for which I was the co-ordinating lead author). My team of 14 authors, (selected by the IPCC from numerous nominations as proposed by governments from around the world, and then approved at a plenary meeting attended by maybe 150 member countries), wrote the “zero-order-draft” of the chapter over several months. The text produced was a summary of the current knowledge taken from the literature and presented in an unbiased way.

Where there is uncertainty, or a scientific debate on a specific topic is in progress, then these are reported in the text. This draft, along with the other 10 chapter drafts, was circulated around the whole team of maybe 150 authors for them to look for gaps and overlaps. It was then rewritten and the “first-order-draft” sent out for review to hundreds of experts from around the world. Their comments were discussed by the author team, a response to each was recorded (e.g accepted; declined because….;  not relevant to the topic) and these responses were saved by the IPCC Technical Support Unit in case subsequent queries were made.

The “second-order-draft” was then prepared incorporating these review comments, and sent out again to more expert reviewers as well as to government officials. Their comments were again reviewed then incorporated into a revised text that became the final draft. My chapter alone received over 5000 comments that each needed a written response.

It was at this late stage of the writing process for the “Adaptation” volume of the AR4 that the “Glaciergate” comment – an erroneous claim that Himalayan glaciers could melt away by 2035 – was added to the text, possibly as a result of a reviewer’s suggestion.

The error made by the author of this section was to have not adequately checked that particular reference prior to amending the text and including it. But then he or she was human, and probably, like most authors, under tight deadlines and also with a full-time position to maintain.

An error has also recently been found in my Energy Supply chapter, as reported in the British Sunday Telegraph recently.  Somebody had gone to the trouble to find out that a figure of a map of the world showing the various average annual wave power density fluxes (kW/m2) along the coastlines of the continents, had three or four numbers differing from the original version that can be found on the referenced web site.

I have been through all the drafts of the chapter since then and the correct version of the map exists in all of them. Therefore, the only explanation for this error was that when the figures were redrawn by the publisher of the final report, the graphic artist, (also probably a human!), made some errors that were not subsequently picked up.

Interestingly, the incorrect numbers made absolutely no difference to the text which simply states, “The best wave-energy climates (Figure 4.16) have deep-water power densities of 60–70 kW/m but fall to about 20 kW/m at the foreshore. Around 2% of the world’s 800,000 km of coastline exceeds 30 kW/m, giving a technical potential of around 500 GW assuming offshore wave-energy devices have 40% efficiency.”

Hardly a headline grabbing statement, with or without the errors appearing on the revised figure – and certainly not critical enough to make it into the Synthesis Report (that brings the Climate Science, Adaptation and Mitigation volumes together) or into the “Summary for Policy Makers” (SPM) of the Mitigation volume.

The SPM process is worthy of note. The 600 pages of text was edited by lead authors down to a Technical Summary of around 70 pages and also to the SPM. These 28 paragraphs were then presented sentence by sentence to, in this example, 154 teams of national climate negotiators, some of up to ten people, others of only one. Unanimous approval needed to be sought on each sentence, which is why the operation took over four days to complete. The single sentence on nuclear power, for example , took over 6 hours to gain agreement, and even then at 2.30 in the morning, Austria could not agree, as was shown in the SPM footnote.

The key point relating to the SPM is that every statement has to be backed up by details reported in the main text. With over 1000 people in the room following proceedings, including representatives from NGOs, industry, civil society, etc. there was little chance to bias the scientifically-based summary findings as some people have claimed.

So the questions beg:  Who is digging very deeply into the AR4 looking for errors over three years after it was first published? What is their ambition? Are they trying to undermine the IPCC process? Who, if anyone, is paying them to do it?  Has the media now unjustly brought into question the whole of climate science as a result of these relatively minor errors?

There is no doubt that IPCC authors, like virtually all other authors, have made a few errors. There is no doubt the IPCC process, like any scientific analysis, must be totally transparent and open to critique and question by climate sceptics, the media, policy makers and the public at large. There is certainly a good case for reviewing the whole IPCC process to see if it can be improved and hence try and avoid such errors in the future as far as is humanly possible.

But surely the most critical question of all is whether the threat of climate change, as presented by the science, has been now shown to be lower than was originally thought. If we take out of the equation the East Anglia models (accepting that such e-mails as reported were somewhat bizarre); the erroneous glacier report; the poorly analysed African food paper; the ocean energy potential error; and any other errors maybe still to be uncovered out of the thousands of pages, then can someone now produce a scientific paper arguing that there is NO RISK to mankind from anthropogenic climate change?

Science, like medicine and insurance, is largely based on risks and probabilities. If the current knowledge of, say, bone cancer, informs a patient that there is only a 20% chance you will survive without having an operation but a 90% chance you will be bed-bound if you have one, it is not an easy choice to make. Do nothing might be the best option. If current scientific knowledge is telling us that there is “high agreement and much evidence” that the world is warming, most probably due to human influence, certainly we still need to question the science and gather more information as time goes on. But do we do nothing and just hope it all goes away?

For those who have uncovered the errors in the AR4, I for one am extremely grateful. We must always be willing to learn from our mistakes. The fact that they were not picked up earlier during the stringent IPCC review process makes it all the more important that they have been now.

I would be extremely grateful if those involved, obviously with enough time available to go through the report in such detail, would be willing to become reviewers of the 5th Assessment Report, or indeed the IPCC “Special Report on Renewable Energy” that is currently under review at its first-order-draft stage. Their input would be invaluable to help find any errors overlooked by us lesser humans so that corrections can be made prior to publication.


Prof. Ralph Sims is the director of Massey University's School Centre for Energy Research.