A Dutch review of the Intergovernmental Panel on Climate Change (IPCC)'s report brings to light a number of mistakes - some of them trivial, others more glaring - suggesting ways to minimize errors in the future.
The assessment focused on the contribution of Working Group II - on impacts, adaptation and vulnerability - to the IPCC's Fourth Assessment Report.
The review was undertaken following widespread media coverage of erroneous claims that all Himalayan glaciers might melt by 2035 (glaciologists believe they are unlikely to melt so quickly) and that more than 55 per cent of the Netherlands lies below sea level (the actual figure is 26 per cent).
"By and large, the IPCC has delivered a formidable summary of the current state of knowledge. It's not flawless but it is the best we have, and the best we can aim for is to further improve it," Nature quoted Maarten Hajer, director of the Netherlands Environmental Assessment Agency (PBL) in Bilthoven, which carried out the investigation, as saying.
Ironically, the Dutch sea-level error was caused by PBL's own figures.
Martin Parry, a visiting professor at Imperial College London and former co-chair of Working Group II, said: "My authors were certainly bemused to find themselves interviewed by PBL about their work when actually it was PBL that provided the wrong information which caused the furore in the first place."
In 32 projected regional impacts highlighted in the IPCC report's 'Summary for Policy-makers', the PBL came across just one factual error. African population projected to be exposed to climate change-related water shortage, stated as 75 million to 250 million people, should be 90 million to 220 million.
Elsewhere in the IPCC report, a predicted 50-60per cent decrease in the productivity of anchovy fisheries was mistakenly derived from an unrelated study projecting a 50-60per cent decrease in extreme wind and ocean turbulence. Other errors include a handful of incorrect references, table titles and typos.
"'Sloppy' is the relevant word, sadly missing from the report, as it suggests that the errors are neither major flaws in the science nor intended to deceive the reader. Many of the shortcomings noted could be spotted by scientific copy editors and research assistants," Leonard Smith, a statistician at the London School of Economics, said.
The IPCC website has already corrected many of the errors, including the anchovy prediction. However, some like the number of people affected by water shortages in Africa, remain uncorrected, as the IPCC authors stand by their statements.
"I appreciate the importance of placing a clear emphasis on explaining how issues are framed and how conclusions are reached. I also see real value in the suggestion that funding for support staff for IPCC author teams could help insure careful quality checking of every statement," said Chris Field, director of global ecology at the Carnegie Institution for Science in Stanford, California, who now co-chairs Working Group II.
Rajendra Pachauri, chairman of the IPCC, added: "We will of course pay close attention to the PBL's recommendations for strengthening future reports."