Until last December, a very large majority of the scientific community and most politicians would have agreed that the scientific evidence of human-induced climate change was unequivocal and that the sole question was whether the world’s political leaders could agree in Copenhagen to meaningful, legally binding greenhouse gas emission reduction targets. But, as we now know, the negotiations only produced an aspirational target of limiting the global mean surface temperature to no more than 2 degrees C above pre-industrial levels and an accord that does not bind any country to reduce its emissions.
Since then, there have been reported errors and imprecise wording in the Fourth Assessment report of the Intergovernmental Panel on Climate Change (IPCC), issued in 2007. These include the hyped statement that Himalayan glaciers would melt by 2035 or earlier (the IPCC admitted that this was an outright error and not evidence-based); that agricultural production in some North African countries would decrease by up to 50 per cent by 2020 (the synthesis report failed to include the nuances and more detailed discussion in the underlying chapter); and that over half of the Netherlands was below sea level, rather than a quarter. (This was largely a definitional issue - the Dutch Ministry of Transport uses the figure 60 per cent below high water level during storms.)
These errors or imprecise wording in the IPCC’s 2007 Working Group II report, coupled with the issues surrounding the hacked emails and temperature data from the University of East Anglia, have provided the climate sceptics and some in the media with ammunition to undermine public confidence in the conclusions of the IPCC and climate science in general.
Clearly, the language in the leaked e-mails could suggest that the scientists may have inappropriately manipulated the data to support the theory of human-induced climate change and attempted to suppress other data that contradicts this theory. That is why I applaud the University of East Anglia - affiliated with the Tyndall Center for Climate Change Research, where I work as strategic director - for rapidly establishing an independent review of the whole issue. But to suggest that the hacked emails or the identified inaccuracies in the IPCC’s Working Group II report undermine the broad evidence that the Earth’s climate is changing due to human activities - or that any talk of carbon emissions cuts should be suspended - is simply untenable.
Recently, the UK Royal Society, the National Environment Research Council and the UK Meteorological Office issued a joint statement not only supporting the findings of the 2007 IPCC report, but showing that recent scientific information further strengthens those conclusions. The statement concluded that these agencies could not emphasise enough the body of scientific evidence that underpins the call for action now. Also, a statement from 11 science academies in developed and developing countries concluded that climate change is real, and that we need to prepare for the consequences, and urged all nations to take prompt action to reduce their greenhouse gas emissions.
So let me return to the issue of the IPCC, which is one of the most rigorous scientific review bodies in existence. Many thousands of scientists have dedicated their time to preparing and reviewing the most comprehensive and authoritative assessments of climate science available. In addition, governments from around the world have reviewed and approved the IPCC’s key findings. The reports undergo two rounds of peer review, and the policymakers’ summaries of the working groups are then subjected to a word-by-word approval of all governments in the presence of the chapter lead authors.
In many cases, the IPCC is very conservative in its statements, e.g., the projections of sea level rise reported in Working Group I were based on contributions from thermal expansion of the oceans and the melting of mountain glaciers, but did not contain a contribution from the melting of the Greenland ice sheet, due to an inadequate understanding of the current rate of melting.
Some would say that only four mistakes or imprecise wording have been found in the 1,000-page Working Group II report, and none in working groups I and III, and so would ask: Is there really a problem? But given that each of the mistakes overstated the implications of climate change, it is critical to regain any lost trust from the media, public, governments, and private sector. The IPCC could start by posting all errors - accompanied by explanations of how they were made - on its web site.
I see no evidence that the authors purposely overstated the potential impacts from climate change in an effort to convince the public of the seriousness of the threat. The threat is serious enough without the need to hype the issue. But the expert and government peer-review process should have caught these inaccuracies and careless wordings. The vast amount of attention in the print and TV media, especially in the UK, has clearly left some of the public confused, if not sceptical.
The challenge now is to regain any lost trust through a continuing re-examination and restatement of the evidence, clearly identifying what we know and what is still uncertain. It is critical that the public understand the issue of climate change, given the need to both mitigate and adapt in a cost-effective and socially responsible manner.
So does the IPCC process need to be significantly revised? I would argue no, that the IPCC is more than capable of conducting rigorous and reliable assessments in an open, transparent, and inclusive manner. But the IPCC needs to regain its full and deserved credibility. The procedures for the selection of authors and review editors and the peer-review process and approval of reports are all sound. What is needed is to tighten up the implementation of these procedures, coupled with training of authors and review editors. The selected authors need to represent the full range of credible views, including those of the sceptics, and must ensure that all statements are based on sound science and that the citations used contain convincing evidence.
The IPCC should consider shorter reports focused on the key issues, rather than the all-encompassing reports that have become the norm. Authors, peer reviewers, and the working group secretariats need to be absolutely rigorous in ensuring that all conclusions are backed up by evidence, with an accurate assessment of how good the evidence is, and that all of the citations are valid. Gray literature - i.e., the use of non-peer-reviewed literature - can and should be used as long as it is evidence-based and available to the peer reviewers for evaluation.