Nigel Lawson, one of Britain’s Chancellors of the Exchequer during the Thatcher Era (Secretary of the Treasury for those needing a US translation) and more recently known as the father of Nigella Lawson (a UK cooking diva), has weighed into the climate debate with a recent broadside calling for the abolition of the IPCC (Intergovernmental Panel on Climate Change). Based on a curious report by the UK House of Lords Economics Affairs committee (in which they made clear that they had no scientific expertise), Lawson demands that the only global scientific assessment process on climate change be shut down, and replaced with ….well what exactly?
It is worth re-iterating what role the IPCC and other scientific assessments (another example being the WMO biennial report on ozone depletion) are supposed to play. Even for experts in any particular field (and definitely for policy makers), the vast scientific literature needs to be distilled and summarised. In the first instance this must be done by scientists who are in that field and familiar with it. Where there is a widespread consensus, and where there are substantial debates or important uncertainties should be made clear. Open expert review is crucial in ensuring that these distinctions are agreed to by most of the field.
It should go without saying that the assessment bodies should be international in scope to avoid the impression that they are somehow pushing national agendas in very sensitive areas such as energy or trade. It is also vital that the process of scientific assessment is completely separate from the any proposed policy recommendation: the science should inform the policy, not determine it. To that end, there are three working groups in the IPCC: Working Group I deals with the scientific issues regarding climate change (and is the group that we at RealClimate are most involved with), WG II deals with potential impacts, and WG III deals with potential policy options.
The heart of Lawson’s case is the economic criticism of the IPCC scenario generation process which has been pushed by Ian Castles and David Henderson. We are not economists and so we won’t engage in the specifics of this criticism, but as consumers (so to speak) of the product, it’s worth making a couple of relevant points. First, it should be emphasised that the scenarios are used solely for the providing input into climate models, and not for generic economic planning decisions. Therefore only the final differences in the total greenhouse gas emissions actually matter. From reading the Committee report itself, these differences in emissions for one particular scenario are only around 15% by 2100, and only lead to a 0.1 deg C difference in temperature by 2100 (Table 3, p39) – and this is certainly much less than the spread among the different storylines, and so is unlikely to affect the range of climate model results.
A second point worth making is that IPCC is not the sole supplier of scenarios. The GISS group has developed its own ‘alternative scenarios’ (assuming relatively aggressive attempts to reduce emissions for instance, something IPCC explicitly does not consider), and any other group is free to do the same. If they are significantly different from the standards, other groups could be expected to run them as well. In and of itself this line of criticism clearly does not imply that IPCC should be abolished as an institution, since of course the scenario generation and their use in future projections only makes up a very small part of the scientific assessment process.
However, Lawson’s claims that IPCC’s ‘ignoring of dissent’ is a ‘scandal’ betrays a fundemental ignorance of how the IPCC works. The last IPCC report (TAR) was published in 2001. It will assess the validity of any criticisms published in the scientific literature in its next report, due in 2007. The IPCC makes its assessments in a very thorough writing and review process involving hundreds of scientists, open to critics, with transparent and predefined procedures. That it makes no proclamations in between the full assessments is not a ‘scandal’, it simply is sticking to its sound and transparent procedures.
The vast majority of studies since TAR have reinforced the conclusions made then, and so it is likely that the 2007 report will be very similar in its conclusions. Of course, it isn’t possible to keep everyone happy, so what happens when small but vocal minorities start complaining that they have been shut out of the process, their views marginalised and the ‘establishment’ is somehow persecuting them?
Much of the time these ‘outsider’ critiques are not based on anything other than a desire to confuse (claims that IPCC doesn’t mention water vapour feedbacks for instance, or that there is a deliberate attempt to downplay solar effects on climate or that the number of vineyards in England a thousand years ago implies that CO2 has no radiative effect) and have no traction in the scientific community. These critiques are therefore easily dismissed. More substantive potential criticisms based on peer-reviewed literature (which may or may not be correct) have to be considered more carefully in the context of similar studies and relevance, and that is generally what happens. In the end though, most outlier results do not end up in the mainstream, though investigating them often leads to a better understanding of the process (Lindzen’s Iris effect is a case in point).
However, the bulk of Lawson’s case actually appears to stem from a confusion between the IPCC and the policy options exemplified by the Kyoto Protocol. These are two quite separate things. As Roger Pielke Jr is fond of saying (and with which I agree), scientific description of a problem does not imply a specific policy response. In this case, while the Kyoto process is an attempt to deal with the problems highlighted by the IPCC, it was neither suggested, nor prescribed, by that body. Therefore, what balance between adaptation (dealing with whatever happens) and mitigation (doing something about the emissions that contribute to climate change) is likely to be more cost effective is not a question within the remit of the IPCC (although many options are discussed in the WG III report). One point worth making is that if Lawson really feels that the high end emissions forecasts are unrealistic, then the costs of keeping to a climate-based target are much less – ‘Kyoto for free’ as it were.
Lawson suggests that economic issues related to climate change should be discussed within economic departments of government, and I doubt anyone would disagree. He goes further though and calls for the dismantling of the IPCC and it’s functions to be transferred to the existing Bretton Woods institutions (that is, the World Bank and the International Monetary Fund). This is surely a mistake. IPCC is tasked with the scientific assessment of climate change, handing that function to economic institutions not heretofore known for their scientific expertise would surely be an error. Just how much of an error is revealed by Lawson’s last paragraphs in which he, ironically, he uses the notion of a scientific consensus to combat (admittedly widespread) popular claims of a direct link between the individual impacts of Hurricanes Katrina and Rita and global warming. Since no scientists have made a claim of direct cause and effect (see our recent post on potential statistical links between hurricane intensity and tropical warming), any scientific assessment (such as the next IPCC report) will certainly not do so either. It is precisely because such anecdotal ‘science’ is not a balanced picture of the state-of-the-art that IPCC exists in the first place. And if IPCC did not exist, it would be necessary to invent it….
Update 20 Dec 2005: The response of the UK government to the HoL report was published Nov 28.