The first, and arguably most important, part of the latest IPCC Assessment Report (AR5) will be released next week in Stockholm (IPCC). This is the report from Working Group 1, charged with evaluating the current state of knowledge on the physical science. The reports from WG2 (Impacts, Adaptation and Vulnerability) and WG3 (Mitigation) will follow next Spring, with the final Synthesis Report being launched in October in Copenhagen (host city to the ill-fated 2009 COP15 conference).
Despite attempts to control the spread of information, the blogosphere has inevitably been full of leaks and previews of what the reports will say. The WG1 report is the most important because the conclusions it comes to shape the entire exercise. If the authors were to conclude that Mankind’s contribution to the present phase of climate change was less important than previously thought, then the world would pay much less attention to the need to mitigate.
But it is clear that the opposite is true; the crucial statement from the current version of the Summary for Policymakers (the SPM, the only bit which most people actually read) is “It is extremely likely that human influence on climate caused more than half of the increase in global average surface temperature from 1951-2010.” The important thing to note here is that this is an increase in confidence since AR4, despite the trend in warming having fallen to the bottom end of the range predicted earlier (and below this by some estimations).
Rather naively, the IPCC leaked the SPM to ‘friendly’ journalists in an attempt to manage the news of the report’s launch. However, inevitably it ended up in less friendly hands and has come in for some fierce criticism. There is no room here to do justice to the ongoing debate which is now rising to a crescendo, but readers who want to get a flavour of it could do worse than read these blog postings: Leaked IPCC report discussed in the MSM and Excerpts from the leaked AR5 Summary for Policy Makers. The first is from Judith Curry, a thoughtful scientist who supports the enhanced greenhouse effect hypothesis but is often critical of the IPCC and some of its more enthusiastic supporters. The second is by Anthony Watts, a retired meteorologist and author of a sceptical but reasoned blog.
Judith Curry makes the point that, in light of the accrual of evidence over the five years since the publication of AR4, the increased confidence is unjustified (remember that the confidence levels are a matter of subjective judgement; there is no objective metric used). In her words “An increase in confidence in the attribution statement, in view of the recent pause and the lower confidence level in some of the supporting findings, is incomprehensible to me. Further, the projections of 21st century changes remain overconfident.”
This topic is vitally important for the future of all of us. If the IPCC’s confidence is justified then effective mitigation measures should be given high priority. The debate then moves from what the problem is to how best to solve it, whether by making the most cost-effective reductions in carbon dioxide emissions now (almost certainly with a large element of nuclear power), concentrating on adaptation or simply waiting until future generations have new, economic energy generating technologies which do not use fossil fuels. The IPCC seems to be trying to move the debate on and once again persuade leaders that ‘the science is settled’.
If, on the other hand, the WG1 authors’ confidence is misplaced, then the case for rapid and radical decarbonisation is undermined. The fact that there is no end in sight to China and India’s escalating use of coal might already be seen as making current policies futile, but it has not stopped the EU and a few other enthusiastic countries from imposing high costs on their own economies to reduce their own use of fossil fuels. If the IPCC’s apparent certainty can be shown to be unjustified, then pragmatic politicians are going to have to start questioning their emissions reduction policies.
To add to this mix, there is a recent report of further work by the Danish team led by Henrik Svensmark on the influence of the Sun’s magnetic field on cloud formation initiated by cosmic rays: Physicists claim further evidence of link between cosmic rays and cloud formation. What the latest experiments have shown is that the very fine aerosol particles produced by ionising radiation can aggregate in the presence of sulphuric acid (produced under the influence of ultraviolet light) to produce nuclei large enough to initiate cloud formation.
By itself, this if of course not enough to demonstrate that cosmic rays, mediated by the Sun’s changing magnetic field, have a significant effect on global temperatures relative to the forcing effect of atmospheric carbon dioxide. However, the evidence which is building cannot be ignored. This does not stop this hypothesis being effectively dismissed by the current climate change Establishment, who have consistently said that such an effect could only be minor. In this report for example, Gavin Schmidt, a leading spokesman, said "The researchers have a really long way to go before they can convince anyone that this is fundamental to climate change."
This is undoubtedly true, but we should not forget that the entire edifice of climate change policy currently rests on the output of computer models based on the hypothesis that there are positive feedback mechanisms which increase the modest warming impact of higher CO2 levels. There is currently no empirical support for this and the temperature trends for the early part of the 21st Century are now incompatible with the projections from the models. It would be foolhardy to ignore hard evidence of other effects, even if IPCC scientists are dubious. Our future prosperity may depend on it.
Martin Livermore
The Scientific Alliance
St John’s Innovation Centre
Cowley Road
Cambridge CB4 0WS
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