The European Union have set a goal for international climate policy: The world should not warm more than 2°C above pre-industrial temperatures. This is an ambitious target. As the warming response to the enhanced greenhouse effect is so uncertain, it may imply that the atmospheric concentration of carbon dioxide could not rise much above 400 ppm, only some 20 ppm above today. If recent trends continue, the 400 ppm level would be reached by 2020. A 400 ppm target may require zero carbon emissions, worldwide, by 2050.
One may of course dismiss the European target. Who are they to decide on a global target? Perhaps the target is just political posturing and wishful thinking, or maybe it is just the opening bid in international negotiations. Perhaps European policy makers have been led to believe that deep emission reduction is easy and cheap. However, the European Union is a major player in international climate policy, and its 2°C target deserves serious discussion.
Unfortunately, the European Union seems unprepared for such as discussion. The 2°C target can be traced back to a 1995 report of the German government’s Scientific Advisory Council on Global Environmental Change (WBGU). Estimates of the economic impacts of climate change are a crucial argument in the WBGU report. At that time, the best guess for economic damages due to a doubling of the atmospheric concentration of carbon dioxide was 1.5% of global income. The WBGU raised this to 5.0% without any supporting analysis. Since 1995, economic impact estimates have been revised downwards, but the WBGU has not changed its target.
The WBGU continues to play a substantial role in setting targets for European climate policy. The German government follows its advice. The advisors to the Dutch government just translate its findings. The European Commission leans heavily on its reports. In its latest, 2003, report, the WBGU sticks to the 2°C target. It did revise the justification, however. For this, the WBGU commissioned a report by Bill Hare, a climate campaigner on the payroll of Greenpeace International. The Hare paper is in typical Greenpeace style: Selective citation, quotations out of context, and a focus on alarming examples.
The UK government has not explicitly adopted the 2°C target, but it has been arguing vigorously for stringent emission abatement. The UK position largely rests on two model results, by Nigel Arnell for water and by Pim Martens for malaria. The models predict hundreds of millions of people at risk of malaria and water stress. Unfortunately, these models omit adaptation. Bed nets and perhaps a vaccine could reduce the burden of malaria. Improved irrigation efficiency and desalination can overcome water shortage. Other modellers have been able to include such adaptation, and show that the Arnell and Martens models dramatically overestimate the impacts of climate change
The UK government is obliged to do a cost-benefit analysis of every major project or policy. On climate change, it duly issued a well-crafted report on the social cost of carbon, that is, the target price for carbon permits. The report was well in line with the academic literature, but its summary recommended a number that was an order of magnitude higher than what is typically found in other papers. This has left people wondering, and a review is underway.
The European Commission is also obliged to do a cost-benefit analysis. Its report support the 2°C target. Whereas the UK analysis is sound apart from an unfortunate zero in the summary, the report by the European Commission would fail as a term paper in a course of cost-benefit analysis. In a cost-benefit analysis, one wants to equate the marginal costs and benefits, but the report only looks at total costs and benefits. In fact, the report does not estimate benefits either; it includes all impacts of climate change, not the ones that can be avoided. The impact estimates are over 10 years old, although newer and better studies are available. On the abatement side, the analysis stops in 2025, even though only a fraction of the needed emission reduction will have been achieved by then. The EU report does not review the cost-benefit literature, which reaches different conclusions. A commissioned paper that reached an opposite conclusion was similarly ignored.
I do not believe that there is anything in the literature on the impacts of climate change or the costs of greenhouse gas emission reduction that justifies the deep cuts in emissions necessary to meet the European 2°C target. However, that is not my main point. If policy makers believe that the 2°C target is justified, then they should support that with arguments. Sloppy methodology, selective citations, and exclusive input from environmental NGOs do not make for strong arguments. A democratic government should support its policies with sound science and reasoned judgements. The European climate policy falls short. http://sciencepolicy.colorado.edu/prometheus/archives/climate_change/000718europes_long_term_c.html