3.

IPCC 'measures' uncertainties in terms of level of agreement and consensus and the amount of evidence (theory, observation, models). Uncertainties ask for scenarios. Modern scenario building, French-style, start from combinations of intrinsic uncertainties and it emphasizes the use of scenarios: whatever the scenario may be, one should concentrate on controllability or maitrise, searching for levers of strategic intervention. Scenarios describing worlds concerned about the environment should be decomposed in terms of levers of strategic intervention, say, clean energy, preservation of rain forests and maritime ecosystems, environment-saving conversion of agriculture and exploitation of natural resources.

One must also accept that wen cannot predict. Probable, extrapolated futures of 2100 are rather meaningless because of forecast degradation. Moreover, negative but also positive surprises may occur (even innovations born from serendipity). Or social innovations for that matter, for example, new ways of managing the commons of the earth (read Elinor Ostrom, the other Nobel Prize winner). (Commons are closer to cities and regions, bringing long-term issues closer to home. By the way, the Max-Planck Institute takes commons seriously: a project group is currently studying the Recht der Gemeinschaftsgueter). It is true that non-linear models have greater degrees of freedom than linear ones. The work of IPCC and similar examples of global reasoning tend to play down technological (leave alone social) innovations such as the rise of sustainable energies for fear of sounding less alarmist about the future. But is installing fear is the right strategy? Although the profession of appealing to fear may be the oldest profession in the world.

Summarizing: the present evaluation of 'Climate Change 2007' appears to be of limited usefulness. Minor inaccuracies may be detected. What is really urgently needed, however, is a broader, critical assessment of the work of IPCC and its organization. Pessimists, of course, will be tempted to quote Dorothy Parker: 'Old dogma does not learn new tricks'. One can only hope that critics are not automatically classified as deniers, supporters of the anti-global warming lobby or worse.

[The present comment is based on Drewe, P., Fallacies of global reasoning - more inconvenient truths: ]

2.

Global warming seems to be a case for multiple working hypotheses. 'With this method the danger of parental affection for a favorite theory can be circumvented' (Chamberlin). Parental affection for man-made, CO2-induced global warming explains the uncritical acceptance of any corroborating 'evidence' as in the case of the Himalaya glaciers. Shouldn't one rather look for deviant cases? The time-honored principles of falsifiability and falsification do not seem to hold for the work of IPCC.

1.

The level of policy intervention must correspond to the level of analysis. It is not correct to jump (without a multi-level analysis) from a higher level of analysis to a lower level of conclusion on which the policy intervention is based. This would produce a fallacy of disaggregation. Hence if the problem has been stated and analyzed as one of man-made, CO2-induced climate change at the global level, one cannot simply assume for example that carbon trade can help to solve the problem by allowing cities or regions in developed countries to buy the right to pollute some more which is traded off for environmentally-friendly projects preferably in developing countries. As to the multi-level analysis, countries (leave alone continents or sub-continents) should not be seen as some kind of macro regions which is outright ridiculous for example in the case of China. But even small countries such as the Netherlands are too complex to be treated as one region as one has learned only recently.

The work of IPCC: a comment

The Dutch Planbureau voor de Leefomgeving has been charged with the evaluation of 'Climate Change 2007: Impacts, Adaptation and Vulnerability'. Outsiders have been invited to submit their comment to: . my comment did not comply with the 'rules'. Instead of helping to improve the 2007 report, it is rather a plea for a broader, critical assessment of the work of IPCC. Note that IPCC's auto-assessment is scheduled for 2013 and 2014.
By the way, 40 emails have been received about mistakes in the 2007 report.

The work of IPCC deviates from basic methodological rules. There are three major flaws:

1. Focusing on the global scale does not suffice: a multi-level analysis of environmental problems is called for on macro, meso and micro levels, but - in especial at the meso level of cities and regions.

2. Man-made CO2-induced global warming is basically a one-factor theory which tends to invite simple correlations a la Al Gore.

3. IPCC's handling of uncertainties leaves much to be desired.