Ragnar Lofstedt fears that action on global warming will only start when the economic consequences begin to bite

Global warming is one of the most controversial environmental topics - largely because of the uncertainty surrounding it. Some researchers say that the world is becoming warmer and urgent action is needed to reduce emissions of carbon dioxide (the main culprit of global warming). Others, like environmental economist William Nordhaus at Yale University, counter that the evidence is far from proven, and that it would be more prudent to adopt a "wait and see" approach.

The main impetus for action comes from the Intergovernmental Panel on Climate Change, founded in 1988 under the chairmanship of Bert Bolin of Stockholm University, by the World Meteorological Organisation and the United Nations Environment Programme. The IPCC consists of three working groups. The first, led by Sir John Houghton of the United Kingdom Meteorological Office, is concerned with scientific assessment of global warming; the second with the potential impact of global warming (such as the rise of sea levels) and the third looks at ways we might respond to global warming's risk, including, for instance, carbon dioxide taxes on petrol.

Of the three groups, the one that has received the most international recognition is Houghton's, which has produced data showing the average global air temperature has increased by by 0.3-0.6xC over the last century. The group has further predicted that a doubling of carbon dioxide emissions will lead to an increase in global air temperatures of somewhere between 1.5 and 4.5 degrees.

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So far the working group has published two reports: the first, in June 1990, was heralded as the definitive work on climate change. But as it painted a bleak scenario about the likelihood of temperature rises unless urgent action was taken; it was seen as too radical by some researchers. The second report, two years later, partially distanced itself from the hard-hitting findings of the first. Instead of stating categorically that the world will definitely enter a period of global warming unless there are reductions in carbon dioxide emissions, it hedged around the issue, admitting to a high degree of uncertainty in predicting when warming will occur. Two of the second report's findings were particularly interesting - that chlorofluorocarbons, refrigerator and aerosol propellants, should no longer be considered a major greenhouse gas, and that aerosols produced by sulphur emissions may have already offset much of the global warming in the northern hemisphere.

This second report was interpreted by some scientists as a climbdown. They surmised that in the future IPCC's work might be seen as less authoritative by policy-makers. Some national policy- makers, especially those from countries which have a vested interest in not seeing imposed reductions on the use of fossil fuels, took the second report as an endorsement of the "wait and see" approach to global warming. They argue that improved scientific procedures will provide evidence to diminish the uncertainty surrounding global warming and the worst case scenario will not be so bad after all.

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At April's UN convention on climate change in Berlin representatives of high fossil fuel consuming nations argued that it would be prudent to wait until the next IPCC report is published before any commitments to further carbon dioxide abatement measures are made. However, Bolin has warned that stringent abatement measures should not be postponed because research in the forthcoming 1995 IPCC update report suggests that the evidence for global warming is growing. The report (due to be published at the end of this year) will indicate that, over the past few years, global mean annual temperatures and the rise in natural disasters as a result of global warming have all followed the trends predicted in previous reports.

Among the more interesting findings in the forthcoming report are that droughts in southern parts of Africa over the past ten years fit almost exactly with earlier predictions. And for the first time IPCC researchers are sure past temperature rises were caused by human activity (burning of fossil fuels and so on) rather than by natural fluctuations and that these rises are highly likely to continue.

These findings suggest that the IPCC's earliest set of predictions are being borne out. If the trends continue the scientific uncertainty surrounding global warming will be reduced, to be replaced by the reality that the world is entering a period of global warming. But it is unlikely that we will see greater enthusiasm about cutting carbon dioxide emissions worldwide as a result. The policy-makers time frames mean that the problems outlined in the new report are happening too slowly. If the world does not become perceptibly hotter due to global warming within the lifetime of a government, the political will for action is limited. It will take decades, if not centuries, before anything like the major climate changes predicted to occur actually happen - such phenomena as melting polar ice-caps, large rises in sea levels, or scorching temperatures in parts of the world. Hence, as only large insurance firms, environmental NGOs and some Green parties are concerned about the current trends, the more likely environmental policy outcome of the forthcoming IPCC report will be that more money is forthcoming for research into the speed of the changes and more international meetings are convened to debate the outcomes.

Only when the economic impacts of the effects of global warming are felt, with insurance companies having to pay ever increasing sums for climate disasters, are we likely to see more convincing climate policies.

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Ragnar Lofstedt is based at the centre for environmental strategy, University of Surrey.