To most of the media, and even some senior scientists, the debate about global warming is over. It has been clearly established to their satisfaction by the intergovernmental panel on climate change (IPCC) that the world is heating at an alarming rate and that the main cause is the rise in man-made greenhouse gases, primarily CO₂. We must therefore act now, the argument goes, to implement the Kyoto protocol and follow it up in 2012 with much more drastic cuts in CO^₂ emissions when Kyoto stage one comes to an end. By 2050, emissions must be reduced to a level 60 per cent below those of 1990. Scientific evidence to support these views is claimed to be as strong as that for the link between smoking and cancer, or HIV and Aids, and the only sceptics left are lobbyists for the oil industry. Indeed, Greenpeace and Friends of the Earth criticise the media for continuing to report the views of sceptics, because they undermine public acceptance of drastic measures to save our planet. (The same NGOs happily ignore the views of the overwhelming majority of plant geneticists, biochemists and molecular biologists who endorse the use and safety of genetically modified crops.)

However, the Bush administration and lobbyists for the oil industry are not the only Kyoto sceptics. In 2004, a conference of some of the world’s leading economists, including several Nobel laureates, published what is now known as the Copenhagen consensus. In their list of priorities for dealing with ten big global crises, abatement of global warming was ranked behind action to deal with Aids, malnutrition, trade liberalisation, malaria and access to clean drinking water, among other problems in the least developed countries. In fact, Kyoto came one from bottom of the list. Their report was widely condemned by environmentalists, as was the outcome of the recent G8 summit, because it did not endorse Kyoto in sufficiently ringing terms. Now the economics committee of the House of Lords, advised by the respected environmental economist David Pearce, has published a report, “The Economics of Climate Change,” which not only adds its own weighty criticisms of Kyoto, but also questions the objectivity of the IPCC and accuses it of allowing political considerations to influence some of its findings.

The charge of political bias cannot reasonably be made against the IPCC scientists responsible for the technical analysis of climate change. Their report takes care to mention not only the uncertainties and gaps in current knowledge, but developments that seem to contradict the general trend. A good example of the latter is their treatment of the rise in sea levels, which is widely considered to be the most serious consequence of global warming. To the public, some of the clearest evidence of rapid warming is the melting of glaciers. Who can fail to be impressed by dramatic pictures of massive sheets of ice in the West Antarctic peninsula collapsing into the sea? But the scientists point out that while most glaciers are retreating, some are advancing, and that the Antarctic continent, where the overwhelming mass of the world’s ice is found, is actually cooling and its ice thickening, with a small negative effect on sea levels. Overall, sea levels are forecast to rise within a range of 0.11 to 0.77 metres in the next 100 years, which could have a serious impact on low-lying coastal regions, but is not perhaps the catastrophic rise predicted in some alarmist scenarios. It will mainly be caused by thermal expansion of the oceans. Melting of the ice sheets is “expected to make only a small net contribution in coming decades.” In fact, the IPCC found no acceleration of the rate of sea level rise during the last century, and has lowered its forecast for the present century since its last report because scientists now see a smaller contribution from melting glaciers and ice sheets.

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