Hotting up

Discussions about global warming seem to be based on everything but science, explains Peter Sammonds

So what is going on with global warming? First there is the question of whether global warming is occurring - which, on balance, it probably is. The harder and more interesting question is, what are likely to be the consequences?

Away from the horrifying headlines and campaigns of environmental pressure groups, it is instructive to examine how global warming is being seen by business - in particular, by the insurance industry. Insurance is all about statistics and quantifying loss, and a common theme of environmentalists is that we cannot chance the future of the planet. But it is quite possible to insure yourself against what are perceived to be the hazards arising from global warming.

This is the insurance industry operating at its best: sell insurance against a risk, make sure the risk is small, make lots of money. The insurance industry's dispassionate view is that global warming is probably occurring and certain related natural hazards, such as floods and hurricanes, could increase in frequency, at least regionally. But while insurers do expect to be paying out ever-larger sums against these hazards, any increase due to an increase in hurricane frequency, say, is only a small factor. Much more important to insurers is that, as society gets richer and the population grows, there are more buildings, each of more capital worth, that could potentially be damaged. There is currently more money around to pay insurance premiums and more people than ever before are insured. So insurers see global warming as a money-spinner.

But while the insurance industry is taking a sanguine view of global warming, an intellectual vacuum is forming in the scientific debate into which all sorts of ideas about extreme climate events are being sucked. Dennis Avery's argument that the global climate was much better for humankind when global temperatures were 1-2 °C warmer, in what is known as the Little Climate Optimum (900 to 1300 AD), is unanswerable. It is also clear that the global climate was better still in the Holocene Optimum 10 000 years ago, when global temperatures were even higher. So the argument has shifted to the effects of rapid climate change, with warnings about the extreme climate events and inherent uncertainty that could result.

Underlying concerns over rapid climate change is the unsupported supposition that climate itself is chaotic, and that extreme climate events can be triggered by only small, if sudden changes. If climate is chaotic, there are potentially an infinite number of triggers for extreme climate events. Our own chief scientific adviser to the Cabinet, Sir Robert May, believes that Britain can be plunged into an ice age, even as the global atmosphere warms up, because of instability of the ocean circulation in the north Atlantic. Another suggestion, which has also reached the British press, is that an excess in salt water flowing out through the Strait of Gibraltar could trigger a new ice age. Yet some of these postulated mechanisms are blatantly inconsistent with what is already known about climate dynamics and fluid dynamics. For example, if global warming could lead to an ice age (global cooling), our present climate should also be unstable.

You might expect that if global warming were such a threat, there would be a Manhattan A-bomb scale project to find out what is happening and to collect the hard data. However, the budget of the Natural Environment Research Council (NERC), the leading environmental research organisation in Britain, is being increased by less than one percent per annum in real terms. NERC is even considering cutting the number of research studentships it funds - the lifeblood of research in university departments and the source of the next generation of environmental scientists. The Arctic is rightly seen as the bellwether for climate change and of particular importance for Britain. But NERC has only allocated a total of £1.8 million through its new ARCICE programme to fund all Arctic research projects over the next three years. This is a pathetic amount of money for measuring climate change, modelling its impact and making predictions for the future.

So there is something of a paradox. Climate change is proclaimed by the government to be top of its agenda. Its chief scientific adviser has gone out of his way to stress the dangers, the government is always ahead of the pack at international meetings pushing for tighter controls on emissions of greenhouse gases, and even the Foreign Office has got in on the act, with the announcement of a green foreign policy. On the domestic front, global warming is cited as one of the principal reasons for clamping down on car use, taxing lorries off the road and cutting the road-building programme. Global warming is the issue that has put environmental education at the core of schools' national curriculum.

But when it actually comes to monitoring climate change, or modelling its effects, no significant priority is attached to it. And I am afraid I believe cash talks.

The answer to this paradox can only be that science has become irrelevant to government policy and the broader social debate. It is assumed that we know all we need to know scientifically: that global warming is happening; that it is dangerous; that we need to cut back and do less; that we must limit population growth; and that the precautionary principle must be paramount.

Yet the fact is that we do not know how to predict future climate. What we do know is that climate change is the norm and that past temperatures, measured by proxy methods in ice cores and marine sediments, have far exceeded recent measured temperatures.

At a meeting on 'Climate change and health' at the Royal Society in late 1998, attendees discussed the 'growing concern and also controversy over the likely impact of climate change on a range of health problems' (and I thought British pensioners headed to winter time-shares in warmer southern climates to escape hypothermia, flu and arthritis pains). Closer inspection, however, revealed the aim of the meeting: to 'bring together natural and social scientists, the business community, policymakers, journalists and the general public to discuss the effects that possible changes in climate may have on human health'. Are we talking science? In this sense, the debate about global warming is over.

Peter Sammonds is a Royal Society university research fellow at University College London