Is global warming the scourge that will kill off our planet or is it a myth?

Ayala Ochert assesses the climate of opinion (left) while Fred Singer argues that we need to collect more scientific evidence before taking drastic action The debate over whether or not the earth is getting hotter is much more than a simple argument over "how much hotter and how soon?" Between those who believe in global warming and those who do not there is little common ground. The Intergovernmental Panel on Climate Change, set up by the United Nations Environment Programme and the World Meteorological Organisation as a world authority on global warming, gives official estimates of how much, how soon, and then attempts to give advice on what action we should take. But from all sides scientists, economists, ethicists and policy-makers challenge the panel's authority. These dissenters shed doubt on the folklore about global warming.

The warmers' thesis seems simple enough: carbon dioxide in the atmosphere warms the earth. This century the earth has warmed, on average, by half a degree. This warming is a result of the increased levels of carbon dioxide in the atmosphere that have accumulated since the beginning of the industrial revolution through the burning of fossil fuels, such as coal. If we continue to allow carbon dioxide emissions at the present rate then the earth will experience even greater warming. This warming will significantly alter the climate, with devastating consequences for future generations. We must do something now to prevent these consequences before it is too late.

But at every level of the warmers'argument there is some degree of dissent. That carbon dioxide in the atmosphere warms the earth is probably the closest thing to a point of agreement. No one doubts, for instance, that there is such a thing as the "greenhouse effect": that the earth's atmosphere, like the glass in a greenhouse, keeps us much warmer than we otherwise would be. The moon, which has no atmosphere, is 33 degrees cooler than we are. But whether carbon dioxide is mainly responsible for this greenhouse effect has been challenged. Some say that carbon dioxide levels might be a side-effect rather than a cause of warming.

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It is hard to imagine at first how scientists could disagree over whether the earth has or has not already warmed. According to most scientists, the 1980s showed the seven hottest years on record, but according to Fred Singer, director of the prestigious United States Science and Environmental Policy Project, there has been no increase since 1979. "What I do take seriously is that there has not been the large increase one would expect. The data simply does not support current theory," he says. Michael Hulme, senior researcher in the Climatic Research Unit at the University of East Anglia, says the reason for this disagreement is simple enough - while Singer has been looking at data from satellites, everyone else has been looking at records of surface temperature. "The satellite measures a layer several kilometres thick, so there is a difference in what is being measured. So, a priori, we expect the data to be different because we are measuring different quantities."

It is freely admitted by the warmers that the recent fluctuation in temperature still lies within the "natural variability" of the climate, but, they argue, the mounting circumstantial evidence that we are the culprits cannot be ignored. Increasingly, climate modellers are looking for "fingerprints" of global warming. As their models become more accurate, they hope to use emerging climate patterns as indicators of the phenomenon.

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The claim that if we continue to allow carbon dioxide emissions at the present rate the earth will experience even greater global warming remained almost uncontested until Jack Barrett, assistant to the head of inorganic chemistry at Imperial College entered the fray. He argues that water is a much more significant component of the atmosphere than is carbon dioxide: it absorbs radiation much more strongly and there is (typically) 50 times more water than carbon dioxide in the atmosphere. Carbon dioxide at low altitudes is already absorbing all the solar radiation there is, so if we put more into the atmosphere it would have no effect. But Barrett's remarks provoked an angry reponse from the scientific community. Tony Sligo, of the Hadley Centre, said Barrett's paper was demonstrably wrong and should never have been published.

While it is nearly impossible to estimate the effect of global warming on the frequency of freak weather conditions, other phenomena such as rising sea levels are easier to evaluate. "Devastating consequences" include the disappearance of some low-lying islands as the rising oceans engulf them. The Alliance of Small Island States made an impassioned plea in Berlin in March, for their future to be taken seriously by the rest of the world. So far a rise of one millimetre per year has been measured and this could go up to six centimetres per decade, say IPCC scientists.

But the dissenters disagree: "The rise in sea levels seems to be independent of global warming. The best thinking might be that it is a lowering of land surface," says Fred Singer.

But where on the scale of "devastation" do the consequences of global warming lie? Michael Hulme thinks that it depends on how you see the future: "There are going to be many other aspects of change that will determine human welfare. Regional conflicts, for instance, might be much more significant. One million Rwandans were killed recently, but no study predicts this much loss of life from global warming."

But one recent estimate has warned of a refugee crisis on a scale never before seen - up to 200 million people. "Here in the United Kingdom, we're in a fairly good position to respond to climate change through improved sea defences and reinvestment in new forms of agriculture. Studies of the impact that this will have on the economy suggest that we will suffer only 1 per cent loss of GNP over 50 years, which would be barely detectable to most of us. Recent changes in eastern Europe, for instance, resulted in a 10 per cent loss over five years. That doesn't mean that it's not important, but I think quality of life will suffer more from low-level pollution," says Hulme.

Manmade climate warming, a phenomenon that may not even exist, has been linked to all sorts of calamities: collapse of the Antarctic ice sheet, worldwide flooding as ocean levels rise, destructive hurricanes, droughts and agricultural disasters, mass starvation, and the spread of tropical diseases that could put three billion people at risk. These calamities are not grounded in fact but spring from the feverish imagination of activists, and their ideological desire to impose controls on energy use and thus throttle economic growth. Growth is "bad" runs their dogma.

To convince the public of the urgent need for a Global Climate Treaty - with international controls on the emission of "greenhouse" gases - the activists have been trumpeting a supposed "scientific consensus". Scientists who disagree are conveniently labelled a "tiny minority" of sceptics - or worse - in an obvious attempt to avoid public debate on the scientific evidence.

To bolster their claim, the warming activists invoke the UN-sponsored Intergovernmental Panel on Climate Change, involving some 300 scientists. The widely-touted IPCC report itself, however, as opposed to the policy- makers' summary prepared by the panel's leadership, shows considerable scepticism about the current reality of greenhouse warming. The foreword to the 1990 IPCC report admits to dissenting views that "could not be accommodated" by the editors. Evidently, "consensus" is arrived at by disregarding the many scientists who disagree.

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The statesmen who adopted the Framework Convention for Climate Change at the 1992 Earth Summit in Rio de Janeiro were led to accept three propositions - all of them false: There will be a major warming soon; it will be catastrophic for the world; something can and should be done to stop it. At Rio there surfaced the "Heidelberg Appeal", a statement eventually signed by more than 4,000 scientists, among them some 70 Nobel laureates, vainly imploring the policy-makers not to give in to panic, and to use sound science.

The key assumption behind the framework convention is that the climate warming predictions of general circulation models can be relied on. The predictions of these models differ widely, however, with average global temperature increases from 1.5 to 4.5 degrees centigrade for an assumed doubling of atmospheric greenhouse gases by the middle of the next century. But how do we know whether these published IPCC predictions are valid? "Validation" of models means comparing calculations based on theory with the real atmosphere, specifically with the temperature record of the last 50 to 100 years. The IPCC policy-makers' summary asserts that theory and observations are "broadly consistent". But according to published surveys, the majority of IPCC scientists do not buy this claim. The discrepancy becomes quite clear also from the body of the 1990 report itself.

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Nevertheless, "broadly consistent" has become the mantra of those pushing to control the emission of carbon dioxide from fuel burning by curtailing energy use. This artfully worded phrase covers up the fact that the models have failed miserably in accounting for past temperature changes, cannot explain the highly accurate global record from weather satellites - and are internally inconsistent to boot. Depending on how the models are constructed, their predictions of future global warming vary by 300 per cent and even more regionally.

There is no evidence as yet that manmade warming is taking place in spite of the continuing increase in the atmospheric concentration of carbon dioxide and other greenhouse gases. As is widely recognized from global climate data, a major temperature increase - evidently a natural fluctuation - occurred before 1940. Since then, there may have been a slight warming or even a slight cooling, depending on which data compilation one accepts, but nothing like the temperature increase predicted from theory. Certainly, the high-quality global data from weather satellites, available since 1979, show no warming whatsoever - in no way "broadly consistent" with the "best" IPCC-predicted increase of 0.3 degrees centigrade per decade. As time passes and contrary data accumulates, more scientists are becoming openly sceptical about a major global warming in the next century. I confidently predict that the IPCC will be forced to lower its temperature predictions to match the observations.

The science basis for climate warming has come under attack also in the world's leading scientific journals. An editorial in Nature (September 22, 1994) chastises IPCC leaders for supporting recommendations for deep cuts in the emission of carbon dioxide with little more than press releases and executive summaries - "euphemisms for sound-bites directed at those who do not read".

In an article in Science (September 9, 1994) reporter Richard Kerr reveals the "fudging" that modellers engage in to make the models come up with the "correct" numbers. For a model to predict future climate with any credibility, it must first be able to reproduce the current climate. But to do this, Kerr reports, "nearly everybody cheats a little". Some do this by "adjusting" the transfer of energy between ocean and atmosphere. Others "tune" their models by changing the strength of the solar radiation until they get just the right answer.

Still, most atmospheric scientists do expect a modest average warming in the next century as greenhouse gases accumulate in the atmosphere. Many experts believe that it will be barely detectable, leading merely to higher night-time and winter temperatures, with consequences that are on the whole beneficial, especially for agriculture: Increased atmospheric carbon dioxide, which stimulates more rapid plant growth; increased ocean evaporation and rainfall, leading to more (rather than less) soil moisture; and, of course, a longer growing season and fewer frosts. Not for nothing is the temperature "high" around 1000 ad referred to as the "medieval climate optimum". We should be afraid of climate cooling.

Of course, none of this will ever make the front page. Environmental activists, politicians, and bureaucrats will continue on their merry way - trying to curtail the use of energy, imposing huge financial burdens on consumers, and upsetting national economies - all in utter disregard of the underlying science.

The Global Climate Treaty's ultimate objective is stabilisation of greenhouse gas concentration in the atmosphere. This is not, as some might imagine, the same as stabilisation of global emissions - which would be a less daunting goal. Even if achievable on a global scale, keeping emission rates level would merely reduce somewhat the rate of increase of the concentration and delay a doubling of greenhouse gases by only a few years.

No. A careful reading of the IPCC report makes it clear: To avoid a further increase in the concentration of carbon dioxide requires an emission reduction - globally - of 60 to 80 per cent. And that translates into a reduction of energy use from fossil fuels by about the same amount.

In light of these more sober appraisals we need to re-examine the goal of greenhouse-gas stabilisation: its need, timing and feasibility. The need is rapidly disappearing in the light of better science. The timing can safely be delayed by a decade or more, as can be readily discerned from the published IPCC analyses. By then we will also have 25 years' worth of satellite data and perhaps a better scientific understanding of what's wrong with the theory.

But it is the feasibility that should concern the Earth Summit politicians. How on earth can one reconcile economic development - the other aim of the UN Conference on Environment and Development - with cutting back on energy use in the less developed nations? It is hard to believe that the statesmen at the Rio Earth Summit were blind to this obvious contradiction. Researching the speeches delivered there, I found the conflict addressed only with platitudes about "sustainable development". When the "N-word" was mentioned at all, it was only to attack nuclear power (which emits no greenhouse gases).

What to do? Beyond continuing climate research, one should take all the prudent steps that make sense even without the global warming scare: practising energy conservation, increasing energy and resource use efficiency, increasing forest mass by reduced cutting and more planting of trees, and - dare we mention it - encouraging nuclear energy. These were the steps that geophysicist Roger Revelle, father of greenhouse warming, recommended in a 1991 article in the journal Cosmos, written shortly before his death. He also recommended that we look before we leap. It is still good advice.

S. Fred Singer, an atmospheric physicist, directs the Fairfax, Virginia-based Science & Environmental Policy Project.

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