Global warming killing the planet? It’s not fact – just hot air
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INCLUDEPICTURE "http://www.theherald.co.uk/images/space.gif" \* MERGEFORMATINET PROFESSOR MIKE JACKSON December 11 2006
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Think tank: We present you with a radical idea. Then you tell us whether we're right or wrong
Not since wholesale calamity was predicted as a result of the so-called millennium bug has so much coverage been given to a topic. Miles' worth of column inches are now dedicated to global warming. The predictions by media commentators are becoming more numerous and more strident as each new piece of evidence appears to support their case. They have progressed from possibilities to probabilities and are now becoming certainties.
Global warming is a hypothesis, not fact. And even if temperatures are increasing, that does not necessarily mean it is a result of human activities, nor does it mean that the outcomes will necessarily be overwhelmingly detrimental.
That average temperatures have risen over recent decades - globally and here in the UK - is undeniable. The evidence from records is that the hottest years of the last millennium have probably occurred in the past two decades. However, the years from 1800 to 1900 were particularly cold, so the increase in average temperatures from 1800 to 2005 may not really be as significant as it first appears. Also, the temperatures in the upper parts of the atmosphere (the lower stratosphere) appear to have been falling at a faster rate than those at the earth's surface have been increasing, at least since 1960. In addition, the increase in average temperature over much of the land masses appears to be the result of higher night-time temperatures rather than higher day-time temperatures. This is possibly due to increased cloud cover over those land areas.
Although the actual temperature has been higher during the last two decades than at any time since 1800 (with the exception of a few isolated years during the 1940s) there have been periods when the rate of increase of temperature has been at least as great as now. The periods from about 1860 to 1880 and from about 1910 to 1940 show sharp and consistent increases; whereas the periods from about 1880 to 1910 and from about 1940 to 1955 show the opposite. So, over the last one and a half centuries, the average temperatures have fluctuated periodically.
The further back in time we look for records of atmospheric temperatures, the more uncertain the data become. Clues as to what the weather was like at particular times in history are provided by evidence from tree rings, from core samples of ice and from written material, but these must be read with caution. Accurate scientific records are a recent arrival, relative to the time that has elapsed since the last ice age. From such evidence, however, it would seem that, some two millennia ago, parts of the UK were at least as warm as now. There are reports of the Romans growing grapes and of malaria being present in parts of the south-east of England.
The evidence, which is much more comprehensive than that intimated above, needs to be judged with caution. Most scientists working in this field will liberally use such terms as "may", "perhaps" and "appears" rather than "will", "definitely" and "shows" when discussing the significance of their findings, particularly when this applies to predictions about the future. On the other hand, some politicians, some journalists and some who have a vested interest seem intent on talking up the possible occurrence and the worst consequences of an increase in global temperatures.
Many now believe global warming is already an environmental problem; many more believe that it is in the throes of becoming one. Nevertheless, there are still many who remain to be convinced. Nor is this surprising when the record of environmental catastrophe predictions is examined. Caution applies in all walks of life. The only thing we seem able to say about the future with any degree of confidence is that it is unpredictable.
In 1972, a group of scientists known collectively as the Club of Rome predicted the world was using resources at such a rate that most reserves would be exhausted by the end of the century. The data they used certainly supported their case; what was at fault was their ability to predict the future. Take oil as a prime example. The authors confidently predicted that there were only 550 billion barrels of oil reserves, which would be exhausted before the end of the twentieth century. Some six years into the 21st century, we have known reserves of 1200 billion barrels that could last until the end of this century.
Rather than just being wrong, predictions can cause serious problems. In 1962, Rachel Carson wrote her book Silent Spring, which became the foundation for the case against the use of DDT. The case against DDT went something like this: the evidence that DDT can be harmful was incontrovertible; surveys found residues of DDT in the tissues of animals across the globe; a reduction in some bird populations was detected; the eggs of these birds appear to have thinner than normal shells, leading to a failure in reproduction; this must be due to DDT; the use of DDT must stop.
It is now understood that the decision to ban the use of DDT was a mistake. None of the steps in the argument above is wrong; what was wrong was the prediction that the consequences of the continued use of DDT would be worse than those of discontinuing its use. The replacements were less effective and because the control of mosquitoes was less effective so too was the control of the spread of malaria. Malaria is now once again a major killer, particularly of children. The premature decision to ban the use of DDT led to the illness and deaths of perhaps millions of people in the developing world.
Because of serious air pollution, especially by particulates, there was a fear in the 1950s that (ironically as it now seems) we could be heading for a new ice age. This did not happen. By the 1980s, it was acid rain. The worst-scenario proposition was that we would soon have no life in inland waterways because of the acidification of the water by rain, and that forests would die because of the effect of the acid on the trees. This did occur to a limited extent but the term catastrophe is hardly appropriate.
Another fear at this time was the destruction of the ozone layer. It is difficult to say whether the danger here was overstated because action was swift and relatively painless. CFCs in aerosols were replaced by less damaging alternatives and the problem was superseded by the current problem, namely global warming. Those who castigate the USA for the role it plays - or fails to play - in the global warming debate should note that the USA (together with Canada and Scandinavia) was some two decades ahead of the rest of the world in tackling the problem.
The reason why some people are sceptical about the dangers of an environmental disaster from global warming is that in the past, almost without exception, predictions of such disasters have turned out to be wrong. But what about the argument that the potential for disaster is so great that we cannot afford to take the risk? Following that argument, we should take precautions against the worst possible scenario.
To predict how a small rise in temperature will affect the weather decades or even centuries from now presupposes weather-predicting capabilities that we do not at present possess. At the moment we can be reasonably sure of the weather forecast up to about 24 hours ahead. After that the predictions become much more imprecise and much less reliable. Yet the whole basis of the global warming debate on the "pro" side is that the weather is destined to change throughout the world.
The other aspect of these predictions is that such changes will inevitably be detrimental. Why? In the UK it has been suggested that we could expect a Mediterranean-type climate. It is then suggested that many people will die as a result of the stress of the raised temperatures. The people of the Mediterranean area seem to enjoy a long and happy life so why shouldn't we also? In any case, would not the people dying because of the raised temperatures, if any, be more than offset by the much larger numbers who currently die of the cold each winter?
The same arguments can be made about flooding and starvation. These problems might be manifested in areas that currently have no such problems. Are the people proposing these arguments unaware of the millions who are presently affected in this way in other parts of the world? Maybe those presently suffering people will be better placed in the future and who could say they did not deserve their lucky break?
So should we turn our backs, like Luddites, on so much of modern technology? We are being exhorted to cut out flights abroad. The effect on people doing the flying might be a short-term disappointment but the loss of tourism in those countries that would expect to receive the flyers could be devastating.
We are also exhorted to stop buying goods that are transported around the world. Shop locally, we are told. Again, this could be devastating to the economies of many underdeveloped countries to which such income is essential.
We now have the intervention of the noted economist Sir Nicholas Stern. An impressive contribution to the debate, it nevertheless ends up by saying, among other things, that much more work is required from scientists and economists to resolve the uncertainties. In terms of predicting the future, economists probably have a poorer track record than almost any other group.
Should we do nothing for the environment? Certainly not. Conservation of the environment is essential if we are to leave a worthwhile planet for future generations. The halting of deforestation, for instance, is of the utmost importance. We should all economise on the use of resources and energy.
Sir Nicholas Stern advocates the spending of enormous amounts of money to mitigate the worst effects of global warming. But his premise is based on the effects of global warming being so disastrous that almost any price is worth paying to ensure it does not happen. This ignores the fact (not hypothesis) that life is currently awful for a large proportion of the world. Disease, starvation, drought and flooding are realities that many people already live with. If we would invest the sums proposed by Sir Nicholas into, for instance, sub-Saharan Africa, what an effect it would have. The provision of clean, safe water supplies, the elimination of malnutrition, the provision of medicines to prevent childhood death and disease and the provision of education to children who presently receive little or none. Over a few years we could save millions of lives and prevent terrible suffering to many millions more and make communities self-sufficient. Now that would change the world as we know it.
Mike Jackson is emeritus professor of environmental health at the University of Strathclyde and honorary fellow of the faculty of medicine of the University of Edinburgh.
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