The end of the world is at hand
Tony Osman
GLOBAL WARMING by Stephen H. Schneider
Lutterworth Press, £13.95, pp. 343
We had better get it right, and quickly. If there is a Greenhouse Effect, if the gases we produce on earth by combus- tion really are trapping the sun's heat and slowly raising the average temperature on earth, then we have to reduce combustion, and/or find ways of mopping up those gases. We do not have a lot of time because, if the doom-sayers are right, the process cannot be quickly reversed, and there will be serious — very serious — problems within 50 years. Rather a lot of the people who read this review will still be around then.
Of course, if the doom scenario is wrong, then we shall have caused quite unnecessary hardship by 'anti-Greenhouse' action. Industry and transport will have cut their fuel consumption, and the rising tide of domestic energy use will have been reversed, all to no purpose. Quite a few industrialists believe that the Greenhouse Effect offers no threat, and many others, worried about staying profitable in hard times, say that they believe it. And they point to what they claim to be scientific dispute.
It is a subject that demands public understanding because the politicians of the world will have to act and take mea- sures that will reduce the immediate com- fort of life. They will have to restrict the use of fuels that put Greenhouse gases into the atmosphere, force industry to change some of its ways, and perhaps make decisions about land use. If governments are to take these potentially unpopular actions, they need to know that their electorates back them.
This book incontrovertibly shows that the problem is real. Stephen Schneider is probably the world's expert on the subject and he describes just what the evidence is. And he shows why climatologists are cau- tious. Climatology is an awkward scientific subject — you cannot devise a simple experiment to test a theory. And scientists are always cautious about extrapolating from their results: with particularly good reason when the prizes for getting it right, and the penalties for getting it wrong, are so big.
What is certain, as this book shows, is that the temperature on earth is rising. This is a matter of direct measurement using a worldwide network of thermometers, although it is not an easy measurement. But allowing for all possible sources of error, there is a consensus that global tempera- tures have risen by about 0.5°C since the beginning of the century. This may not seem much, but small changes in average temperature are enormously important. The average temperature during the Ice Ages was only 5°C less than today's. And although climatologists are talking of only 0.5°C this century, they are talking of a possible increase of 5°C during the next 50 years.
Is there any evidence that this is a `Greenhouse Warming'? Is the rise certain- ly caused by Greenhouse gases? A basic fact is that the amount of the main Green- house gas, carbon dioxide (CO2), has increased by 25 per cent since the begin- ning of the century. This does not prove cause and effect — the number of rock singers, for example, has also increased dramatically.
The evidence of a link comes, as Schneider tells us, in two forms: ancient very ancient (hundreds of thousands of years): and modern — ultramodern using computer modelling.
The 'ancient evidence' is stunning, both in what it shows, and in what it tells us of the skills of a modern scientist. The Antarctic Ice Cap has accumulated over several hundred thousand years. Trapped in it is air from the time that a particular layer was formed: and the nature of the ice in a layer tells scientists the temperature of the snowfall that formed the layer. The graphs of temperature and CO2 concentra- tion match quite anstonishingly well. As one goes up, so does the other. Ditto down.
The computer evidence is more compli- cated. Climatologists 'model' the atmos- phere: that is, they write computer instruc- tions that represent everything they know — solar heating, polluting gases in the atmosphere, clouds, reflection of sunlight by ice, the effect of the oceans as a heat ballast, the changes in temperature due to water vapour condensing as rain, and so on. They put all these processes on to a supercomputer — they need an exotic machine because there are so many data, so many processes. Then they set their `computer world' to run.
As Schneider says, triumph in modelling gives what seems to be a very modest result. The computer showed that on earth, it would be warm in summer, unsettled in autumn, cooler in winter, and you'd think you didn't need a multimillion- pound computer to work that out. But of course, if their computer could be accurate with a normal (climate) input, it could be trusted to make a forecast about the Greenhouse effect. The machine con- firmed the doomy predictions.
They are doomy. If overall temperature changes, then weather patterns will alter. It isn't a matter of being able to grow wine in Lancashire, so that connoisseurs can sip Château Salford. There is the possibility that the rain-systems that irrigate, say, Colorado and California will move. If the temperature rises, then the seas will ex- pand, as the liquid in a thermometer expands, and will flood low-lying areas such as San Francisco and London Dock- lands. This will also — do we need an also? — damage the agriculture of areas around bays: San Francisco, for example, has to have an elaborate programme that keeps enough fresh water running into its bay to keep the sea out. This would be doubly threatened — by rising seas and reduced river flow.
And then there is the Third World. Millions of people in Indonesia, say, or Bangladesh, live in areas that would be inundated by even a modest rise in sea level. Schneider devotes an early chapter to horror stories that include the possibility of millions of Third Worlders taking to ships, looking for dry refuges. He sees peaceffil solutions with refugees in camps: there is the possibility that the world's underprivileged will get angry and take what they feel is reasonable from the rich, developed countries. We had better accept the 'Greenhouse Scenario' and do some- thing about it.
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