CLIMATE CHANGE: can it be stopped?

• Author: Gray, Vincent

Vincent Gray questions the current preoccupation with global warming.

Benjamin Franklin wrote `in this world nothing can be said to be certain, except death and taxes'. Perhaps we should add a third certainty: climate change. Despite this certainty, we are currently being subjected to a continual campaign suggesting that climate change is unusual, always harmful, invariably caused by humans, and must be stopped at all costs. But can it?

The Earth's climate has always changed, on all time scales. Four and a half billion years ago we started off with an atmosphere of water vapour, hydrogen, hydrogen chloride, carbon monoxide, carbon dioxide and nitrogen. It was mainly the influence of living organisms, notably the plants, that slowly transformed this mixture into the current composition of mainly nitrogen and oxygen that so suits us animals.

The most important part of this transformation was the conversion of much of carbon dioxide into oxygen by abundant plant life, particularly during the Carboniferous age, when most of our coal and oil deposits were formed.

Besides atmospheric changes, the Earth has undergone many temperature fluctuations. The cold periods in the more recent epoch (million years or so) are recognised as ice ages. Amongst the causes are changes in the Earth's orbit, changes in the sun, and drifting of the continents. We are currently awaiting the possible beginning of the next ice age.

It has long been understood that the current surface temperatures on the Earth are higher than they would otherwise be because of the so-called `greenhouse gases' which trap part of the infra-red radiation from the Earth. The most important of these is water vapour, which contributes 60-70 per cent of the effect, but a significant minor contributor is carbon dioxide.

The Swedish chemist Svante Arrhenius in 1896 drew attention to the possibility that increasing carbon dioxide in the atmosphere by combustion of fossil fuels would raise the average temperature of the Earth. His warning went unheeded, as the global temperature fell for the next 15 years, and then there were two world wars and an economic crisis to occupy the world, so that a modest temperature rise went unnoticed. From 1940 to 1976, global temperatures fell and we were told that the new ice age was imminent.

The current interest in the greenhouse effect began in 1988 with a heat wave in New York. For the first time there were accurate measurements of atmospheric carbon dioxide...