DR JOHN Mitchell of the Hadley Centre for Climate Prediction and Research uses computers to simulate the atmospheric processes that may lead to global warming. His, indeed, is one of the most authoritative voices on such matters in these islands.
It was a pleasure, therefore, to hear him speak at TCDon Monday evening and he concluded his lecture by presenting a list of the seven most popular misconceptions about climate change and global warming. Here they are:
. That the greenhouse effect began in 1980. Dr Mitchell points out that the greenhouse effect began about three billion years ago, and made life possible on Earth; the problem as far as global warming is concerned is an enhanced greenhouse effect, a relatively recent phenomenon brought about by man made interference, albeit inadvertent with the atmospheric chemistry.
. That by 2050 the world will be 4 or 5C warmer, than at present the relatively simple computer simulations of a decade or so ago produced figures of this kind, but the more sophisticated models of today suggest an average rise in global temperature of 1 to 1.5 in such a time scale - significant, but by no means catastrophic.
. That the rise in temperature will be steady and consistent. The indications are that if global warming does occur, it will tend to be erratic; some years may be much warmer than at present, but others not as warm, and only in the aggregate might a gradual upward trend become apparent.
. That Ireland and Britain will acquire the climate of the south of France: No one knows as yet; it is tempting to plump for the effect of a simple shift in latitude, but the reality is likely to be very much more complex.
. That summer rainfall will decrease: No such conclusion can be drawn from the output of the models - indeed, some suggest the opposite - but with more effective evaporation in the warmer summers, the droughts so often talked about may well occur.
. That our climate will be more extreme: While warmer summers are predicted, there are no indications our winters will be colder.
. And finally, that the level of the sea will rise by several metres. All the indications are that the rise in sea level by the second half of the next century might be 20 to 25 centimetres, or about a foot - significant enough in vulnerable spots, as Dr Mitchell says, but hardly Armageddon.