COLLOQUIUMS or should one say colloquia? are all the rage in scientific circles nowadays. As I understand it, the idea is that instead of inviting one person to deliver a lecture or a given topic, two or more, perhaps of opposing views, are presented to an audience, and sequentially they "cologuate" or speak together in the same place, thereby providing the makings of a brisk discussion. If you would like to experience a colloguium first hand, you may wish to come this evening to the John Joly Lecture Theatre, in the Hamilton Building, TCD.
The John Joly Colloguium 1996 will concentrate on climate change. There are two invited experts, each with his own perspective on the subject one looks back into the very distant past, while the other uses the computer like a crystal ball, to gain an insight into the climate of the coming centuries.
Dr Peter Coxon of the Department of Geography, TCD, has called his contribution "Climate Change The Evidence From The Past 2.5 Million Years". We know that over the millennia there have been dramatic and sometimes very rapid changes in the earth's climate, as it swings from relatively benign conditions, such as we enjoy at present, to the much colder and severe interludes that we call "ice ages". There are many causes, the most obvious being variations in terrestrial volcanic activity, and also changes in the planet's orbit and orientation relative to the sun. It is chilling in more ways than one to realise that in the past 750,000 years the global climate has been in the "ice age" mode for more than 90 per cent of the time.
Dr Coxon will tell us what inferences for the future can be drawn from this pattern in the past. Dr J. F. Mitchell, on the other hand, takes the present climate as his starting point, and proceeds by a reful calculation to the end of the next century. He comes to us from the Hadley Centre for Climate Prediction and Research in Britain, and his topic is "Modelling Past and Future Climate Change".
The Hadley Centre uses computers and a GCM, or General Circulation Model, to simulate the average long term behaviour of the atmosphere. The Hadley Centre GCM has recently had great success in mirroring the behaviour of the global climate from around 1860 when instrumental records first became generally available to the present day, and this adds to the plausibility of its predictions for the coming century. If you would like to find out what they are, call in to the colloquium at 5.30 p.m. today.