On Climate Change
by P. E. Hodgson
When I first became interested in the applications of nuclear physics I was most concerned by the coming shortage of energy. Since then it has become clear that this is not the main problem. There is plenty of energy for the next few hundred years: enormous deposits of coal, substantial amounts of oil and natural gas, and the likelihood of increasing contributions from nuclear power.
The main concern is now the effects on the world’s climate from the pollution of the atmosphere from fossil fuel power stations. It will be many decades before fossil fuel power stations can be replaced by non-polluting sources such as nuclear and renewable energy, and all that time the pollution will increase. Detailed studies by the Intergovernmental Panel for Climate Change show that the amount of carbon dioxide in the atmosphere is inexorably increasing and the evidence for its effects on the climate is steadily becoming more convincing. In addition, the predicted rise in sea level will have catastrophic effects on low-lying countries.
It is now becoming clearer that the principal danger is not the effects of gradual changes in the climate but the possibility of rapid and irreversible changes. We tend to think of the earth and its climate as a reliable and generally stable system where the weather remains more or less the same when averaged over long periods. There is now increasing evidence that this may not be true, that there is a distinct possibility of large, unexpected, and irreversible changes that quite rapidly have catastrophic consequences.
The study of climate changes is fraught with serious difficulties. Since time immemorial the weather has fluctuated unpredictably, with cold and hot periods, heavy rainfall and droughts, hurricanes, and earthquakes. How can the changes due to man’s activities be distinguished from these natural changes? It is notoriously difficult to establish the presence of a new trend in a fluctuating quantity, and the difficulty is compounded when the fluctuations are on several different timescales, as is the case for climate. There are changes from year to year and ice ages on a much longer timescale. If a trend over a few decades is established, how do we know whether it is soon to be reversed by a major change acting on a longer timescale? more

