Madam, - Richard Waghorne (December 15th) seeks to cast doubt on the projections for global warming by counterpointing the predictions of the 1970s that the world was, in fact, headed for global cooling in the form of another Ice Age.
What Mr Waghorne seems not to realise is that climate change occurs over many timescales. The Ice Ages have recurred at intervals of a few hundred million years; indeed, from the perspective of geological time, we are in an Ice Age at present, though our modern climate represents a very short warm period (as in tens of thousands of years) between glacial advances. The climate change resulting from elevated levels of CO
We might note, in passing, that the projected warming of the atmosphere due to increased levels of CO
I note that Mr Waghorne writes as a representative of the "Freedom Institute". Science's freedom to construct its theories is necessarily constrained by the need for those theories to relate to observable fact.
Some of the facts relevant to this discussion are laid out in the World Meteorological Organisation statement on the "Status of the Global Climate in 2004", issued just last week. This preliminary statement identifies 2004 as the fourth warmest year in the temperatures record (since 1861); indeed, of the 10 warmest years on record, nine have occurred in the past decade.
Over the 20th century the global surface temperature increased by more than 0.6
The predictions of climate models are checked constantly against these observed facts; a model which can accurately describe what has happened in the past is likely to be a good guide to what will happen in the future. It is these models, as regularly reviewed and summarised in the reports of the Intergovernmental Panel on Climate Change, which have informed the Kyoto Treaty.
Far from being "shaky science", the reports of the IPCC are a most solid edifice, representing as they do a broad and deep consensus among climate scientists. - Yours, etc.,
GERALD FLEMING,
Met Éireann,
Glasnevin Hill,
Dublin 9.