Sir - Two separate articles in Science Today (The Irish Times, June 19th) illustrate the complexities of climate change. Dr William Reville correctly highlights the problems involved in constructing computer models of sufficient power for decision-makers to be able to take appropriate action. As he says, the deficit is largely institutional. No international body has the resources necessary to set up and run models capable of persuading vested interests that there is an immediate need for us to change our behaviour.
The bad news is that one of the world's biggest current models is already saying that we do not have 30 to 40 years left in which to make up our minds. Business as usual for another 30 years means that we will have no climate left to worry about. The problem is that there is insufficient consensus that this model is the most accurate one.
Information is also the problem regarding forestry as a potential solution. While the Kyoto Protocol allows forestry as an offset to emissions, this provision is being seen as increasingly chimerical, once full accounting of greenhouse gases and energy inputs is considered.
It is important, therefore, to get the facts right. The EU is in the process of preparing a directive requiring cars to emit no more than 120 grammes of COs per kilometre. Currently, the average figure for new cars is 189 g per km. This means that the figure for the amount of mileage that a tree can offset, under the very best of conditions, is nearer to 50 km per year, as opposed to the figure of 18,300 km quoted from Coford. There is a substantial difference in these figures, roughly equivalent to the difference between a single tree and a whole acre of them. Offsetting all the car mileage in Ireland would mean smothering the entire landscape in industrialised Sitka spruce. Neither an attractive nor a feasible proposition.
With all due respect to your headline writers, it is not forestry which holds the key to global warming, but proper science, adequately resourced and researched, and much greater public awareness of both the nature of the threat and the measures required to avert it - Yours, etc.,
Patrick Finnegan, Climate Change Policy Co-ordinator, Earthwatch/Friends of the Earth Ireland, Upper Camden Street, Dublin 2.