Forests may change from friend into foe
Copyright 2000, The Times (London)
November 25, 2000
By Vanora Bennett
EVEN before global warming melts the polar icecaps and turns deserts to jungles, the world of environment activism seems to be turning upside down.
This week, at fraught negotiations at The Hague over how to limit climate change, it has been the people usually labelled environmental baddies - representatives of the United States government and big businesses - who want to go out and plant trees and the green-minded tree-huggers, who usually want to save forests, who now reject the notion that trees can save the planet.
Under the apparently reversed attitudes lies a piece of arithmetic that business and environmentalists have never solved: how bad for the environment is the carbon gases given off by our burning of fossil fuels, and how much must industry cut its use of fossil fuel to limit environmental damage and climbing temperatures?
Three years ago in Kyoto, Japan, the 150-plus countries represented at The Hague agreed in principle to make modest cuts in carbon emissions over the next two decades. Now they are trying to work out how. America, the biggest polluter, wants more choices. In particular, America likes a part of the Kyoto deal known as the "clean development mechanism".
It wants to be able to buy other countries' emission credits; it also wants credits, which can be counted against its pollution levels, both for planting forests and protecting existing ones (forests are known in eco-jargon as "carbon sinks", since trees soak up harmful carbon dioxide). All this would mean less work need be done on reducing domestic pollution levels - vital if the US is to get sceptical farm and factory owners to implement the plan, not to mention get it ratified by a still more sceptical legislature.
Yet sensible and appealing though it might seem to combine more market economics with more forests, the science is hazy. It is relatively easy to know how much carbon there is in a single tree, but it is harder to measure how much carbon there is in a forest or a continent and harder still to work out how much could theoretically be locked up if there were extra forests to do the job.
Research published last month in Nature suggested yet more uncertainties. While planting a forest in theory cools the atmosphere by storing carbon dioxide, other climatic effects of changing the amount of forest cover (for instance, new forests would make the Earth's surface less reflective, so that more sun was soaked up) might wipe out any benefit.
As the Earth warms up, too, carbon stored in soil and vegetation may begin to behave differently; another recent paper by the Hadley Centre for Climate Research suggests that, unless present trends change, forests could by mid century have started giving off the carbon they now store - becoming part of the problem, not part of the solution.
The equation on the table at The Hague has too many unknowns. If a country claims credit not for planting a forest, but for protecting an existing one, how can that contribution be measured, since a mature forest does not lock up any extra carbon?
Sooner or later the countries that signed up to Kyoto will have to concentrate not on forests abroad but on factories at home. America's wish to use existing and new carbon sinks - a cheap option that may buy it time to develop new technologies to reduce the dependency of its industries on fossil fuel - can be no more than a temporary measure. In the long run, there will be no way for the US and its allies to avoid tackling the arithmetic of pollution cutting that Europe wants to face now.
Weighty though the ecological issues are, it is politics and not carbon that has lent intensity to this week's debate.