Jane Powers on carbon offsets
As we now know, excessive carbon dioxide in the atmosphere is one of the chief causes of climate change. Burning fossil fuels is our greatest carbon-generating activity, making up 75 per cent of the CO2 produced by human beings. Vast amounts of oil, gas, coal and peat are consumed in our part of the world by heating, power and industry. And - of course - by transport, with more frequent and longer-haul air travel widely viewed as a major culprit in accelerating climate change.
Jet engines don't just emit carbon dioxide, they also cause vapour trails to form, which trap heat, so that they produce a warming effect that is 2.7 times greater than that of their CO2 load (according to George Monbiot, in his recent book, Heat).
But just as we were learning these killjoy facts, along came "carbon offsets". If you paid a premium, you could have your cake and eat it, too. Carbon offset schemes work in a number of ways. The best-known involves planting trees to drain excess carbon from the air, thereby creating "carbon sinks". Other projects invest in renewable energy or energy-efficient enterprises, which produce emission savings that cancel out the pollution generated by the activity funding the offsets.
However, some environmentalists believe that the carbon offset mechanism is flawed, for many reasons (see: www.carbontradewatch.org). Poorer countries in the south - where most of the schemes take place - are in danger of becoming a carbon dump for the north, they argue. In the worst cases, people and the environment suffer unfairly. In parts of Brazil, for instance, plantations of alien eucalyptus trees (used for paper pulp) have degraded the landscape and water supplies, and have destroyed the livelihoods of local farmers. The company that owns them is seeking carbon credits through the Kyoto Protocol's Clean Development Mechanism (see: www.sinkswatch.org).
Carbon is sequestered in trees only temporarily, and is released again through various events, including natural decay, felling and forest fires. Forest-planting, therefore, is no more than a short-term solution. Offset schemes, claim those who oppose them, merely prolong our dependence on fossil fuels. Carbon, they say, is best left in the ground, rather than being released into the atmosphere.
On a personal level, it could mean turning down the heating and taking your winter holiday at home with a travel book.