The Great Carbon Con: Can Offsetting Really Help Save the Planet?

It all started with Sting, this fad for owning one's very own patch of tropical rainforest, though it is probably unfair to blame him entirely for creating the boom industry that buying up forests piecemeal has become. It is 20 years since the musician first set foot in Brazil and pledged to fight the cause of the Yanomami Indians, setting up the Rainforest Foundation to protect forests and their indigenous inhabitants.

Today, protecting forests has acquired a more international purpose. Climate change, rather than assuring the livelihoods of local people, has become the issue. Celebrities and politicians, and many others just in search of a quick buck, are falling over each other to advocate plant-a-tree conservationism as a salve to global warming. Sienna Miller, Tony Blair, Josh Hartnett, Desmond Tutu and Prince Charles all endorse Global Cool, an initiative that encourages individuals to reduce their carbon emissions by, among other things, buying a "tonne of cool."

David Cameron has proudly owned up to offsetting any flights he takes by making a donation to Climate Care, which calculates the cost of the carbon your flight has pumped out and does good stuff, like planting trees, to right the wrong. Sir David Attenborough is a patron of the World Land Trust, which is currently offering to "save a whole acre in perpetuity", for just £50.

However, critics say that there can be no ultimate guarantee of the future of any piece of land. The wealthy financier Johan Eliasch, who advises Gordon Brown on deforestation and green energy, provoked the ire of the Brazilian government with his purchase, in 2006, of 400,000 acres of Amazon rainforest. "The Amazon is not for sale," said the Brazilian President, Lula da Silva.

Eliasch then joined forces with Frank Field MP, and launched a grand tree-buying plan called Cool Earth late last year. Cool Earth stresses that it "leases" rather than buys land, to keep it safe from eager logging companies. Its website explains that saving one acre of endangered rainforest keeps 260 tonnes of carbon safely "locked up" within the forest itself, unable to escape and pollute the atmosphere.

Whoever owns the land or the trees, this method of "capturing" or "locking" carbon into forests is not going to have the knock-on effect of saving the planet. Cool Earth does not claim explicitly to be in the offsetting game, but the carbon that it claims can be "locked up" in one acre of forest would offset 30 round-trips to Rio de Janeiro, say.

For the environmental groups Greenpeace and Friends of the Earth, this forestry offsetting craze is acting as a smokescreen, and detracting from real solutions to escalating emissions."Taking a dodgy accounting proposition, which is that you can somehow identify the amount of carbon that any given new bit of forest picks up out of the atmosphere and sequesters, and make that correspond somehow to emissions elsewhere," is how Greenpeace sees carbon offsetting, according to its senior climate adviser Charlie Kronick. "It can't be done. The methodology is poor, and the logic isn't very good either. Once the carbon you've put in from fossil fuels is up there, nothing is going to make it go away."

Friends of the Earth's Marie Reynolds points out that not only is offsetting no substitute for real emissions cuts, but there is no guarantee, when you plant a tree, what the future of that tree will be. Robin Oakley, Greenpeace's climate and energy campaigner, agrees: "The issue with offsetting is that, fundamentally, it doesn't undo the damage done by carbon pollution. The vast number of players in the offsetting market are not reducing emissions in any accountable or measurable way."

In some cases, local people, far from benefiting, suffer when huge new plantations spring up. Survival International campaigner David Hill says: "Numerous reports show how indigenous peoples have suffered as a result of carbon projects: invasion of their land, evictions, the destruction of villages and crops, reduced access to or destruction of traditional resources, and violent conflict."