It's one of the most fashionable ideas to save the planet from global warming: buying up tropical rainforest to save it from destruction. Gordon Brown has even appointed the millionaire founder of one such charity, Johan Eliasch, as his special adviser on deforestation.
But like all big ideas it is controversial, and this week a leading Amazonian campaigner will visit Britain to protest that this latest trend is linked to a health and social crisis among indigenous people, including sickness, depression, suicide, obesity and drug addiction.
Davi Kopenawa, a shaman of the Yanomami tribe, will help launch a report that, says Survival International, the charity behind it, claims separation from the land is directly linked to the 'physical and mental breakdown' of indigenous communities, whose lifestyle and culture is already under threat from mining, logging and resettlement away from traditional lands.
In a statement issued through the group, Kopenawa said: 'You napepe (whites) talk about what you call development and tell us to become the same as you. But we know that this brings only disease and death. Now you want to buy pieces of rainforest, or to plant biofuels. These are useless. The forest cannot be bought; it is our life and we have always protected it. Without the forest, there is only sickness.'
Survival International, which announced Kopenawa's visit, said that destruction of the rainforest had been blamed for the release of 18-25 per cent of human carbon dioxide emissions, the biggest greenhouse gas blamed for climate change.
Charities such as Cool Earth, the organisation set up by Eliasch and former Labour minister Frank Field, could buy a tiny fraction of the rainforest, but their popularity 'diverts attention' from the more urgent need to return rainforest to indigenous people, claims Stephen Corry, Survival International's director.
'It's like a bucket of water in the North Sea: the amount of land that's being bought by outsiders is infinitesimally small, and if you look at [the land bought by Cool Earth] there's 15,000 times more land protected because it's under indigenous control in the Amazon,' said Corry. 'We're not saying it's imperialistic, we're not even saying there's anything wrong with it: what's wrong is the claims being put forward in its name, that this is a permanent solution.'
Matthew Owen, Cool Earth's director, defended the charity against claims that the benefits of buying rainforest were exaggerated. Cool Earth only bought land which had rights for logging and was on the 'frontier' of the risk of destruction, said Owen. The charity, which charges donors £70 an acre, has bought 32,000 acres in Brazil and Ecuador. An estimated 50 million acres of rainforest - an area the size of Britain - is cut down annually.
Cool Earth and other charities have previously been accused of 'green colonialism' - a criticism they tried to counter by giving the freehold of land to local organisations, along with funds and training to protect it, and encouraging local people to carry on traditional trades such as rubber tapping and gathering fruits and nuts. 'We give it to them with no strings attached except it's kept standing,' added Owen.
The Survival International report, 'Progress can Kill', says land ownership has the biggest impact on health of indigenous tribes because people separated from their land are prone to imported western diseases, suffer mental illnesses and high rates of suicide, said Corry.