Trees are responsible for absorbing a fifth of man's climate change emissions, scientists have discovered, in the most compelling evidence yet on the need to stop deforestation.
Previous studies on the value of the rainforests had concentrated on South America and Asia.
But new research has included tropical forests in Africa to give the most up-to-date picture of the amount of carbon dioxide absorbed by trees. It found 4.8 billion tonnes of CO2 are sucked up every year.
The study suggest trees are currently sucking up a significant amount of global pollution from factories and cars but if carbon emissions continue to increase forests will die or even burn out, causing a "feed back" effect that will accelerate climate change.
The research is being hailed as a breakthrough for climate change science and will be used to put further pressure on world leaders to halt deforestation.
The 40-year study of African tropical forests, one third of the world's total tropical forest, showed that for at least the last few decades each hectare of intact African forest has trapped an extra 0.6 tonnes of carbon per year.
Scientists then added the new data to existing information on South American and Asian forests. The final analysis of 250,000 tree records was published in Nature.
Dr Simon Lewis, a Royal Society research fellow at the University of Leeds and author of the paper, said: "We are receiving a free subsidy from nature.
"Tropical forest trees are absorbing about 18 per cent of the CO2 added to the atmosphere each year from burning fossil fuels, substantially buffering the rate of climate change."