The carbon dioxide emissions caused by the  destruction of tropical forests have been  significantly overestimated, according to a new study. The work could undermine  attempts to pay poor countries to protect forests as a cost-effective way to  tackle global warming.
The loss of forests in countries such as Brazil and  Indonesia is widely assumed to account for about 20% of all carbon dioxide  produced by human activity – more than the world's transport system. The 20%  figure was published by the Intergovernmental Panel on Climate Change  in 2007 and was widely quoted after being highlighted by the Stern review on the  economics of the problem. It is repeatedly used by Prince Charles and others as  an incentive to push efforts to include forests in carbon trading.
Curbing emissions from deforestation is one of the main issues being  discussed at a UN climate meeting in Barcelona this week, before crucial talks  in Copenhagen next month.