Dr Pep Canadell, from the Global Carbon Project and CSIRO Marine and Atmospheric Research, says today in the journal Science that tropical deforestation releases 1.5 billion tonnes of carbon each year into the atmosphere.

"Deforestation in the tropics accounts for nearly 20 per cent of carbon emissions due to human activities," Dr Canadell says. "This will release an estimated 87 to 130 billion tonnes of carbon by 2100, which is greater than the amount of carbon that would be released by 13 years of global fossil fuel combustion. So maintaining forests as carbon sinks will make a significant contribution to stabilising atmospheric greenhouse gas concentrations."

In the first study of its kind, Dr Canadell joined an international team of experts from the US, UK, Brazil and France to compare data from 11 climate-carbon computer models. The results show that tropical forests continue to accumulate carbon through to the end of the century, although they may become less efficient at higher temperatures.

"The new body of information shows considerable value in preserving tropical forests such as those in the Amazon and Indonesia as carbon sinks, that they do not release the carbon back into the atmosphere as has been suggested," Dr Canadell says. "However, it also demonstrates the need to avoid higher levels of global warming, which could slow the ability of forests to accumulate carbon."

He says that while tropical deforestation will continue, slowing the amount of clearing will make significant impacts. "If by 2050 we slow deforestation by 50 per cent from current levels, with the aim of stopping deforestation when we have 50 per cent of the world’s tropical forests remaining, this would save the emission of 50 billion tonnes of carbon into the atmosphere. This 50/50/50 option would avoid the release of the equivalent of six years of global fossil fuel emissions."

Reducing deforestation is just one of a portfolio of mitigation options needed to reduce concentrations of greenhouse gases in the atmosphere.

"Globally, we need a range of actions to reduce the build up of carbon in the atmosphere," Dr Canadell says. "This study ensures we have a sound scientific basis behind the consideration of deforestation reduction."

Source: CSIRO Australia.