Transforming ecosystems into farms for biofuel crops will increase global warming and result in net increases in carbon emissions, according to a study.
Scientists have found that converting rainforests, peatlands and grasslands can outweigh the carbon savings made from biofuels and produce "carbon debts" which could take centuries to pay off.
The study will add to concerns about the ability of biofuels to replace fossil fuels. The EU is reviewing its pledge that biofuels such as bioethanol and biodiesel should make up 10% of transport fuel by 2020. Britain has a separate target of 5% biofuels in petrol and diesel by 2010.
In the study, US researchers calculated that converting natural ecosystems to grow corn or sugarcane to produce ethanol, or palms or soybeans for biodiesel, could release between 17 and 420 times more carbon than the annual savings from replacing fossil fuels.
So can we please stop having governments trying to pick winners and making matters worse as they do so?