Biofuels meant to help alleviate greenhouse gas emissions may be in fact
contributing to climate change when grown on converted tropical forest lands,
warns a comprehensive study published earlier this month in the journal
Environmental Research Letters.
The new research looks at the "carbon payback time" or "carbon debt" of various
biofuel feedstocks including oil palm, sugar cane, and soy. Carbon payback time
refers to the number of years it takes for the emissions saved by the
replacement of fossil fuels with biofuel to offset the carbon emissions
generated when the land is converted for growing the biofuel feedstock.
Analyzing the carbon debt for biofuel crops grown in ecosystems around the
world, Holly Gibbs and colleagues report that "while expansion of biofuels into
productive tropical ecosystems will always lead to net carbon emissions for
decades to centuries... [expansion] into degraded or ...