Credit: P. FRIDMAN/CORBIS

The rapid expansion of sugar cane cultivation (pictured) for biofuels in Brazil may be cooling the local climate.

Scott Loarie at the Carnegie Institution for Science in Stanford, California, and his team analysed remote-sensing data for factors including land cover, temperature and albedo (reflectivity) in the Brazilian savannah, where sugar cane acreage is on the rise. They found that temperatures in the region increase by an average of 1.55 °C when natural vegetation is converted to non-cane crops or pasture, largely because of decreased water evaporation and transpiration (evaporation from plants). However, when planted on land already used for agriculture, sugar cane crops cool temperatures by 0.93 °C, thanks to greater evaporation and transpiration, and higher albedo.

The authors cite this as evidence that sugar cane's climate benefits will be greatest if restricted to existing agricultural lands and if the plant's cultivation does not drive deforestation elsewhere.

Nature Clim. Change doi:10.1038/nclimate1067 (2011)