Weird Science: Sugar Cane Cools Climate

Jack Delano / Library of Congress

Sugar cane worker in the rich field, vicinity of Guanica, Puerto Rico (circa 1939).

Scientists from the Carnegie Institution's Department of Global Ecology studied satellite images stretching over 733,000 square miles of Brazil, where approximately 25% of their automobile fuel comes from sugar cane. They measured temperature, reflectivity and evapotranspiration (the water loss from the soil and from plants as they exhale water vapor). Their conclusion: Expansion of the sugar cane crop cools the local climate by reflecting sunlight back into space and lowering the temperature of the surrounding air as the plants "exhale" cooler water. The study is published in the latest issue of Nature Climate Change.

There is, however, a caveat.

These effects are contingent on sugar cane being grown in areas previously occupied by crops or pastureland, not in areas converted from natural vegetation. In fact, the study's authors emphasize how important is to maintain areas of natural vegetation. Transforming such areas into crops and pastureland would actually contribute to deforestation.