Farmers across the tropics might raze forests to plant biofuel crops, according to new research by Holly Gibbs, a postdoctoral researcher at Stanford's Woods Institute for the Environment.
"If we run our cars on biofuels produced in the tropics, chances will be good that we are effectively burning rainforests in our gas tanks," she warned.
Policies favoring biofuel crop production may inadvertently contribute to, not slow, the process of climate change, Gibbs said. Such an environmental disaster could be "just around the corner without more thoughtful energy policies that consider potential ripple effects on tropical forests," she added.
Gibbs' predictions are based on her new study, in which she analyzed detailed satellite images collected between 1980 and 2000. The study is the first to do such a detailed characterization of the pathways of agricultural expansion throughout the entire tropical region. Gibbs hopes that this new knowledge will contribute to making prudent decisions about future biofuel policies and subsidies.
"If biofuels are grown in place of forests, we're actually going to end up emitting a huge amount of carbon. When trees are cut down to make room for new farmland, they are usually burned, sending their stored carbon to the atmosphere as carbon dioxide. That creates what's called a carbon debt," Gibbs said. "This is because the carbon lost from deforestation is much greater than the carbon saved from using the current-generation biofuels."
Indeed, tropical forests are the world's most efficient storehouses for carbon, harboring more than 340 billion tons, according to Gibbs' research. This is equivalent to more than 40 years worth of global carbon dioxide emissions from burning fossil fuels.
Gibbs' previous findings asserted that the carbon debt incurred from cutting down a tropical forest could take several centuries or even millennia to repay through carbon savings produced from the resultant biofuels.