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.
Of course, the expanding populations are a bad idea too.
Tearing down rain forests to plant biofuel crops causes huge carbon dioxide emissions that far exceed any reduced CO2 emissions caused by using biomass energy in place of oil.
"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.
The scientists found that addressing the land-based carbon is essential for stabilizing greenhouse gases at low levels. Overall, land contains 2,000 billion tons of carbon, compared to the 750 billion tons in the atmosphere. In addition, forests hold more carbon than grazing does. Converting land from forest to food or bioenergy crops releases carbon into the atmosphere. Conversely, turning agricultural land back into forests tucks carbon away on land, reducing it in the atmosphere.
Now, I think that tearing down all the forests to enable the human population to continue to grow is a bad idea for other reasons. I don't see any benefit for existing people from the addition of another billion people and I see a lot of costs.
Some University of Minnesota researchers argue that the health and environmental costs of cellulosic ethanol are much lower than the costs of gasoline and corn ethanol.
Total environmental and health costs of gasoline are about 71 cents per gallon, while an equivalent amount of corn-ethanol fuel costs from 72 cents to about $1.45, depending on the technology used to produce it. An equivalent amount of cellulosic ethanol, however, costs from 19 cents to 32 cents, depending on the technology and type of cellulosic materials used.
But if existing rain forests are harvested for the cellulose then the net effect would be increase the amount of carbon dioxide in the atmosphere. Cellulosic technology can play a useful role in processing lawn clippings and other biomass wastes. But a big scaling up to produce cellulose from crops is a bad idea.
|Share |||Randall Parker, 2009 February 17 11:04 PM Energy Biomass|