Biofuels 'can add to warming'
2008-02-08 10:29
Washington - Clearing raw land to produce biofuels actually contributes to global warming by emitting large amounts of greenhouse gases into the atmosphere, researchers warned on Thursday.
Carbon dioxide (CO2) emissions from new croplands carved into rainforests, savannas, wetlands or grasslands would easily surpass the overall amount of CO2 emissions reduced through the use of biofuels, according to a report in the February 8 edition of Science.
"If you're trying to mitigate global warming, it simply does not make sense to convert land for biofuels production," said Joe Fargione, a founder of private environment protection agency the Nature Conservancy and co-author of the study.
"All the biofuels we use now cause habitat destruction, either directly or indirectly," he said.
"Global agriculture is already producing food for six billion people. Producing food-based biofuel, too, will require that still more land be converted to agriculture."
Converting land to grow corn, sugar cane or soy beans - crops used in the production of biofuels - creates a "biofuel carbon debt" by releasing 17 to 420 times as much CO2 into the atmosphere as the greenhouse gas reductions which the biofuels provide by displacing fossil fuels.
Carbon is stored in dead trees and plants as well as in the soil, and naturally seeps into the atmosphere in the form of CO2. Converting native habitats to cropland increases the release of CO2 into the air, the report said.
Increases in carbon emissions
It would take years, and in some cases centuries, before biofuels derived from crops on converted land would lead to a net reduction of greenhouse gases, according to the report.
The researchers calculated that in Indonesia, where wetlands are being converted to grow palm oil to produce biofuels, it will take 423 years before biofuel CO2 emmission savings would repay the carbon debt caused by the land conversion.
"We don't have proper incentives in place because landowners are rewarded for producing palm oil and other products but not rewarded for carbon management," said report co-author Stephen Polasky, an applied economics professor at University of Minnesota.
"This creates incentives for excessive land clearing and can result in large increases in carbon emissions."
An incentive for carbon sequestration or a penalty for carbon emmissions is needed in order to slow CO2 emissions and environmental destruction, Polasky said.
The researchers noted that strong growth in the demand for corn-based ethanol in the United States has led to the increasing destruction of the Amazon rainforest in Brazil.
To address the ethanol demand, US farmers have stopped rotating corn crops with soy, leaving their Brazilian counterparts to produce more soybeans to meet rising global demand, resulting in further Amazon deforestation, they said.
The report stresses that certain biofuels do not contribute to global warming because they leave the natural ecosystem intact, and that obtaining biofuels from biomass waste or forestry products such as wood chips causes less harm to the environment and is the aim of several scientists.