American Geophysical Union 2008 Fall Meeting
“… motivations for advancing corn-based ethanol production
in the USA, such as reduced reliance on foreign oil and increased
prosperity for farming communities, must be considered separately,
but the greenhouse-gas-mitigation rationale is clearly unsupportable.”
Greenhouse-Gas Consequences of US Corn-based Ethanol in a Flat
Davidson, E A., et al firstname.lastname@example.org
The Woods Hole Research Center, 149 Woods Hole Road, Falmouth,
MA 02540- 1644, United States.
Abstract: Competition for arable land is now occurring among food, fiber, and fuel production sectors. In the USA, increased corn production for ethanol has come primarily at the expense of reduced soybean production. Only a few countries, mainly Brazil, have appropriate soils, climate, and infrastructure needed for large absolute increases in cropped area in the next decade that could make up the lost US soybean production. Our objective is to improve estimates of the potential net greenhouse gas (GHG) consequences, both domestically and in Brazil, of meeting the new goals established by the US Congress for expansion of corn-based ethanol in the USA. To meet this goal of 57 billion liters per year of corn-based ethanol production, an additional 1-7 million hectares will need to be planted in corn, depending upon assumptions regarding future increases in corn yield. Net GHG emissions saved in the USA by substituting ethanol for gasoline are estimated at 14 Tg CO2-equivalents once the production goal of 57 million L/yr is reached. If reduced US soybean production caused by this increase in US corn planting results in a compensatory increase in Brazilian production of soybeans in the Cerrado and Amazon regions, we estimate a potential net release of 1800 to 9100 Tg CO2-equivalents of GHG emissions due to land-use change. Many opportunities exist for agricultural intensification that would minimize new land clearing and its environmental impacts, but if Brazilian deforestation is held to only 15% of the area estimated here to compensate lost US soybean production, the GHG mitigation of US corn-based ethanol production during the next 15 years would be more than offset by emissions from Brazilian land-use change. Other motivations for advancing corn-based ethanol production in the USA, such as reduced reliance on foreign oil and increased prosperity for farming communities, must be considered separately, but the greenhouse-gas-mitigation rationale is clearly unsupportable.
“…biophysical effects depend largely on albedo and evapotranspiration
Climate effects of biofuels: measuring some key parameters. Lobell,
D, et al email@example.com
Abstract: Many of the recent changes in the global food system have been associated, directly or indirectly, with a rapid expansion of biofuel production. One of the main scientific challenges associated with these changes is to understand the effects on the climate system, and in particular whether there are hotspots where biofuel production is especially good or bad for climate protection. The climate effects of biofuels depend on both net changes in greenhouse gas balance and direct biophysical effects of land cover changes. Recent work has shown that the first of these depends critically on assumptions about indirect land use changes that result from biofuel-induced price increases, and in particular on assumptions about how productive biomass agriculture in marginal areas will be. The biophysical effects depend largely on albedo and evapotranspiration changes that can be location and crop specific. Here we will present recent research results on each of these topics, with a focus on marginal land productivity in the United States and land use changes in Brazil.