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Thursday, February 11, 2010

Estimates of Carbon Mitigation Potential from Agricultural and Forestry Activities

Renée Johnson
Specialist in Agricultural Policy

Jonathan L. Ramseur
Specialist in Environmental Policy

Ross W. Gorte
Specialist in Natural Resources Policy

In the United States, the agriculture and forestry sectors account for 6%-8% of current estimated total U.S. greenhouse gas (GHG) emissions annually. Combined, these sectors are estimated to emit more than 500 million metric tons CO2 equivalent (MMT CO2-Eq.) each year, most of which is emitted from the agriculture sector. 

Current estimates of the combined amount of carbon sequestered by the agriculture and forestry sectors is reported at more than 1,100 MMT CO2-Eq. per year, most of which is attributable to carbon stocks and uptake by trees in the forestry sector. 

Numerous studies estimate the additional GHG mitigation potential of farm and forestry activities. Among these, two commonly cited studies are those conducted by the U.S. Department of Agriculture (USDA) and the U.S. Environmental Protection Agency (EPA). 

Compared to current estimated mitigation potential levels, USDA and EPA projections provide a mostly positive picture of the potential for farm and forestry activities to mitigate GHG emissions. USDA and EPA project added mitigation potential of 590 to 990 MMT CO2-Eq. annually, thus increasing to roughly double current levels, assuming a high-end value or market price for carbon. At lower carbon prices, estimated additional mitigation potential is lower, but could still add about 40 to 160 MMT CO2-Eq. annually above current sequestration levels. 

These estimates are useful indicators of the potential for carbon storage in the agriculture and forestry sectors, which some in Congress see as potentially available for carbon offset allowances as part of a cap-and-trade program. A cap-and-trade system—as part of a GHG emissions reduction and trading program—is one possible approach being considered by Congress to address GHG emissions in the ongoing climate change debate. 

For policy decision-making, however, the results of studies such as those conducted by EPA and USDA to assess the carbon mitigation potential of farms and forests should be viewed with caution. These studies were published in 2004 and 2005, respectively, and use complicated simulation models largely based on data and market assumptions present in the late 1990s to early 2000s. Consequently, the available input data and modeling assumptions are limited in the extent to which they are able to accurately reflect both actual current conditions and longer-term future conditions. Given that these studies were developed prior to a variety of recent policy, market, and economic changes, some researchers now acknowledge that the published results of these studies are almost certainly outdated. Other related concerns include criticisms by prominent researchers of these modeling approaches and estimates. In addition, in the absence of defined policies outlining how an emission trading system would be designed and implemented, these models are limited in the extent to which they can depict future conditions under a regulatory system for sequestering carbon on farms and forests. 

In 2009 EPA updated its simulation models and underlying data and modeling assumptions. These changes to EPA's simulation models have implications for the agency's analysis of the overall estimated mitigation potential from agriculture and forestry activities, particularly for certain sequestration categories. Of particular concern to many in the U.S. agriculture sector, EPA's current estimates of the mitigation potential from agriculture soil carbon activities—such as conservation or no-till practices that preserve soil carbon—are sharply lower than previous EPA estimates.

Date of Report: January 26, 2010
Number of Pages: 25
Order Number: R40236
Price: $29.95

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