The Department of the Interior recently released the first in a series of regional studies measuring the amount of carbon stored in U.S. ecosystems. Published by Interior’s U.S. Geological Survey (USGS), the study examines the current and projected future carbon storage in the Great Plains region as part of a nationwide assessment.
This is the first regional report applying a comprehensive methodology designed by the USGS in 2010 to assess how much carbon is stored in various ecosystems, such as wetlands, forests and rangelands. The study covers an area of the United States that includes parts of 14 states ranging from eastern Montana to southern Texas and eastern Iowa.
A key finding in the Great Plains study is that the region is currently an overall “carbon sink,” meaning it takes up more carbon than it emits. In addition, the amount of carbon sequestered offsets most of the emissions of nitrous oxide and methane from this region.
On a national scale, the amount of carbon that is currently stored per year in ecosystems within the Great Plains is about 21% of emissions from personal vehicles and 3.6% of total fossil fuel emissions nationwide. The values for vehicle and total fossil fuel emissions, not part of the USGS study, were calculated using the 2009 EPA national greenhouse gas inventory report.
Using the uniform methodology developed by USGS also allows for comparisons between regions and ecosystems. For example, the regional study shows that the southern part of the Great Plains has a substantial amount of woody vegetation, which has a strong potential to store additional carbon. Agricultural lands in the eastern part of the Great Plains similarly have a strong potential to store carbon; however, these areas also are associated with high greenhouse gas emissions.
Following the Great Plains study, the USGS is expected to release studies on the western, eastern, Alaskan and Hawaiian regions. The full national assessment is expected to be completed in 2013.
"For the first time, we will have a comprehensive view of how carbon is cycling through our nation's ecosystems: sources, sinks, and relative residence times in the various biological components," explained USGS Director Marcia McNutt. "This study will not only result in better land-use decisions, but should also advance our fundamental understanding of one of the most important chemical cycles on the planet."
As part of the study, USGS scientists produced current carbon storage estimates and made projections into the year 2050. Future estimates incorporate Intergovernmental Panel on Climate Change projections of climate change as well as USGS projections of land use and land cover change. By 2050, the USGS study estimates that carbon stored in the region is expected to increase by 29 to 36%, while emissions of nitrous oxide are expected to increase by 7 to 11%, and methane is expected to change by -1.6 to 16%.
“This report will give tools to the policymakers, land managers and the public to make sound decisions, such as whether to restore wetlands, harvest trees, develop agricultural lands or consider no-till farming practices,” said Deputy Secretary of the Interior David J. Hayes. For example, a community might need to decide whether to convert grasslands and forests to croplands or urban areas to meet the demands of a growing population. Such decisions have varying consequences related to carbon sequestration and greenhouse gas emissions.
Changes in carbon storage are driven by both short - and long-term changes to the landscape. In the Great Plains, carbon storage is expected to increase based on near-future land use and management practices, such as decreased timber harvesting and changes to crop management, including expanded fertilizer applications and no-till farming. The rate of increase is projected to slow somewhat over time due to climate change and land-use transitions, such as grasslands or forests conversion to croplands or urban areas.
Research conducted by USGS scientists on the carbon cycle and potential for carbon sequestration was mandated by the Energy Independence and Security Act of 2007. In addition to the biological carbon sequestration assessment, the USGS is also assessing the nation’s potential for geologic carbon sequestration, which is the storage of carbon dioxide in underground rock formations.
The report, “Baseline and Projected Future Carbon Storage and Greenhouse-Gas Fluxes in the Great Plains Region of the United States,” can be found online in the USGS publications warehouse at http://pubs.usgs.gov/pp/1787/.