Natural Resources, School of



Jingfeng Xiao, Purdue UniversityFollow
Qianlai Zhuang, Purdue University
Beverly E. Law, Oregon State UniversityFollow
Dennis D. Baldocchi, University of California - BerkeleyFollow
Jiquan Chen, University of ToledoFollow
Andrew D. Richardson, Harvard UniversityFollow
Jerry M. Melillo, Marine Biological Laboratory
Kenneth J. Davis, Pennsylvania State UniversityFollow
David Y. Hollinger, USDA Forest Service
Sonia Wharton, University of California
Ram Oren, Duke University
Asko Noormets, North Carolina State University
Marc L. Fischer, Lawrence Berkeley National LaboratoryFollow
Shashi Verma, University of Nebraska - LincolnFollow
David R. Cook, Argonne National Laboratory
Ge Sun, USDA Forest Service
Steve McNulty, USDA Forest Service
Steven C. Wofsy, Harvard University
Paul V. Bolstad, University of Minnesota
Sean P. Burns, University of Colorado at Boulder
Peter S. Curtis, Ohio State UniversityFollow
Bert G. Drake, Smithsonian Environmental Research Center
Matthias Falk, University of California - Davis
David R. Foster, Harvard University
Lianhong Gu, Oak Ridge National Laboratory Environmental Sciences Division
Julian L. Hadley, Harvard University
Gabriel G. Katul, Duke University
Marcy Litvak, University of New MexicoFollow
Siyan Ma, University of California - Berkeley
Timothy A. Martin, University of FloridaFollow
Roser Matamala, Argonne National Laboratory
Tilden P. Meyers, NOAA/ARL
Russell K. Monson, University of Colorado at Boulder
J. William Munger, Harvard University
Walter C. Oechel, San Diego State University
U. Kyaw Tha Paw, University of California
Hans Peter Schmid, Indiana University
Russell L. Scott, USDA-ARS Southwest Watershed Research Center
Gregory Starr, University of Alabama
Andrew E. Suyker, University of Nebraska - LincolnFollow
Margaret S. Torn, Lawrence Berkeley National Laboratory

Document Type


Date of this Version



Agricultural and Forest Meteorology 151 (2011) 60–69; doi:10.1016/j.agrformet.2010.09.002


More accurate projections of future carbon dioxide concentrations in the atmosphere and associated climate change depend on improved scientific understanding of the terrestrial carbon cycle. Despite the consensus that U.S. terrestrial ecosystems provide a carbon sink, the size, distribution, and interannual variability of this sink remain uncertain. Here we report a terrestrial carbon sink in the conterminous U.S. at 0.63 pg C yr−1 with the majority of the sink in regions dominated by evergreen and deciduous forests and savannas. This estimate is based on our continuous estimates of net ecosystem carbon exchange (NEE) with high spatial (1 km) and temporal (8-day) resolutions derived from NEE measurements from eddy covariance flux towers and wall-to-wall satellite observations from Moderate Resolution Imaging Spectroradiometer (MODIS). We find that the U.S. terrestrial ecosystems could offset a maximum of 40% of the fossil-fuel carbon emissions. Our results show that the U.S. terrestrial carbon sink varied between 0.51 and 0.70 pg C yr−1 over the period 2001–2006. The dominant sources of interannual variation of the carbon sink included extreme climate events and disturbances. Droughts in 2002 and 2006 reduced the U.S. carbon sink by ∼20% relative to a normal year. Disturbances including wildfires and hurricanes reduced carbon uptake or resulted in carbon release at regional scales. Our results provide an alternative, independent, and novel constraint to the U.S. terrestrial carbon sink.