HR: 11:15h
AN: U51C-04    [PDF]
TI: How Has Urbanization Altered the Carbon Cycle in the United States?
AU: * Imhoff, M L
EM: marc.l.imhoff@nasa.gov
AF: Biospheric Sciences Branch, NASA's Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Bounoua, L
EM: bounoua@dounia.gsfc.nasa.gov
AF: Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20742 United States
AU: DeFries, R
EM: rdefries@geog.umd.edu
AF: Department of Geography, University of Maryland, College Park, MD 20742 United States
AU: Lawrence, W
EM: blawrenc@bowiestate.edu
AF: Department of Natural Sciences, Bowie State University, Bowie, MD 20715
AU: Ricketts, T
EM: taylor.ricketts@wwfus.org
AF: World Wildlife Fund, 1250 Twenty-fourth St. NW, Washington, DC 20037 United States
AB: Data from two satellites and a terrestrial carbon model were used to quantify the impact of urbanization on net primary productivity (NPP) and its consequences on carbon balance and food production. We found that different classes of urbanization have a recognizable satellite-based NDVI signal at a spatial resolution of 1 km. Our results show that urbanization is taking place on the most fertile lands and hence has a disproportionately large overall negative impact on regional and even continental scale NPP. Urban land transformation in the U.S. has reduced the amount of carbon fixed through photosynthesis by 1.6 percent of the pre-urban value. The reduction nearly offsets the 1.8 percent gain made by the conversion of land to agricultural use, a striking fact given that urbanization covers less than 3 percent of the land in the U.S. while agricultural lands approach 29 percent. At local and regional scales, urbanization increases NPP in resource-limited regions, and through localized warming "urban heat" contributes to the extension of the growing season in cold regions. In terms of biologically available energy, the loss of NPP due to urbanization of agricultural lands alone is equivalent to the caloric requirement of about 6 percent of the US population annually.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical processes (4805)
DE: 1620 Climate dynamics (3309)
SC: U
MN: 2003 Fall Meeting