HR: 1330h
AN: B42A-0946    [PDF]
TI: Quantifying the Uncertainties in the Carbon Content of the Terrestrial Biosphere
AU: * Jain, A K
EM: jain@atmos.uiuc.edu
AF: University of Illinois, department of atmospheric sciences, 105 S. Gregory St, Urbana, IL 61801 United States
AU: Yang, X
EM: xyang5@uiuc.edu
AF: University of Illinois, department of atmospheric sciences, 105 S. Gregory St, Urbana, IL 61801 United States
AB: According to the IPCC (2001), the 1980s estimates for all major terms in the global carbon budget are subject to uncertainties. However, uncertainties in land use changes and terrestrial sinks are the largest, up to 200%. Here, we quantify the uncertainties in regional land use emissions as well as net terrestrial flux over the period 1765-2000. Using the terrestrial carbon cycle component of the Integrated Science Assessment Model (ISAM) coupled with observed atmospheric CO2, temperature and precipitation data, the effects of different land cover data sets on the response of plant and soil carbon stocks are assessed. This geographically-explicit implementation of ISAM simulates the carbon fluxes to and from different compartments of the terrestrial biosphere with 0.5-by-0.5 degree spatial resolution. Each grid cell contains at least one of the thirteen land coverage classifications, which represent both highly managed land uses and less managed biomes. Changes in the areal extent of land cover classifications are driven by shifts in land use related to agriculture, afforestation, deforestation, and reforestation. Within each grid cell and land-coverage classification, the modeled carbon cycle includes feedback processes such as CO2 fertilization and temperature effects on photosynthesis, and respiration. ISAM model simulations indicate that uncertainties in net terrestrial fluxes during the 1980s is mainly due to the large uncertainties in land cover change data for tropical Africa and south and south east Asia.
DE: 0315 Biosphere/atmosphere interactions
DE: 0330 Geochemical cycles
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2003 Fall Meeting