HR: 1330h
AN: A42B-0758    [PDF]
TI: Carbon Cycle Sensitivity to Climate Change: Results from a Comprehensive GCM-Based Climate and Carbon Cycle Model
AU: * Govindasamy, B
EM: bala@llnl.gov
AF: Lawrence Livermore Nat'l Lab, 7000 East Ave. L-103, Livermore, CA 94550 United States
AU: Thompson, S L
EM: thompson59@llnl.gov
AF: Lawrence Livermore Nat'l Lab, 7000 East Ave. L-103, Livermore, CA 94550 United States
AU: Mirin, A
EM: mirin1@llnl.gov
AF: Lawrence Livermore Nat'l Lab, 7000 East Ave. L-103, Livermore, CA 94550 United States
AU: Wickett, M
EM: wickett@llnl.gov
AF: Lawrence Livermore Nat'l Lab, 7000 East Ave. L-103, Livermore, CA 94550 United States
AU: Delire, C
EM: cldelire@facstaff.wisc.edu
AF: University of Wisconsin, 1225 W. Dayton St., Madison, WI 53706 United States
AB: We use an interactive global climate and carbon cycle model to perform simulations of climate change from 1870 AD to 2100 AD forced by anthropogenic emissions of greenhouse gases. The goal of this effort is to include and better understand feedbacks between the climate system and the carbon cycle. We use the Parallel Climate Model 2 (PCM-2) developed at NCAR as our climate model. The PCM-2 includes a version of NCAR's CCM3 for the atmospheric GCM and a version of the POP model for the ocean GCM. The horizontal resolutions for atmosphere and ocean are T42 truncation (about 280 km) and 0.7 degrees (about 75 km), respectively. The ocean carbon model is based on OCMIP protocols, but modified to eliminate the phosphate-restoring restriction. The terrestrial biosphere model is IBIS-2 which simulates biophysical and biogeochemical surface fluxes and includes a dynamic vegetation model. The model is integrated to a pre-industrial equilibrium using a prescribed atmospheric CO2 concentration of 290 ppmv. This equilibrated state serves as the starting point for three transient simulations. The Control Case assumes historical greenhouse emissions up to year 2000, then uses SRES A2 emissions up to year 2100. A Double Sensitivity Case is the same as the Control case, except that the greenhouse radiative forcing of climate is doubled so that the climate response is doubled. In Zero Sensitivity Case, the greenhouse radiative forcing is held fixed at preindustrial value so that there is no climate response to greenhouse forcing. The range of global- and annual-mean surface warming in these 3 experiments encompasses the range projected by IPCC for a doubling of atmospheric CO2. We will discuss the sensitivity of modelˆs carbon cycle for this range of global climate change. We will specifically discuss the sensitivity of terrestrial carbon uptake to changes in the magnitude of global warming.
DE: 0315 Biosphere/atmosphere interactions
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical processes (4805)
DE: 3322 Land/atmosphere interactions
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting