American Geophysical Union Annual Meetings, San Francisco, CA. December 13-17, 1999.
Simulations of potential vegetation distribution, natural fire frequency, carbon pools and fluxes are presented for two DGVMs (Dynamic Global Vegetation Model) involved in the second phase of Vegetation/Ecosystem Modeling and Analysis Project (VEMAP). Results represent a first attempt to link vegetation dynamics to biogeochemical cycling at a half-degree resolution for the conterminous USA. Two climate change scenarios were used: a cooler scenario from Hadley Climate Center (up to a 2.8 deg. C change in temperature in 2100) and a warmer scenario from the Canadian Climate Center (up to a 5.8 deg. C change in temperature in 2100). Both scenarios include sulfate aerosols and assume a CO2 increase (Is92a scenario) such that CO2 atmospheric concentration reaches 712ppm in year 2100. With the Hadley scenario, both DGVMs simulate increases in live vegetation carbon and total soil carbon. With the CCC scenario, both DGVMs simulate a decrease in live vegetation carbon. Both DGVMs predict an increase in total biomass burnt in the next century with a more pronounced increase for the CCC scenario. However, the models show some disagreement in their simulation of vegetation distribution under both scenarios with LPJ forecasting more extreme changes such as, in the Central Grasslands, desertification with the CCC scenario and the expansion of the deciduous forests with the Hadley scenario. We identify similarities in model behavior due to the climate forcing and explain some differences by the different structure of the models and their different sensitivity to CO2.
Figure 1: Simulation by 2 DGVMS (MC1 and LPJ) of the total biomass burnt (in Pg C) in the conterminous USA for 2 climate change scenarios: from the Hadley Climate Center (HAD) and one from the Canadian climate center (CCC).
Figure 2: Simulation by 2 DGVMS (MC1 and LPJ) of the total live vegetation (vegc) or soil (tslc) carbon biomass (in Pg C) in the conterminous USA for 2 climate change scenarios: from the Hadley Climate Center (HAD) and one from the Canadian climate center (CCC).
Figure 3: Simulation by 2 DGVMS (MC1 and LPJ) of net ecosystem productivity (nepx) (in g C m-2) in the conterminous USA for 2 climate change scenarios: from the Hadley Climate Center (HAD) and from the Canadian climate center (CCC).
Figure 4: Simulation by 2 DGVMS (MC1 and LPJ) of total live vegetation (vegc) (in Pg C) per vegetation type in the conterminous USA for the Hadley climate change scenario. (Coniferous, Deciduous, Mixed and Tropical forests, Savannas, Grasslands and Deserts)
Figure 5: Simulation by 2 DGVMS (MC1 and LPJ) of total live vegetation (vegc) (in Pg C) per vegetation type in the conterminous USA for the CCC climate change scenario. (Coniferous, Deciduous, Mixed and Tropical forests, Savannas, Grasslands and Deserts)
Figure 6: Simulation by 2 DGVMS (MC1 and LPJ) of vegetation distribution in the conterminous USA for the Hadley climate change scenario.
Figure 7: Simulation by 2 DGVMS (MC1 and LPJ)
of vegetation distribution in the conterminous USA for the CCC climate change scenario.
