HR: 0800h
AN: B41B-0454    [Abstracts]
TI: An assessment of the biophysical consequences of land use change and the implications for climate policy analysis
AU: * Snyder, C P
EM: cpsnyder@stanford.edu
AF: Interdisciplinary Program in Environment and Resources (IPER), Stanford University, Stanford, CA 94305, United States
AU: O'Neill, B C
EM: oneill@iiasa.ac.at
AF: International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, Laxenburg, A- 2361, Austria
AU: Obersteiner, M
EM: michael.obersteiner@gmail.com
AF: International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, Laxenburg, A- 2361, Austria
AB: Land use change (LUC) can impact global climate through several processes in addition to changing greenhouse gas (GHG) concentrations. Some contend that the biophysical effects of LUC can be as important as the direct effect on GHG emissions, and argue that the biophysical effects of LUC must be included in climate policy decisions. However, much uncertainty remains regarding the conditions under which these biophysical effects have significant impact on the global climate. We calculated a first order assessment of the magnitude and relative uncertainty for each of the processes by which LUC impacts global climate. Results from available, published model experiments on the climatic impacts of LUC were converted to a single common metric of radiative forcing, focusing on the biophysical effects of LUC and how such effects vary with latitude. We found that, under some conditions, the biophysical effects of LUC can alter the global climate more than GHG fluxes. The climatic effects of LUC vary significantly in magnitude by latitude, with biophysical processes having little net effect in the tropics but large effects in the high latitudes. Are these biophysical processes important to consider in climate analysis over the next century? We investigated the importance of these processes over projected baseline land use and under climate policy scenarios that include large amounts of biological carbon sequestration and/or bioenergy production. The importance of biophysical processes is highly dependent on the magnitude and spatial distribution of future land use. We found that current scenarios with large amounts of bioenergy from timber and/or afforestation in temperate and boreal latitudes likely will result in significantly higher warming than the temperature target. This research illustrates the importance of including the biophysical impacts of LUC and spatially explicit land use projections for robust climate policy analyses. Climate projections that include only aggregate GHG fluxes from LUC are vulnerable to significant miscalculations, on the order of up to 1K in global mean surface temperature.
DE: 0485 Science policy (6620)
DE: 1622 Earth system modeling (1225)
DE: 1626 Global climate models (3337, 4928)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1632 Land cover change
SC: Biogeosciences [B]
MN: 2007 Fall Meeting