HR: 10:35h
AN: B22B-02    [Abstracts]
TI: On the Hydrological Impact of Future Climate-Induced Vegetation Changes
AU: Alo, C A
EM: clement.alo@huskymail.uconn.edu
AF: University of Connecticut, Department of Civil & Environmental Engineering, Storrs, CT 06269, United States
AU: * Wang, G
EM: gwang@engr.uconn.edu
AF: University of Connecticut, Department of Civil & Environmental Engineering, Storrs, CT 06269, United States
AB: This study uses the NCAR CLM3 and CLM3-DGVM to investigate how predicted vegetation changes influences the surface hydrologic responses to elevated CO2 and attendant climate changes projected by 8 GCMs under the SRESA1B scenario. Pre-industrial control (PICNTRL) and SRESA1B scenarios of equilibrium vegetation structure (leaf area index (LAI) and vegetation coverage) are simulated by the dynamic global vegetation model CLM3-DGVM. For climate change forcing from each GCM, comparisons are made among three surface hydrology simulations using CLM3.0 driven with different combinations of climate forcing and potential natural vegetation in order to separate the effect of structural vegetation feedback from the combined influence of climate and CO2 changes. With the exception of the HadCM scenario, all other GCM scenarios broadly agree on spatial patterns of structural vegetation feedbacks on surface temperature and the surface water budget, although the response of soil moisture varies considerably among the GCM scenarios especially in the tropics. With the HadCM excluded, averages over the seven GCM scenarios indicate that the CO2-induced warming in winter is stronger than in summer in the northern mid- and high-latitudes, and structural vegetation feedback enhances the winter warming (due to masking of snow by increased LAI) and reduces the summer warming (due to increased evapotranspiration with increased LAI) over a large portion of these regions; the global hydrological cycle is expected to accelerate in a warmer climate, and structural vegetation feedback increases evapotranspiration under future climate, thereby further accelerating the hydrological cycle. Measured by evapotranspiration flux, this hydrological acceleration by structural vegetation feedback is at a magnitude comparable to that due to CO2 and climate changes. The impact of vegetation changes corresponding to the HadCM-projected climate changes is markedly different, being either more extreme or in a different direction than those corresponding to the other GCMs examined.
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0466 Modeling
DE: 1632 Land cover change
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting