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Climate response to physiological forcing of carbon dioxide simulated by the coupled Community Atmosphere Model (CAM3.1) and Community Land Model (CLM3.0)
Author(s) -
Cao Long,
Bala Govindasamy,
Caldeira Ken,
Nemani Ramakrishna,
BanWeiss George
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl037724
Subject(s) - transpiration , evapotranspiration , environmental science , canopy conductance , canopy , forcing (mathematics) , atmosphere (unit) , atmospheric sciences , water cycle , radiative forcing , stomatal conductance , carbon dioxide , climate model , climatology , carbon cycle , climate change , atmospheric model , meteorology , ecology , vapour pressure deficit , photosynthesis , botany , ecosystem , geology , biology , geography
Increasing concentrations of atmospheric CO 2 decrease stomatal conductance of plants and thus suppress canopy transpiration. The climate response to this CO 2 ‐physiological forcing is investigated using the Community Atmosphere Model version 3.1 coupled to Community Land Model version 3.0. In response to the physiological effect of doubling CO 2 , simulations show a decrease in canopy transpiration of 8%, a mean warming of 0.1K over the land surface, and negligible changes in the hydrological cycle. These climate responses are much smaller than what were found in previous modeling studies. This is largely a result of unrealistic partitioning of evapotranspiration in our model control simulation with a greatly underestimated contribution from canopy transpiration and overestimated contributions from canopy and soil evaporation. This study highlights the importance of a realistic simulation of the hydrological cycle, especially the individual components of evapotranspiration, in reducing the uncertainty in our estimation of climatic response to CO 2 ‐physiological forcing.