Details

Autor(en) / Beteiligte

• Cao, Long
• Bala, Govindasamy
• Caldeira, Ken
• Nemani, Ramakrishna
• Ban-Weiss, George

Titel

Importance of carbon dioxide physiological forcing to future climate change

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2010-05, Vol.107 (21), p.9513-9518

Ort / Verlag

United States: National Academy of Sciences

Erscheinungsjahr

2010

Quelle

MEDLINE

Beschreibungen/Notizen

• An increase in atmospheric carbon dioxide (CO₂) concentration influences climate both directly through its radiative effect (i.e., trapping longwave radiation) and indirectly through its physiological effect (i.e., reducing transpiration of land plants). Here we compare the climate response to radiative and physiological effects of increased CO₂ using the National Center for Atmospheric Research (NCAR) coupled Community Land and Community Atmosphere Model. In response to a doubling of CO₂, the radiative effect of CO₂ causes mean surface air temperature over land to increase by 2.86 ± 0.02 K (± 1 standard error), whereas the physiological effects of CO₂ on land plants alone causes air temperature over land to increase by 0.42 ± 0.02 K. Combined, these two effects cause a land surface warming of 3.33 ± 0.03 K. The radiative effect of doubling CO₂ increases global runoff by 5.2 ± 0.6%, primarily by increasing precipitation over the continents. The physiological effect increases runoff by 8.4 ± 0.6%, primarily by diminishing evapotranspiration from the continents. Combined, these two effects cause a 14.9 ± 0.7% increase in runoff. Relative humidity remains roughly constant in response to CO₂-radiative forcing, whereas relative humidity over land decreases in response to CO₂-physiological forcing as a result of reduced plant transpiration. Our study points to an emerging consensus that the physiological effects of increasing atmospheric CO₂ on land plants will increase global warming beyond that caused by the radiative effects of CO₂.