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Sensitivity of Terrestrial Water and Energy Budgets to CO2-Physiological Forcing: An Investigation Using an Offline Land ModelIncreasing concentrations of atmospheric carbon dioxide (CO2) influence climate by suppressing canopy transpiration in addition to its well-known greenhouse gas effect. The decrease in plant transpiration is due to changes in plant physiology (reduced opening of plant stomata). Here, we quantify such changes in water flux for various levels of CO2 concentrations using the National Center for Atmospheric Research s (NCAR) Community Land Model. We find that photosynthesis saturates after 800 ppmv (parts per million, by volume) in this model. However, unlike photosynthesis, canopy transpiration continues to decline at about 5.1% per 100 ppmv increase in CO2 levels. We also find that the associated reduction in latent heat flux is primarily compensated by increased sensible heat flux. The continued decline in canopy transpiration and subsequent increase in sensible heat flux at elevated CO2 levels implies that incremental warming associated with the physiological effect of CO2 will not abate at higher CO2 concentrations, indicating important consequences for the global water and carbon cycles from anthropogenic CO2 emissions. Keywords: CO2-physiological effect, CO2-fertilization, canopy transpiration, water cycle, runoff, climate change 1.
Document ID
20120003648
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Gopalakrishnan, Ranjith
(Indian Inst. of Science Bangalore, India)
Bala, Govindsamy
(Indian Inst. of Science Bangalore, India)
Jayaraman, Mathangi
(Indian Inst. of Science Bangalore, India)
Cao, Long
(Carnegie Institution of Washington Stanford, CA, United States)
Nemani, Ramakrishna
(NASA Ames Research Center Moffett Field, CA, United States)
Ravindranath, N. H.
(Indian Inst. of Science Bangalore, India)
Date Acquired
August 25, 2013
Publication Date
November 14, 2011
Publication Information
Publication: Environmental Research Letters
Volume: 6
Issue: 4
ISSN: 1748-9326
Subject Category
Geophysics
Funding Number(s)
CONTRACT_GRANT: NNX08AF83A
CONTRACT_GRANT: DST0948
Distribution Limits
Public
Copyright
Other

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