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Sensitivity of greenhouse summer dryness to changes in plant rooting characteristics
Author(s) -
Milly P. C. D.
Publication year - 1997
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 - 10.1029/96gl03968
Subject(s) - dryness , environmental science , carbon dioxide , evapotranspiration , atmospheric sciences , soil water , greenhouse , greenhouse gas , agronomy , hydrology (agriculture) , climatology , soil science , ecology , biology , geology , immunology , geotechnical engineering
A possible consequence of increased concentrations of greenhouse gases in Earth's atmosphere is “summer dryness,” a decrease of summer plant‐available soil water in middle latitudes, caused by increased availability of energy to drive evapotranspiration. Results from a numerical climate model indicate that summer dryness and related changes of land‐surface water balances are highly sensitive to possible concomitant changes of plant‐available water‐holding capacity of soil, which depends on plant rooting depth and density. The model suggests that a 14% decrease of the soil volume whose water is accessible to plant roots would generate the same summer dryness, by one measure, as an equilibrium doubling of atmospheric carbon dioxide. Conversely, a 14% increase of that soil volume would be sufficient to offset the summer dryness associated with carbon‐dioxide doubling. Global and regional changes in rooting depth and density may result from (1) plant and plant‐community responses to greenhouse warming, to carbon‐dioxide fertilization, and to associated changes in the water balance and (2) anthropogenic deforestation and desertification. Given their apparently critical role, heretofore ignored, in global hydroclimatic change, such changes of rooting characteristics should be carefully evaluated using ecosystem observations, theory, and models.