Sensitivity of global climate model simulations to increased stomatal resistance and CO{sub 2} increases
- Macquarie Univ., New South Wales (Australia)
- Univ. of Technology, New South Wales (Australia)
Increasing levels of atmospheric CO{sub 2} will not only modify climate, they will also likely increase the water-use efficiency of plants by decreasing stomatal openings. The effect of the imposition of {open_quotes}doubled stomatal resistance{close_quotes} on climate is investigated in off-line simulations with the Biosphere-Atmosphere Transfer Scheme (BATS) and in two sets of global climate model simulations: for present-day and doubled atmospheric CO{sub 2} concentrations. The anticipated evapotranspiration decrease is seen most clearly in the boreal forests in the summer although, for the present-day climate (but not at 2 x CO{sub 2}), there are also noticeable responses in the tropical forests in South America. In the latitude zone 44{degrees}N to 58{degrees}N, evapotranspiration decreases by -15 W m{sup 2}, temperatures increase by =2 K, and the sensible heat flux by +15 W m{sup {minus}2}. Soil moisture is often, but less extensively, increased, which can cause increases in runoff. The responses at 2 x CO{sub 2} are larger in the 44{degrees}N to 58{degrees}N zone than elsewhere. Globally, the impact of imposing a doubled stomatal resistance in the present-day climate is an increase in the annually averaged surface air temperature of 0.13 K and a reduction in total precipitation of -0.82%. If both the atmospheric CO{sub 2} content and the stomatal resistance are doubled, the global response in surface air temperature and precipitation are +2.72 K and +5.01% compared with +2.67 K and + 7.73% if CO{sub 2} is doubled but stomatal resistance remains unchanged as in the usual {open_quotes}greenhouse{close_quotes} experiment. Doubling stomatal resistance as well as atmospheric CO{sub 2} results in increased soil moisture in northern midlatitudes in summer. 40 refs.. 17 figs., 5 tabs.
- OSTI ID:
- 121745
- Journal Information:
- Journal of Climate, Vol. 8, Issue 7; Other Information: PBD: Jul 1995
- Country of Publication:
- United States
- Language:
- English
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