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Soil Moisture and Other Hydrological Changes in a Stratospheric Aerosol Geoengineering Large Ensemble
Author(s) -
Cheng Wei,
MacMartin Douglas G.,
Dagon Katherine,
Kravitz Ben,
Tilmes Simone,
Richter Jadwiga H.,
Mills Michael J.,
Simpson Isla R.
Publication year - 2019
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2018jd030237
Subject(s) - environmental science , precipitation , atmospheric sciences , evapotranspiration , climatology , water cycle , geoengineering , atmosphere (unit) , climate model , aerosol , water content , climate change , moisture , meteorology , geography , geology , ecology , oceanography , geotechnical engineering , biology
Stratospheric sulfate aerosol geoengineering has been proposed as a potential strategy to reduce the impacts of climate change. Here we investigate the impact of stratospheric aerosol geoengineering on the terrestrial hydrological cycle. We use the Geoengineering Large Ensemble, which involves a 20‐member ensemble of simulations using the Community Earth System Model with the Whole Atmosphere Community Climate Model, in which sulfur dioxide (SO 2 ) was injected into the stratosphere at four different locations, to maintain global mean surface temperature, and also the interhemispheric and equator‐to‐pole temperature gradients at values representative of 2020 (“baseline”) under the Representative Concentration Pathway 8.5. In our simulations, annual mean land precipitation and evapotranspiration ( ET ) increase by 12% each under Representative Concentration Pathway 8.5. Under the Geoengineering Large Ensemble, the hydrological cycle is suppressed compared to the baseline, with end‐of‐century decreases of 1.4% (12 ± 5 mm/year) and 3.3% (18 ± 2 mm/year) in global mean, annual mean precipitation, and ET over land, respectively. Geoengineering effectively maintains global mean soil moisture under a high CO 2 scenario, although there is significant regional variability. Summertime soil moisture is reduced by 42 ± 11 kg/m 2 (3.5%) and 27 ± 16 kg/m 2 (2.1%) in India and the Amazon, respectively, which is dominated by the decrease in precipitation. We also compare these regional changes in soil moisture under the Geoengineering Large Ensemble with an equatorial‐only SO 2 injection case and find a similar sign in residual changes, although the magnitude of the changes is larger in the equatorial run.