Soil moisture and other hydrological changes in a stratospheric aerosol geoengineering large ensemble

[Andrew Lockley]

Poster's note: I'd be interested to see how this affects vegetation changes and the spread of fire in the amazon 

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JD030237

Journal of Geophysical Research: AtmospheresAccepted Articles

Research Article

Soil moisture and other hydrological changes in a stratospheric aerosol geoengineering large ensemble

Wei Cheng Douglas G. MacMartin Katherine Dagon Ben Kravitz Simone Tilmes … See all authors 

First published: 13 September 2019

https://doi.org/10.1029/2018JD030237

This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1029/2018JD030237

About

 

Share on

Abstract

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 (GLENS), 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 (SO2) 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 (RCP8.5). In our simulations, annual mean land precipitation and evapotranspiration (ET) increase by 12% each under RCP8.5. Under GLENS, the hydrological cycle is suppressed compared to the baseline, with end‐of‐century decreases of 1.4% (12±5 mm year‐1) and 3.3% (18±2 mm year‐1) in global mean, annual mean precipitation and ET over land, respectively. Geoengineering effectively maintains global mean soil moisture under a high CO2 scenario, though 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 GLENS with an equatorial‐only SO2 injection case and find a similar sign in residual changes, although the magnitude of the changes is larger in the equatorial run.

Key Points

In our simulations, geoengineering effectively maintains global mean soil moisture under a high CO2 scenario, but some regional changes remain

Summertime soil moisture is reduced in India and the Amazon under geoengineering; this change is dominated by the change in precipitation

Geoengineering using multiple injection locations yields smaller magnitude of the changes in soil moisture than equatorial‐only injection