Regional response of land hydrology and carbon uptake to different amounts of solar radiation modification

[ayesha iqbal]

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2022EF003288

Mengying Zhao,Long Cao

First published: 11 November 2022

https://doi.org/10.1029/2022EF003288

Abstract

Solar radiation modification (SRM) is a proposed method to cool the Earth by intentionally perturbing the Earth's energy balance. One concern about the effect of SRM is disparities in the regional climate response. In this study, we use the Community Earth System Model (CESM1.2) to analyze the regional response of land hydrology and terrestrial carbon uptake to different amounts of SRM. The SRM is implemented by a uniform increase in volcanic-size sulfate aerosols in the stratosphere under a doubling of atmospheric CO2. Our results show that different amounts of SRM could either moderate or exacerbate CO2-induced changes in land hydrology including precipitation, precipitation minus evapotranspiration, and soil moisture (SM), but the effect varies widely across regions and specific variables. An “optimal” amount of SRM that moderates land hydrology changes for one region might exacerbate changes for other regions (or vice versa). Also, our study shows that for quite a few regions, partial SRM moderates CO2-induced change in precipitation minus evaporation but exacerbates changes in CO2-induced SM. The response of terrestrial Net primary productivity (NPP) to different amounts of SRM shows large regional disparities, depending on whether temperature or water availability constrains NPP more. Our study also shows that the effect of CO2 physiological forcing plays a key role in regulating land hydrology response to SRM, especially at the regional scale.

Key Points

We use the Community Earth System Model model to analyze how different amounts of solar radiation modification (SRM) affect regional climate

Land hydrology response depends on the amount of SRM, the region, and the specific variables considered

The response of land productivity to different amounts of SRM is regionally dependent

Plain Language Summary

To reduce anthropogenic global warming, different solar radiation modification (SRM) approaches have been proposed. One main concern about the climate effect of SRM is the uneven regional climate response. We use a climate model to analyze how stratospheric aerosol increase would affect regional climate. Our focus is on regional land hydrology (including precipitation, precipitation minus evapotranspiration, and soil moisture [SM]) and carbon cycle response to different intensities of stratospheric aerosol increase. Our results demonstrate that different intensities of aerosol increase would induce strong regional inequalities in reducing the CO2-induced anomaly of specific quantities. A certain intensity of SRM that reduces the CO2-induced anomaly of land hydrology for one region might increase the anomaly for other regions. In some regions, SRM reduces the CO2-induced anomaly in precipitation minus evapotranspiration but increases the CO2-induced anomaly in SM. In addition, changes in vegetation productivity in response to different intensities of SRM show large regional disparities, depending on whether temperature or water availability is the major limiting factor for vegetation growth.

Source: Earth's futures