Overlooked Long‐Term Atmospheric Chemical Feedbacks Alter the Impact of Solar Geoengineering: Implications for Tropospheric Oxidative Capacity
Abstract Studies of the impacts of solar geoengineering have mostly ignored tropospheric chemistry. By decreasing the sunlight reaching Earth's surface, geoengineering may help mitigate anthropogenic climate change, but changing sunlight also alters the rates of chemical reactions throughout th...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2023-10-01
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| Series: | AGU Advances |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2023AV000911 |
| _version_ | 1797649174969188352 |
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| author | Jonathan M. Moch Loretta J. Mickley Sebastian D. Eastham Elizabeth W. Lundgren Viral Shah Jonathan J. Buonocore Jacky Y. S. Pang Mehliyar Sadiq Amos P. K. Tai |
| author_facet | Jonathan M. Moch Loretta J. Mickley Sebastian D. Eastham Elizabeth W. Lundgren Viral Shah Jonathan J. Buonocore Jacky Y. S. Pang Mehliyar Sadiq Amos P. K. Tai |
| author_sort | Jonathan M. Moch |
| collection | DOAJ |
| description | Abstract Studies of the impacts of solar geoengineering have mostly ignored tropospheric chemistry. By decreasing the sunlight reaching Earth's surface, geoengineering may help mitigate anthropogenic climate change, but changing sunlight also alters the rates of chemical reactions throughout the troposphere. Using the GEOS‐Chem atmospheric chemistry model, we show that stratospheric aerosol injection (SAI) with sulfate, a frequently studied solar geoengineering method, can perturb tropospheric composition over a span of 10 years, increasing tropospheric oxidative capacity by 9% and reducing methane lifetime. SAI decreases the overall flux of shortwave radiation into the troposphere, but increases flux at certain UV wavelengths due to stratospheric ozone depletion. These radiative changes, in turn, perturb tropospheric photochemistry, driving chemical feedbacks that can substantially influence the seasonal and spatial patterns of radiative forcing beyond what is caused by enhanced stratospheric aerosol concentrations alone. For example, chemical feedbacks decrease the radiative effectiveness of geoengineering in northern high latitude summer by 20%. Atmospheric chemical feedbacks also imply the potential for net global public health benefits associated with stratospheric ozone depletion, as the decreases in mortality resulting from SAI‐induced improvements in air quality outweigh the increases in mortality due to increased UV radiation exposure. Such chemical feedbacks also lead to improved plant growth. Our results show the importance of including fuller representations of atmospheric chemistry in studies of solar geoengineering and underscore the risk of surprises from this technology that could carry unexpected consequences for Earth's climate, the biosphere, and human health. |
| first_indexed | 2024-03-11T15:42:29Z |
| format | Article |
| id | doaj.art-bbc6c6227d784fc680073b73b6f8026e |
| institution | Directory Open Access Journal |
| issn | 2576-604X |
| language | English |
| last_indexed | 2024-03-11T15:42:29Z |
| publishDate | 2023-10-01 |
| publisher | Wiley |
| record_format | Article |
| series | AGU Advances |
| spelling | doaj.art-bbc6c6227d784fc680073b73b6f8026e2023-10-26T11:48:29ZengWileyAGU Advances2576-604X2023-10-0145n/an/a10.1029/2023AV000911Overlooked Long‐Term Atmospheric Chemical Feedbacks Alter the Impact of Solar Geoengineering: Implications for Tropospheric Oxidative CapacityJonathan M. Moch0Loretta J. Mickley1Sebastian D. Eastham2Elizabeth W. Lundgren3Viral Shah4Jonathan J. Buonocore5Jacky Y. S. Pang6Mehliyar Sadiq7Amos P. K. Tai8John A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge MA USAJohn A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge MA USALaboratory for Aviation and the Environment Department of Aeronautics and Astronautics Massachusetts Institute of Technology Cambridge MA USAJohn A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge MA USAJohn A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge MA USACenter for Climate, Health, and the Global Environment T.H. Chan School of Public Health Harvard University Boston MA USAInstitute of Environment, Energy and Sustainability The Chinese University of Hong Kong Sha Tin Hong KongInstitute of Environment, Energy and Sustainability The Chinese University of Hong Kong Sha Tin Hong KongInstitute of Environment, Energy and Sustainability The Chinese University of Hong Kong Sha Tin Hong KongAbstract Studies of the impacts of solar geoengineering have mostly ignored tropospheric chemistry. By decreasing the sunlight reaching Earth's surface, geoengineering may help mitigate anthropogenic climate change, but changing sunlight also alters the rates of chemical reactions throughout the troposphere. Using the GEOS‐Chem atmospheric chemistry model, we show that stratospheric aerosol injection (SAI) with sulfate, a frequently studied solar geoengineering method, can perturb tropospheric composition over a span of 10 years, increasing tropospheric oxidative capacity by 9% and reducing methane lifetime. SAI decreases the overall flux of shortwave radiation into the troposphere, but increases flux at certain UV wavelengths due to stratospheric ozone depletion. These radiative changes, in turn, perturb tropospheric photochemistry, driving chemical feedbacks that can substantially influence the seasonal and spatial patterns of radiative forcing beyond what is caused by enhanced stratospheric aerosol concentrations alone. For example, chemical feedbacks decrease the radiative effectiveness of geoengineering in northern high latitude summer by 20%. Atmospheric chemical feedbacks also imply the potential for net global public health benefits associated with stratospheric ozone depletion, as the decreases in mortality resulting from SAI‐induced improvements in air quality outweigh the increases in mortality due to increased UV radiation exposure. Such chemical feedbacks also lead to improved plant growth. Our results show the importance of including fuller representations of atmospheric chemistry in studies of solar geoengineering and underscore the risk of surprises from this technology that could carry unexpected consequences for Earth's climate, the biosphere, and human health.https://doi.org/10.1029/2023AV000911geoengineeringsolar radiation managementstratospheric aerosol injectionclimateatmospheric chemistrypublic health |
| spellingShingle | Jonathan M. Moch Loretta J. Mickley Sebastian D. Eastham Elizabeth W. Lundgren Viral Shah Jonathan J. Buonocore Jacky Y. S. Pang Mehliyar Sadiq Amos P. K. Tai Overlooked Long‐Term Atmospheric Chemical Feedbacks Alter the Impact of Solar Geoengineering: Implications for Tropospheric Oxidative Capacity AGU Advances geoengineering solar radiation management stratospheric aerosol injection climate atmospheric chemistry public health |
| title | Overlooked Long‐Term Atmospheric Chemical Feedbacks Alter the Impact of Solar Geoengineering: Implications for Tropospheric Oxidative Capacity |
| title_full | Overlooked Long‐Term Atmospheric Chemical Feedbacks Alter the Impact of Solar Geoengineering: Implications for Tropospheric Oxidative Capacity |
| title_fullStr | Overlooked Long‐Term Atmospheric Chemical Feedbacks Alter the Impact of Solar Geoengineering: Implications for Tropospheric Oxidative Capacity |
| title_full_unstemmed | Overlooked Long‐Term Atmospheric Chemical Feedbacks Alter the Impact of Solar Geoengineering: Implications for Tropospheric Oxidative Capacity |
| title_short | Overlooked Long‐Term Atmospheric Chemical Feedbacks Alter the Impact of Solar Geoengineering: Implications for Tropospheric Oxidative Capacity |
| title_sort | overlooked long term atmospheric chemical feedbacks alter the impact of solar geoengineering implications for tropospheric oxidative capacity |
| topic | geoengineering solar radiation management stratospheric aerosol injection climate atmospheric chemistry public health |
| url | https://doi.org/10.1029/2023AV000911 |
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