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Title: Impact of solar geoengineering on wildfires in the 21st century in CESM2/WACCM6

Abstract. We quantify future changes in wildfire burned area and carbon emissions inthe 21st century under four Shared Socioeconomic Pathways (SSPs) scenariosand two SSP5-8.5-based solar geoengineering scenarios with a target surfacetemperature defined by SSP2-4.5 – solar irradiance reduction (G6solar) andstratospheric sulfate aerosol injections (G6sulfur) – and explore themechanisms that drive solar geoengineering impacts on fires. This study isbased on fully coupled climate–chemistry simulations with simulatedoccurrence of fires (burned area and carbon emissions) using the WholeAtmosphere Community Climate Model version 6 (WACCM6) as the atmosphericcomponent of the Community Earth System Model version 2 (CESM2). Globally,total wildfire burned area is projected to increase over the 21st centuryunder scenarios without geoengineering and decrease under the twogeoengineering scenarios. By the end of the century, the two geoengineeringscenarios have lower burned area and fire carbon emissions than not onlytheir base-climate scenario SSP5-8.5 but also the targeted-climate scenarioSSP2-4.5. Geoengineering reduces wildfire occurrence by decreasing surfacetemperature and wind speed and increasing relative humidity and soil water,with the exception of boreal regions where geoengineering increases theoccurrence of wildfires due to a decrease in relative humidity and soilwater compared with the present day. This leads to a global reduction in burnedarea and fire carbon emissions by the end of the century relative to theirbase-climate scenario SSP5-8.5. However, geoengineering also yieldsreductions in precipitation compared with a warming climate, which offsetssome of the fire reduction. Overall, the impacts of the different drivingfactors are larger on burned area than fire carbon emissions. In general,the stratospheric sulfate aerosol approach has a stronger fire-reducingeffect than the solar irradiance reduction approach.

 
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Award ID(s):
2028541 2017113
PAR ID:
10476087
Author(s) / Creator(s):
; ; ; ; ; ; ;
Publisher / Repository:
Copernicus Publications
Date Published:
Journal Name:
Atmospheric Chemistry and Physics
Volume:
23
Issue:
9
ISSN:
1680-7324
Page Range / eLocation ID:
5467 to 5486
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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