Impacts of Timing and Level of Stratospheric Aerosol Injection on Coral Thermal Bleaching

Le résumé fourni par la source

Frequent and severe bleaching under global warming has resulted in widespread coral mortality and decline across the globe. To prevent further decline of reefs, warming needs to be limited to 1.5℃ or below, which requires rapid emission reduction that is yet to be achieved. Solar climate intervention (SCI) is being considered as a supplement to emission reductions and other risk mitigation strategies to prevent exceeding climate tipping points. However, there is a crucial need to investigate impacts to ecosystems to inform scenario development and decision-making. Here, we use daily sea surface temperature (SST) data from the Community Earth System Model simulations to project and compare thermal coral bleaching under a moderate emissions scenario, SSP2-4.5, with and without intervention using stratospheric aerosol injection (SAI). To understand the impact of temperature targets and timing of deployment on coral thermal bleaching, we use three SAI scenarios: SAI-1.0, starting in 2035 and limiting warming to 1.0℃, SAI-1.5, starting in 2035 and limiting warming to 1.5℃, and SAI-Delayed starting in 2045 and limiting warming to ~1.37℃. We found that under all three SAI scenarios, global reef provinces experience significantly lower levels of thermal stress relative to SSP2-4.5. Among the three intervention scenarios, SAI limiting warming to 1.0℃ in 2035 most effectively mitigates thermal bleaching over space and time.

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