Scripts and Datasets for "Impacts of Timing and Intensity of Stratospheric Aerosol Injection on Coral Reefs"

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. SCI does not mitigate the intensifying ocean acidification, associated with high CO2. There is a crucial need to investigate impacts of SCI 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 bleaching under a moderate emissions scenario, SSP2-4.5, with and without intervention using stratospheric aerosol injection (SAI). To understand the impact of timing and intensity of SAI on bleaching, we analyze 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℃. For ocean acidification, we assess patterns in aragonite saturation state (Ωarag) under SSP2-4.5 and SAI-1.5. Across all three SAI scenarios, global reef provinces are projected to experience notably less thermal stress than under SSP2-4.5, with SAI-1.0 providing the greatest reduction in bleaching risk over space and time. Ocean acidification, however, remains a threat, and SAI-1.5 is projected to have lower Ωarag than SSP2-4.5.