Global and regional thermosteric and dynamic sea level change under stratospheric aerosol injection

Sea level rise (SLR) is a global concern in the era of climate change, prompting the exploration of interventions such as solar radiation modification through stratospheric aerosol injection (SAI). This intervention could affect the physical system in various ways. The present study analyzes the global and regional impacts of SAI using ARISE-SAI-1.5 (SAI-1.5) simulations with the Community Earth System Model 2. We calculated the regional thermosteric sea level under different scenarios. After validating our methodology for sea level components over the period 1995–2014, we determined changes in sea level variables under both SAI-1.5 and the underlying Shared Socioeconomic Pathway 2–4.5 (SSP2-4.5) relative to the reference period (1995–2014). In contrast to sea surface temperature, which under this SAI strategy should be maintained near 1.5 °C above preindustrial values, global SLR would continue increasing under SAI-1.5. However, SAI would significantly impact thermal expansion in SSP2-4.5 simulations, reducing the global long-term sea level trend from 3.7 ± 0.03 mm yr⁻¹ for SSP2-4.5–1.9 ± 0.04 mm yr⁻¹ for SAI-1.5, a 49% reduction. The associated ocean heat content is reduced from (2.0 ± 0.3) × 10²² J yr⁻¹ under SSP2-4.5 to (1.17 ± 0.30) × 10²² J yr⁻¹ under SAI, a 42% reduction. Additionally, SAI would impact the regional and global ocean by reducing the SLR rate. These findings underscore the potential of SAI as a climate intervention strategy with significant implications for sea level change.