Impact of stratospheric aerosol injection on thermal environment shift

In this study, we applied the monthly mean near-surface temperatures from the historical and future projections under the SSP585 and G6 sulfur scenarios. The bias-correction and multi-model ensemble averaging were applied to the monthly mean near-surface temperatures from four models and then used to investigate the impact of Stratospheric Aerosol Injection (SAI) on species migration to thermal environments similar to their historical adaptations. Thermal connectivity was used to quantify the migration capacity, with thermal exposure (TE) representing the cumulative temperature difference (°C) along the migration path and thermal velocity (TV) characterizing the minimum migration velocity (km yr⁻¹) required for species to track their historically adapted thermal environments. The results show that SAI exhibits a complex dual effect under the SSP585 scenario. SAI can successfully mitigate thermal stress in more than 80% global land area and provide an additional about 2% of the migratory zone globally. The mitigation effect was most significant in high-latitude regions. On the other hand, implementing SAI under the SSP585 scenario can lead to increased thermal stress in 4% of the land area increasing migration pressure in these regions. The results highlight that temperature response of SAI exhibits heterogeneous impact on thermal environments, necessitating the development of customized adaptation strategies tailored to different geographical regions in the future.