Climate speeds help frame relative ecological risk in future climate change and stratospheric aerosol injection scenarios

Abstract

Stratospheric aerosol injection (SAI) is a potential method of climate intervention to reduce climate risk as decarbonization efforts continue. Two recent Earth system modeling experiments depict policy-relevant SAI scenarios with similar temperature targets (near 1.5°C), but with deployment delayed by 10 years between experiments. This relatively short delay leads to highly distinct profiles of ecological risk from climate speeds. Climate speeds when global temperature is maintained with SAI are indistinguishable on a planetary scale from those experienced under preindustrial conditions. In contrast, the delayed SAI deployment produces very large climate speeds far beyond natural variability and robustly greater in magnitude over land than no-SAI climate change with present policy. Examining the global area exposed to threshold climate speeds facilitates evaluation of relative ecological risk among future climate scenarios. Our results support discussion of tradeoffs and timescales in future climate intervention scenario design and decision-making.

Carbon Cycle Response to Stratospheric Aerosol Injection With Multiple Temperature Stabilization Targets and Strategies

“…The carbon cycle response in Figure 2 shows a smooth transition toward the longer-term behavior without any unexpected transient. Nonetheless, this rate of cooling (0.5°C or 1°C per decade) is rapid compared to current rates of warming and could have ecological consequences (Hueholt et al, 2024); these may not be accurately represented in this climate model.…”