Supplementary file 1_Pathway-dependent responses of temperature extremes under solar radiation modification over Northern Africa.pdf

Project

Phase 6 (CMIP6) and Geoengineering Model Intercomparison

Project

Phase 6 (GeoMIP6). Changes are evaluated for near-future (2020–2054) and far-future (2065–2099) periods, integrating spatial patterns, temporal evolution, distributional shifts, and extreme-mean relationships. Asymmetry diagnostics are further applied to assess differences between warm–cold and day–night responses.

Results show that SRM suppresses the intensification of warm temperature extremes relative to SSP5-8.5. However, despite achieving similar mean temperature, SRM does not reproduce the behaviour of temperature extremes under SSP2-4.5. Frequency-based indices exhibit the strongest divergence, particularly in the far-future, with more frequent warm extremes and fewer cold events under SRM compared with the intermediate-emission pathway.

The relationship between extreme and mean temperature is approximately linear but varies across scenarios, with differences in sensitivity and spread indicating forcing-dependent relationship. In addition, SRM modifies the structure of temperature extremes, with an asymmetric response of upper and lower tails and smaller differences between daytime and night-time extremes, leading to a redistribution of the temperature distribution rather than a uniform shift.

These results suggest that reducing global mean temperature does not fully restore the behaviour of temperature extremes. Instead, SRM produces a distinct, scenario-dependent climate that differs from both high- and intermediate-emission pathways. This highlights the need to assess climate intervention strategies using metrics that capture both mean conditions and the distribution and structure of extremes.</p>