Would solar radiation modification reduce the adaptation burden from shifting climate zones?

Presentation given at the Degrees Global Forum in Cape Town, South Africa, on 15 May 2025 in the Impacts Modelling 2 session, based on work by then-FSU undergraduate student Jaylynn Brunelli.

Transcript

1. Would solar radiation modification reduce the adaptation burden from shifting climate zones? Jaylynn Brunelli & Michael Diamond (msdiamond@fsu.edu) Department of Earth, Ocean, and Atmospheric Science Florida State University, Tallahassee, USA Degrees Global Forum: Impacts Modelling 2 Cape Town, South Africa // 15 May 2025
2. Jay Brunelli (will be looking for graduate advisors soon!)
3. Köppen (1900)
4. Tropical Arid Subtropical Temperate (Sub)polar
5. Present-day distribution of climate zones
6. Expectation under high GHG emissions ?
7. Expectation under low GHG emissions ?
8. Expectation under high GHG emissions + SRM? ?
9. Expectation under high GHG emissions + SRM?
10. SRM could (a) successfully cool temperatures from a high greenhouse gas (GHG) emissions scenario to a lower GHG one… …but it would • (b) “overcorrect” precipitation; and • (c) not stop ocean acidification High GHGs Lower GHGs SAI + high GHGs Diamond, Wanser, & Boucher (2023), “Cooling credits” are not a viable climate solution, Climatic Change
11. Approach • G6sulfur experiment in CESM2-WACCM • Equatorial SO2 injection to keep climate with high SSP58.5 greenhouse gas emissions near same mean temperature as under “middle-of-the-road” SSP2-4.5 emissions
12. Approach • G6sulfur experiment in CESM2-WACCM • Köppen-Trewartha climate classification system Lohmann et al. (1994), The Köppen climate classification as a diagnostic tool for general circulation models, Climate Research
13. Approach • G6sulfur experiment in CESM2-WACCM • Köppen-Trewartha climate classification system • Hypotheses: 1. Stratospheric aerosol injection will reduce shifts in climate zones similar to mitigation of GHGs (i.e., broadly as a function of reduced global mean surface temperature) • SAI “works” to reduce the adaptation burden from shifting climate zones 2. Stratospheric aerosol injection will result in shifts in climate zones rivaling those in SSP5-8.5, but non-systematically in temperature (regional variability) and systematically dryer (lower precipitation) • SAI does not “work” to reduce the adaptation burden from shifting climate zones
14. B: Arid A: Trop. C: Subtrop. D: Temp. E-F: Sub- Polar
15. Cold arid Cold semi-arid Hot arid Hot semi-arid B: Arid Class B: Arid Precipitation below potential evapotranspiration A: Trop. C: Subtrop. D: Temp. E-F: Sub- Polar
16. Class A: Tropical All months warmer than 18 °C Rainforest Savanna B: Arid A: Trop. C: Subtrop. D: Temp. E-F: Sub- Polar
17. Subtropical humid Mediterranean Class C: Subtropical >8 months warmer than 10 °C B: Arid A: Trop. C: Subtrop. D: Temp. E-F: Sub- Polar
18. Temperate continental Temperate oceanic Class D: Temperature >4 months warmer than 10 °C B: Arid A: Trop. C: Subtrop. D: Temp. E-F: Sub- Polar
19. Subpolar Class E: Subpolar >1 month warmer than 10 °C B: Arid A: Trop. C: Subtrop. D: Temp. E-F: Sub- Polar
20. Tundra Class F: Polar No months warmer than 10 °C Ice cap (no months above freezing) B: Arid A: Trop. C: Subtrop. D: Temp. E-F: Sub- Polar
21. B: Arid A: Trop. C: Subtrop. D: Temp. E-F: Sub- Polar
22. Hotter than hottest individual month at present!
23. “Novel” tropics Hotter than hottest individual month at present! “Novel” arid
24. Hotter than hottest individual month at present!
27. Hypotheses: 1. Stratospheric aerosol injection will reduce shifts in climate zones similar to mitigation of GHGs (i.e., broadly as a function of reduced global mean surface temperature) • SAI “works” to reduce the adaptation burden from shifting climate zones 2. Stratospheric aerosol injection will result in shifts in climate zones rivaling those in SSP5-8.5, but non-systematically in temperature (regional variability) and systematically dryer (lower precipitation) • SAI does not “work” to reduce the adaptation burden from shifting climate zones