The Caribbean and 1.5 °C: Is SRM an Option?

Abstract

The Caribbean, along with other small island developing states (SIDS), have advocated for restricting global warming to 1.5 °C above pre-industrial levels by the end of the current century. Solar radiation management (SRM) may be one way to achieve this goal. This paper examines the mean Caribbean climate under various scenarios of an SRM-altered versus an SRM-unaltered world for three global warming targets, namely, 1.5, 2.0 and 2.5 °C above pre-industrial levels. Data from the Geoengineering Model Intercomparison Project Phase 1 (GeoMIP1) were examined for two SRM scenarios: the G3 experiment where there is a gradual injection of sulfur dioxide (SO2) into the tropical lower stratosphere starting in 2020 and terminating after 50 years, and the G4 experiment where a fixed 5 Teragram (Tg) of SO2 per year is injected into the atmosphere starting in 2020 and ending after 50 years. The results show that SRM has the potential to delay attainment of the 1.5, 2.0 and 2.5 °C global warming targets. The extent of the delay varies depending on the SRM methodology but may be beyond mid-century for the 1.5 °C goal. In comparison, however, the higher temperature thresholds are both still attained before the end of century once SRM is ceased, raising questions about the value of the initial delay. The application of SRM also significantly alters mean Caribbean climate during the global warming target years (determined for a representative concentration pathway 4.5 (RCP4.5) world without SRM). The Caribbean is generally cooler but drier during the 1.5 °C years and similarly cool but less dry for years corresponding to the higher temperature targets. Finally, the mean Caribbean climate at 1.5 °C differs if the global warming target is achieved under SRM versus RCP4.5. The same is true for the higher warming targets. The implications of all the results are discussed as a background for determining whether SRM represents a viable consideration for Caribbean SIDS to achieve their “1.5 to stay alive” goal.

Stratospheric Sulfate Aerosols Impacts on West African Monsoon Precipitation Using GeoMIP Models

“…G3 is an SAG simulation based on the RCP4.5 scenario, with deployment starting in 2020 and gradually ramping‐up the amount of SO 2 or sulfate aerosol injected, to keep global average temperature nearly constant at 2020 levels (Kravitz et al., 2011). G4 is similar except that starting from 2020 it applies a constant injection of SO 2 at a rate of 5 Tg SO 2 per year (Bürger et al., 2015; Clarke et al., 2021; Kravitz et al., 2011). Both G3 and G4 inject SO 2 into the equatorial stratosphere at the altitude range of 16–25 km at 0° longitude on the equator.…”

Stratospheric Sulfate Aerosols impacts on West African monsoon precipitation using GeoMIP Models

“…G4 is a combination with RCP4.5. Starting from 2020, it requires continuous injection of SO2 through the lower stratosphere to the equator at a rate of 5 Tg SO2 per year (Kravitz et al, 2011, Bürger et al, 2015, Clarke et al, 2021. We used monthly RCP4.5 and G3 and G4 simulations, monthly historical P simulations of CMIP5 have been compared with the observations for model validation over 1986 and 2005.…”