Publication Date:
2023-09-29
Description:
Volcanic aerosol forcing has previously been found to cause a weak global mean temperature response, compared with CO2 radiative forcing of equal magnitude: its efficacy is supposedly low. We explore this phenomenon in the framework of the pattern effect: Radiative feedback is a function of SST patterns, which evolve over time. In particular, the SST in the Indo-Pacific warm pool region (30°S–30°N, 50°E–160°W) control the global radiative feedback, because this region has strong local and remote effects on lapse rates and cloudiness. Using idealized coupled model simulations, we show that stratospheric sulfate aerosol forcing initially preferentially cools the warm pool region. This enhanced temperature change in the warm pool actuates strong feedbacks, both local and remote. Strong feedbacks imply a weak temperature change for a given forcing. However, when keeping the aerosol field fixed, the SST pattern changes from warm-pool-focused to non-warm-pool-focused when transitioning from the decadal to the centennial time scale, accompanied by a weakened feedback. The results for the short time scale explain the low efficacy of volcanic eruptions for changing the global mean temperature, while the results for the longer time scales have implications for geoengineering scenarios.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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