
For this figure, the increase in sulfate comes from “historical” (1850-2015) runs of the latest generation of state-of-the-art climate models (CMIP6) and the ERFaci is estimated using cloud-aerosol relationships derived from an analysis of a shipping corridor in the southeast Atlantic Ocean. For reference, the radiative forcing today from increasing atmospheric greenhouse gas concentrations is ~3 W/m2.
For more information, check out our (open-access!) paper in AGU Advances:
Diamond, Michael, H. Director, R. Eastman, A. Possner, & R. Wood (2020). Substantial Cloud Brightening from Shipping in Subtropical Low Clouds. AGU Advances, 1(1), e2019AV000111. doi:10.1029/2019av000111