https://www.researchgate.net/publication/356378673_Climate_Impact_of_Decreasing_Atmospheric_Sulphate_Aerosols_and_the_Risk_of_a_Termination_Shock
November 2021 Authors: Leon Simons, James E. Hansen, Yann Dufournet DOI:10.13140/RG.2.2.22778.62408 Abstract Significant reduction in atmospheric sulphate aerosols contributes to albedo reduction, acceleration in Earth’s Heating Rate and could cause an aerosol termination shock. Recent SOx emission reductions are realized for health and environmental regulation through conversion to low sulphur fuels and the use of desulphurization systems. The most immediate SOx reduction is of shipping with ~90% in Emission Control Areas (ECAs) from Jan 1st, 2015 and ~80% globally from Jan 1st, 2020, through sulphur fuel content regulation from the International Maritime Organization (IMO 2020), with Low Sulphur Fuel Oil (LSFO) sales indicating global SOx reduction started in Oct 2019. Aerosols and aerosol-cloud interactions are the most significant uncertainty of the anthropogenic climate impact. Aerosols have a cooling effect on the climate through increased scattering of solar radiation to space and by acting as cloud condensation nuclei, increasing cloud cover, affecting cloud lifetime and regional and global albedo. The SOx emission reduction provides a real-world research opportunity of the effects, constrained by the availability of measurements and data. In this study, we review modelling studies on the effects of decreased SOx emissions, combined with assessments of actually realised emission reductions and changes in the Earth Energy Imbalance (EEI) and albedo, based on Ocean Heat Content, CERES and Earthshine. Here we show that the global and regional reduction in albedo14 and increase in EEI2 coincides with a significant reduction in anthropogenic SOx emissions and an increase in the net positive anthropogenic forcing on the Earth system3. CERES TOA EEI trend in Absorbed Solar Radiation (ASR) shows a factor of 4 increase after 2014 compared to prior to 2014, which is attributed to cloud changes from a positive PDO index4. Modelling studies however indicate significant regional forcing changes from shipping SOx mitigation in the region showing the strongest ASR increase, the northeast Pacific Ocean56. Even stronger global forcing effects are expected from IMO 2020, with models showing ERF in a range of 0.027 W/m² (7DRE & AIE) to 0.36 W/m² (5AIE only). Total aerosol ERF of -1.3 [-2.0 to -0.6] W/m² from 1750-2014 changed to -1.1 [1.7 to -0.4] W/m² over 1750-20193. Here we argue that further decrease in negative aerosol ERF is highly likely and could increase the EEI. The possibility of a termination shock, whereby rapid anthropogenic aerosol emission reductions cause rapid global warming, cannot be excluded. Source: ResearchGate -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/CAOyeF5v7f-QcK%2BPTDE6XOjX7NOi-KXNeODQDSL6DndUBmDmk2Q%40mail.gmail.com.
