The stabilizing effect of geoengineering on the Atlantic Overturning Circulation

Abstract

Solar radiation management has been proposed to enhance earth’s albedo and reduce the amount solar radiation retained by the earth. Here we analyse the effects of the strategic injection of sulphate aerosols into the stratosphere on one of the ocean ’s large scale circulations. The aerosols are injected at four strategic locations (30o, 15o in both hemispheres) to minimize the future change in the global mean temperature and the temperature gradients between hemispheres and from equator-to-pole. The approach is successful at keeping the temperature goals at the predefined 2020 levels of the RCP 8.5 scenario. This means some adverse effects of solar radiation management, like the ’over cooling of the equatorial region are reduced compared to previous studies. However, feedbacks from surface fluxes cause a strengthening of the Atlantic Meridional Overturning Circulation (AMOC) under the injection of sulphate aerosols compared to a warming climate under a RCP 8.5 scenario. How and what exactly causes this difference in strength and stability of the AMOC is critical for our understanding of the complete response of the climate. The understanding of the shifts in the strength and stability of the AMOC is important because of the role the AMOC played in some of the largest shifts in the global Paleoclimate. Studying the simulations of the geoengineering large ensemble project gives us new insights in the strength and stability of the ocean’s circulation, but also highlights the fact that we need more research in the climate’s response to geoengineering strategies before implementation is a viable option to reduce the global temperature.