Abstract
Earth system modeling of climate geoengineering proposals suggests that
the physical outcomes of such interventions will depend on the
particulars of the implementation. Here, we present a first attempt to
“geoengineer” a well-known teleconnection between sea surface
temperatures (SSTs) and Sahelian precipitation. Using idealized earth
system model simulations, we show that selectively cooling the Indian
Ocean efficiently increases precipitation in the Sahel region, widening
the seasonally migrating rainband over Africa. Applying the SST
perturbations derived from the idealized experiments to observationally
constrained historical ones, we find that our intervention can reverse
conditions as extreme as the mid-20th century Sahelian
drought, albeit less efficiently than in the idealized simulations. Side
effects include changes in the seasonal distribution of Sahelian
precipitation and substantial precipitation reductions in sub-Saharan
East Africa. This work represents a proof-of-concept illustration of
effects that might be expected with a tailored, regional approach to
climate intervention.