My impression is that it is the area of the cloud free subtropical high pressure cells of
descending air that is a strong variable factor explaining the change in the temperature of the in - feed waters that become the westerly
currents that occupy the tropical latitudes.
The Planet Remade covers all the main proposed geoengineering techniques --(not just SAI, but also ocean iron fertilization (OIF), marine cloud brightening (MCB), bioenergy with carbon capture and storage (BECCS) and direct
air capture (DAC)-RRB-, outlining their history, the
current state of knowledge, and expected risks and benefits (and impressively, without
descending into the alphabet soup of all these acronyms).