A modeling study proposes that marine cloud brightening could reduce warming from a developing super El Niño in the eastern Pacific. Researchers simulated the approach on past events and found it could halve temperature spikes. The method would require spraying seawater from thousands of ships.
The El Niño phase develops when easterly winds weaken, allowing warm water to move across the central and eastern Pacific. This raises global temperatures and can cause trillions of dollars in economic losses.
Jessica Wan at the University of California, San Diego, led the study published in Science Advances. Her team modeled marine cloud brightening on the 1997-1998 and 2015-2016 super El Niño events. Nine months of spraying would have cut Niño 3.4 region warming from over 2°C to about 1°C and ended the events by January.
The approach uses ships to spray seawater droplets below stratocumulus clouds, making them reflect more sunlight. It would need an estimated 2400 ships, beyond current nozzle technology limits.
Mat Collins at the University of Exeter warned that real-world cloud feedback could require more aerosol injection than the model showed. The study also noted risks of stronger subsequent La Niña phases affecting regions like the Horn of Africa.