Marine Cloud Brightening and Precipitation Responses in the Tropical Pacific Ocean - Preprint

[Geoengineering News]

https://essopenarchive.org/doi/full/10.22541/essoar.15005398/v1

Authors: Dr. Pornampai Narenpitak, Siriwat Kongkulsiri, Dr. Saifhon Tomkratoke, Dr. Haruki Hirasawa, Mr. Alex Mulligan Mason, Matthew Henry, and Sirod Sirisup

29 June 2026

Primary Abstract

Increased anthropogenic greenhouse gas emissions have driven sustained global temperature rise, which is projected to continue through the 21st century even under an intermediate-emission scenario (SSP2-4.5). Marine cloud brightening (MCB) has been proposed to temporarily offset this warming. We analyze existing simulations from three Earth System Models (CESM2, E3SMv2, and UKESM1) that implemented MCB across 16 regions to evaluate how regional radiative forcing due to low cloud albedo increases drives remote climate responses in the tropics. The Southeast and South Pacific emerge as the most effective intervention zones, with MCB in this region inducing the strongest global cooling and highlighting the tropical Pacific’s high sensitivity to intervention location. Specifically, MCB applied in one hemisphere leads to spatially uneven cooling, which modulates interhemispheric temperature gradients, shifting the Intertropical Convergence Zone toward the hemisphere with less cooling. For a given oceanic basin, mid-latitude intervention generally produces stronger responses than lower-latitude subtropical intervention. MCB intervention in the subtropics also influences zonal circulation by reorganizing the Walker circulation over the Pacific Ocean. Subtropical eastern Pacific MCB leads to La Niña-like temperature response patterns, while Southeast and South Atlantic MCB produces surface temperature patterns resembling an El Niño-like state in the Pacific; both patterns subsequently affect the tropical precipitation distribution. These findings demonstrate there are important teleconnections that drive remote effects from local MCB on the wider tropics beyond a given intervention region.

Source: ESS Open Archive