Targeted marine cloud brightening can dampen El Ni\~no

TL;DR

This study investigates how targeted marine cloud brightening could mitigate extreme climate events like El Niño by restoring neutral ENSO conditions, potentially reducing climate variability impacts.

Contribution

It demonstrates that simulated marine cloud brightening can reproduce observed cloud changes and modulate ENSO events, offering a novel approach to climate risk mitigation.

Findings

Cloud brightening induces La Niña-like responses.

Timing and duration of interventions are critical.

Early and prolonged interventions effectively dampen El Niño.

Abstract

Many record-breaking climate extremes arise from both greenhouse gas-induced warming and natural climate variability. Marine cloud brightening, a solar geoengineering strategy originally proposed to reduce long-term warming, could potentially mitigate extreme events by instead targeting seasonal phenomena, such as El Ni\~no-Southern Oscillation (ENSO). By exploiting the 2019-2020 Australian wildfire experiment-of-opportunity, we show that simulated marine cloud brightening in the southeast Pacific reproduces observed cloud changes and induces La Ni\~na-like responses. We then explore how cloud brightening timing and duration modifies the 1997-1998 and 2015-2016 El Ni\~no events. We find the earliest and longest interventions effectively restore neutral ENSO conditions and dampen El Ni\~no's impacts. Solar geoengineering that targets climate variability could complement tools such as ENSO forecasting and provide a pathway for climate risk mitigation.