Scientists model aerosol cooling for marine heatwaves [1]

Researchers led by Dr Lala Kounta used the ARISE-SAI simulator to test whether releasing reflective sulfur dioxide aerosols into the stratosphere could limit ocean heatwaves.[1] Their modelling found that annual injections of up to 11 million tons could reduce heatwave intensity by 25% and duration by 21%, while up to 22 million tons produced larger modelled reductions of 75% and 80%, respectively.[1] Why it matters: Marine heatwaves are associated with coral bleaching, declining marine species and toxic algal blooms, but aerosol cooling would not prevent oceans from absorbing carbon dioxide or stop acidification, leaving emissions cuts and carbon removal necessary.[1] Key insights: Stratospheric aerosol injection seeks to reflect sunlight using chemistry resembling the cooling effect observed after major volcanic eruptions.[1] | The 1991 Mount Pinatubo eruption released an estimated 22 million tons of sulfur dioxide and was followed by a global temperature decline of more than 1 degree Fahrenheit for nearly two years.[1] | The largest modelled benefits appeared in the tropical Atlantic, Indian Ocean, Arctic Ocean and South Atlantic.[1] | Most simulated aerosol deposition occurred in the Southern Hemisphere, where the broader atmospheric effects remain unclear.[1] Cheatsheet facts: What changed: A peer-reviewed simulation quantified potential reductions in marine heatwave intensity and duration under two sulfur dioxide injection scenarios.[1] | Why now: Record ocean warmth and worsening marine heatwaves are increasing risks to reefs, fisheries and shellfish supplies.[1] | Watch next: Watch for research clarifying Southern Hemisphere atmospheric effects and assessing the intervention alongside emissions reduction and carbon removal.[1]