Researchers Propose Stratospheric Aerosol Injection to Reduce Ocean Heat Waves

A prolonged heat wave swept across Western Europe in the summer of 2026, pushing the region to its hottest June on record. The event has been presented as proof of wider climate studies indicating Earth is warming to levels unseen in roughly 6,500 years. The world’s oceans saw their highest average sea-surface temperature outside the polar regions since records began the following month, raising concerns that marine heatwaves are worsening. In response, a team of researchers led by Dr Lala Kounta at Michigan State University has proposed a potential cooling method involving reflective aerosols released into the Earth's upper atmosphere. ​According to a report by BGR, the consequences extend well beyond warmer water. Marine heat waves have been linked to sharp declines in species such as Alaskan snow crabs. Coral reef systems, already close to a tipping point in many regions, face bleaching events that can prove fatal to the reef. Rising ocean temperatures have also been associated with the spread of toxic algae, which can poison marine life and contaminate shellfish supplies.

​Ocean heat wave research points to a possible cooling solution

​In a paper published in IOP Science, Dr Lala Kounta and researchers from several institutions used the peer-reviewed ARISE-SAI climate intervention simulator to examine how aerosol-based cooling may affect heat waves across global oceans. ​The team's modelling found that limiting global warming to 2.5 degrees Fahrenheit would require injecting up to 11 million tons of sulfur dioxide annually, which the simulation showed could reduce ocean heat-wave intensity by 25% and shorten duration by 21%. ​A more ambitious target of 2 degrees would require up to 22 million tons of sulfur dioxide per year, with modelled reductions of 75% in intensity and 80% in duration. According to the simulations, most of the aerosol would settle in the Southern Hemisphere, where broader atmospheric effects remain unclear. The tropical Atlantic, Indian Ocean, Arctic Ocean, and South Atlantic showed the largest modelled benefits.

​How stratospheric aerosol injection would work

​The technique, known as stratospheric aerosol injection (SAI), has not been deployed at scale to cool the planet, though the underlying chemistry has precedent. Volcanic eruptions release sulfur dioxide that converts into light-reflecting aerosols once airborne. ​Researchers point to the 1991 eruption of Mount Pinatubo in the Philippines, which released an estimated 22 million tons of sulfur dioxide and was followed by a global average temperature drop of more than 1 degree Fahrenheit lasting nearly two years. ​Replicating that effect would involve flying specialised aircraft into the stratosphere to release sulfur dioxide, which would react with water vapour and other atmospheric compounds to form aerosol droplets. ​Placement in the stratosphere is considered necessary because aerosols released at lower altitudes would be removed by rainfall. The ARISE-SAI simulator allowed Kounta's team to test injection at multiple latitudes and measure the resulting changes in heat-wave intensity and duration.

​Aerosol cooling would not resolve ocean acidification

​Researchers noted that cooling oceans through aerosol injection would not address the broader effects of climate change. Oceans would continue absorbing atmospheric carbon dioxide under this scenario, a process that alters seawater chemistry and drives acidification independent of temperature. ​For that reason, the study's authors said emissions reductions and targeted carbon dioxide removal remain necessary alongside any intervention involving aerosols. The findings, they said, indicate that stratospheric aerosol injection could serve as one component among several approaches to managing ocean warming. ​

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