Scientists Model Sulfur Aerosols to Cool Oceans as Air Conditioning Demand Set to Triple Worldwide

Western Europe just logged its hottest June on record in 2026, and ocean surface temperatures outside the poles hit their highest point since record-keeping began, according to reporting from The Times of India. Scientists say that combination is consistent with broader climate data showing the planet is warming to levels unseen in roughly 6,500 years.

One group of researchers thinks it may have found a way to blunt the damage. A team led by Dr. Lala Kounta at Michigan State University used a peer-reviewed climate simulator called ARISE-SAI to test what happens if reflective aerosols are deliberately injected into the upper atmosphere. Their findings, published in a journal from IOP Science, suggest that limiting warming to 2.5°F would require injecting up to 11 million tons of sulfur dioxide into the atmosphere every year. The model showed that dose could cut ocean heat-wave intensity by 25% and shorten heat-wave duration by 21%.

This is a computer simulation, not a field-tested program. Nobody has sprayed 11 million tons of sulfur dioxide into the sky and watched what happens to rainfall patterns, ozone, or agriculture in places that didn't sign up for the experiment. Solar geoengineering research has drawn criticism for exactly that reason: it treats a planetary-scale intervention as reversible and controllable when in reality nobody fully knows the consequences. The Times of India's framing, borrowed partly from a BGR report, calls this a potential 'cooling solution' without dwelling on the fact that it's one model's projection, not an engineering plan with a price tag or a governing body attached.

The stakes for doing nothing are real. Marine heat waves have already been linked to sharp die-offs in Alaskan snow crab populations, more frequent coral bleaching events, and the spread of toxic algae that can poison shellfish supplies, according to the same reporting.

The cheaper, messier fix is already running full blast

While scientists model sulfur injections, most of the world is reaching for a much older technology: the air conditioner. A study published Monday in Nature Health, led by Yale School of Public Health epidemiology professor Kai Chen, found that air conditioning saved nearly 58,000 lives in the United States between 2010 and 2020, and saves more than 5,000 Americans a year now. United Nations officials estimate roughly 500,000 people die from heat globally each year.

Chen didn't sugarcoat the trade-off. 'Everyone knows air conditioning works, but air conditioning from a climate change perspective is not an ideal,' he said, according to KIRO 7. 'It leads to more carbon emissions ... then it accelerates the climate warming problem.'

The numbers back him up. The International Energy Agency and the United Nations Environment Programme project cooling-related electricity demand will triple worldwide, and the UN projects annual carbon emissions from air conditioning will rise from 4.5 billion tons to 7.2 billion tons over the next 25 years, nearly matching current combined output from the United States and Europe.

Cooling degree days, a measure of how much energy buildings need for cooling, are up 28% in the U.S. since 1990, with 2024 setting a record. Through May, 2026 was on pace to beat that record, according to the U.S. Energy Information Administration. In Europe, cooling degree days have more than doubled since 1990 and AC use is up 44%. India has tripled its AC use, and Southeast Asia has more than doubled it, per IEA data.

Some governments are already rationing cooling

An energy crunch tied to the Iran war has pushed eight countries, Bangladesh, Cambodia, Jordan, Malaysia, the Philippines, the Seychelles, Singapore, and Sri Lanka, to cap how cold offices can be set or to mandate weekly shutoffs of AC in public buildings, according to the IEA. India proposed similar temperature limits on air conditioners in 2025.

The reasoning behind those caps is straightforward: if the grid can't handle the load and most of that power comes from burning fossil fuels, unrestricted cooling accelerates the exact warming making the heat worse. That's the reasoning behind why 75 countries and 250 cities are sending delegates to the Global Cooling Pledge meeting scheduled for this month in Singapore.

But rationing the one proven tool that reliably keeps people from dying in extreme heat, especially in poorer, hotter countries with less reliable power grids to begin with, carries its own body count. Chen's study shows air conditioning already prevents thousands of U.S. deaths a year; scaling that math to the roughly half a million global heat deaths the UN counts annually suggests the stakes of getting cooling policy wrong cut both ways.

Neither the geoengineering research nor the AC rationing has moved past the modeling and pilot stage. No country has approved a stratospheric aerosol program, and the caps on AC use so far are limited to the eight nations named by the IEA. What happens at the Global Cooling Pledge meeting in Singapore this month, and whether Kounta's team seeks funding for real-world testing, are the next concrete markers to watch.