A new study challenges geoengineering assumptions and suggests existing planes could inject cooling aerosols over the poles, opening the door to near-term deployment.

Existing aircraft could inject aerosols over polar regions

In response to fears of climate tipping points and slow emissions reductions, researchers are re-examining solar geoengineering strategies. A key method—stratospheric aerosol injection (SAI)—involves releasing sulphur dioxide into the upper atmosphere to reflect sunlight. While previous models required new aircraft to fly above 20 kilometers in tropical zones, new findings from University College London suggest commercial jets could perform similar injections over the poles at lower altitudes.

A commercial approach to stratospheric cooling

The UK Earth System Model was used to simulate 41 deployment scenarios. The team discovered that aircraft like the Boeing 777F could inject aerosols at 13 kilometers (about 8 miles) over 60° North and South and still achieve meaningful cooling—albeit with 35% lower efficiency than high-altitude methods.

“This has implications for how quickly stratospheric aerosol injection could be started and by who,” said lead author Alistair Duffey of UCL.

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Why polar regions matter for injection

The poles offer strategic benefits: the stratosphere lies closer to the surface, allowing standard commercial jets to reach it. Injecting 12 million tonnes of sulphur dioxide annually at 13 kilometers in these regions could lower global temperatures by 0.6°C—comparable to the cooling from the 1991 Mount Pinatubo eruption. However, these particles would only remain in the atmosphere for months, necessitating more frequent injections than at higher altitudes.

Timing injections for greater impact

Seasonal timing proved crucial. Injecting aerosols during local spring and summer maximized sunlight exposure, which aids chemical conversion to sulphuric acid and enhances aerosol longevity. This seasonal strategy boosted cooling effectiveness by 39% compared to year-round efforts, while also reducing some unintended warming effects from larger particles.

Speed advantage from using commercial jets

One of the main benefits of this approach is rapid deployability. While high-altitude aircraft may take a decade to develop, modified commercial jets could begin operations in just a few years. A fleet of 102 aircraft, each capable of carrying over 100 tonnes of material, could deliver enough sulphur dioxide for 1°C of global cooling annually—more efficiently than custom-built high-flying fleets.

“This route would be much quicker than designing a novel high-flying aircraft,” said Yale Lecturer Wake Smith.

Challenges: infrastructure, side effects, equity

Still, this approach comes with serious drawbacks. More sulphur dioxide is needed to achieve results, increasing risks of acid rain, ozone impacts, and health issues. Infrastructural gaps, especially in the Southern Hemisphere, limit practical deployment. Most notably, this strategy cools the poles more than the tropics—potentially exacerbating global inequality, as equatorial regions face the highest climate vulnerability.

Not a substitute for emissions reduction

Experts caution that even if low-altitude SAI becomes feasible, it cannot replace the need to drastically cut greenhouse gas emissions.

“We can only achieve long-term climate stability with net zero,” said co-author Dr. Matthew Henry from the University of Exeter.

SAI must be deployed gradually to avoid “termination shock”—a rapid warming rebound if injections suddenly stop—posing risks to agriculture, ecosystems, and human health.

A possible but imperfect tool

This study expands what’s technically possible in climate intervention. It introduces a lower-cost, near-term strategy using current technology, but it remains less effective and more controversial than higher-altitude methods.

Whether this commercial aircraft-based geoengineering becomes reality hinges on international decisions, ethical considerations, and continued research. But it undeniably adds a new dimension to the global climate conversation.

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