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To cool Earth, scientists just need a Boeing 777F and 12 million tons of sulfur dioxide every year. A study led by University College London suggests that stratospheric aerosol injection, a controversial geoengineering technique, could be done using existing planes like the Boeing 777F. The concept involves releasing tiny reflective particles into the stratosphere to reflect sunlight and reduce global temperatures. Until now, researchers believed this could only work from very high altitudes near the equator, requiring specially designed jets capable of flying at 12.4 miles (20 kilometers). But this study shows that injections from 8.1 miles (13 kilometers) above the polar regions – an altitude commercial jets already reach – could still have a measurable cooling effect. There’s a major tradeoff. Because particles at lower altitudes don’t stay suspended as long, this strategy would require three times as much material – around 12 million tons of sulfur dioxide annually. That raises concerns about more severe side effects, such as acid rain, and reduced effectiveness in the tropics, where warming is most intense. Still, researchers estimate it could cool the planet by around 0.6 degrees Celsius, similar to the global temperature drop caused by the 1991 Mount Pinatubo eruption. And unlike designing a new high-altitude aircraft fleet, which could take over a decade and cost billions, this method could be deployed much sooner. The study’s authors stress that this is not a solution to climate change and should not replace emissions reductions. But as climate risks grow, understanding every option matters – especially ones that could be implemented quickly. Learn more: "Geoengineering technique could cool planet using existing aircraft." UCL News, 28 April 2025.