As the debate over solar geoengineering heats up, a growing number of scientists are moving beyond computer models to tackle the practical challenges of deliberately intervening in the climate. Jim Franke, a research assistant professor at the University of Chicago, has on his desk plans for an uncrewed aircraft with enormous wings designed to fly over 20 kilometers high, into the stratosphere. There, mimicking the cooling effect of volcanic eruptions, particles could be released to reflect sunlight and lower global temperatures.
The concept of solar geoengineering is not new, but current research marks a turning point. According to Franke, "if you want to get to 20 kilometers in the near term, this is probably the best bet." However, the necessary aircraft do not yet exist, and many unknowns remain: which material to release, how to prevent particles from clumping and falling, and what the side effects might be. To address these, the Climate Systems Engineering Initiative (CSEi) at the University of Chicago, led by David Keith, is coordinating concrete engineering projects.
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From Models to Practice: Technical Challenges
One critical issue is the lack of suitable aircraft. Commercial jets fly too low; stratospheric planes with oversized wings are needed to carry payloads in thin air. Moreover, the chemistry of particles is complex: sulfur dioxide, once released, transforms into reflective aerosols, but the process is influenced by countless variables. Research is also exploring alternatives like hydrogen sulfide. According to an analysis by the nonprofit Reflective, a "well-managed, moderate" scenario foresees starting in 2035 with launches near the poles, where the stratosphere is lower, initially cooling the planet by 0.1 °C, up to 0.5 °C by 2045. However, this would lead to uneven effects, with less cooling in the tropics, already vulnerable to warming.
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Critics, such as Jennie Stephens of Maynooth University, warn that every investment in research makes actual deployment more likely, with unpredictable risks for complex planetary systems. Proponents argue that only by studying the details of how to implement geoengineering can we assess benefits and dangers, avoiding reckless interventions. Europe watches this debate with apprehension, as other nations may act unilaterally.
The road is still long: investments in monitoring infrastructure, new materials, and international collaborations are needed. As Franke says, "we're not interested in turning the crank on more models; we want to see how you'd actually do this thing." Meanwhile, research advances amid innovation and controversy. For more context on green technologies, see the ongoing green revolution.
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Solar geoengineering remains one of the most controversial and fascinating ideas to combat climate change. As the world struggles to reduce emissions, understanding whether and how we could "hack" the atmosphere is a question deserving science and engineering-based answers. Learn more about solar geoengineering on Wikipedia.
Source: https://www.technologyreview.com/2026/06/17/1138743/hacking-atmosphere-geoengineering-reality-check
