Holy sun-repellant spray, Batman! Could injecting billions of kilograms of sunlight-dimming aerosols into the atmosphere save the planet from industrial climate destruction? Or is that just Joker-level insanity? A new Columbia Climate School report definitely suggests that caution is warranted.<\/p>\n
Stratospheric aerosol injection (SAI) is essentially a \u201cnon-nuclear winter\u201d in which an intentionally deployed atmospheric shroud would block sunlight from heating the earth, allowing industrial pollution to continue as usual. But why would anyone consider such a risky, dramatic climate plan at all, especially one previously dismissed as science fictional? But what about all our recycling, car-pooling, biking, hiking, and gardening? Aren\u2019t we in the end-game of stopping an eco-killing Thanos from snapping his fingers and our snapping our biosphere\u2019s neck?<\/p>\n Not even close. Greenhouse gas emissions aren\u2019t slowing \u2013 they\u2019re actually increasing. As the International Energy Agency <\/a>reported in 2024, carbon emissions from the energy sector reached a new record as total \u201cenergy-related CO2\u202femissions increased by 0.8% … hitting an all-time high of 37.8 Gt CO2.\u201d<\/p>\n And according to the Royal Meteorological Society<\/a>, in 2024, for the first time, the world exceeded the 1.5 \u00b0C threshold for an entire year (in fact, it was 1.6 \u00b0C above pre-industrial levels). Keeping global temperate to no more than a 2 \u00b0C increase above pre-industrial levels, according to the Paris Agreement, stands between life as we know it and a cascading climate system failure that humans won\u2019t be able to stop.<\/p>\n Perhaps most unjust is the fact that populations who\u2019ve done the least to cause climate chaos face some of the greatest damage from it, as when rising sea levels swallowed eight Micronesian islands in 2017<\/a>, with Tuval, Kiribati, the Maldives and the Marshall Islands facing “stronger storms, freshwater shortages, and damaged infrastructure<\/a>” before potentially disappearing underwater.<\/p>\n So, in the face of unthinkable destruction, previously unthinkable proposals have now achieved thinkability. In 2018, we reported on a proposed 15-year SAI plan<\/a> to inject sulphates into the atmosphere about 20 km (12 mi) above ground, costing around US$2.25B annually.<\/p>\n Such a plan would require designing entirely new airplanes for payload delivery and require around 4,000 flights in its first year. Another SAI variation specifically targets the Earth\u2019s frigid polar regions<\/a>, refreezing them because they\u2019re warming more quickly than the rest of the planet and also causing sea levels to rise.<\/p>\n What are the risks of SAI?<\/p>\n But what if SAI doesn\u2019t work, and climate disruption keeps getting worse? Can we just take out whatever gases we put into the atmosphere? Well, no. SAI isn\u2019t the same as building a fence we can just tear down if we don\u2019t like. Removing gases and particles from the air is more like trying to take the chocolate out of a cake that\u2019s already baked because you want vanilla.<\/p>\n But what\u2019s far worse is that deploying SAI could be catastrophic, meaning we\u2019d be facing both climate chaos and whatever monsters we\u2019ve unleashed. That brings us to the new Columbia Climate School report by Miranda Hack, V. Faye McNeill, Dan Steigart and Gernot Wagner, published in Nature<\/a> in October 2025. <\/p>\n The scientists state, \u201cWithout international cooperation, SAI could do more harm than good.\u202fUnilateral or poorly planned deployment could worsen droughts, disrupt monsoons, or shift storm patterns.\u201d Just as the eruption of Mt. Pinatubo \u201cdisrupted the Indian monsoon system, leading to decreased rainfall across South Asia, and caused warming in the stratosphere and depletion of the ozone layer,\u201d SAI could cause \u201cacid rain and soil pollution.\u201d<\/p>\n That\u2019s because when high-altitude clouds of sulfur dioxide eventually form sulfuric acid, the resulting acid rain will help destroy the forests, jungles, crops, tigers, penguins, and reindeer that SAI was supposed to protect.<\/p>\n The authors of the report also caution policy makers that most \u201cSAI modeling literature focuses on optimal deployment scenarios, in which practical constraints \u2013 microphysical, geopolitical, and economic \u2013 are not considered.\u201d<\/p>\n In other words, SAI assumes that all governments and corporations will cooperate nicely, which can happen, as with the 1987 Montreal Protocol <\/a>and its amendments to save the ozone layer by phasing out chlorofluorocarbons. But as Earth.org <\/a>chillingly and succinctly reports, \u201cenvironmental treaties consistently fail.\u201d<\/p>\n
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Because, as a previous report <\/a>by the Inter-Governmental Panel on Climate Change states, industrial climate change is causing wide, \u201crapid changes in the atmosphere, ocean, cryosphere [ice zones], and biosphere\u201d that are altering \u201cweather and climate extremes in every region across the globe.\u201d The result is \u201cadverse impacts and related losses and damages to nature and people.\u201d<\/p>\n