A "Chemistry of Natural Resources" paper from the U.K. presents "Criegee biradicals" as the new go-to for shading the earth from the sun (read the paper here). Stating: "Free radical chemistry is very important in the Earth's atmosphere. It regulates ozone levels ... and drive[s] photochemical smog formation," the paper explains that non-soot aerosol particles cool the planet by acting "like little mirrors and reflect[ing] visible light from the sun back into space."
We are also told that Criegee biradicals can be found, as a result of atmospheric chemistry, "inside or downwind of urban areas, as well as over forests. Downwind of urban areas, particularly on sunny days, high concentrations of ozone form part of photochemical smog. Vehicle emissions will release alkenes [volatile organic compounds] into the atmosphere as well. In these polluted plumes, it is perfectly possible to generate high ozone and high alkene concentrations, leading to elevated concentrations of Criegee biradicals."
The summary is that these things called Criegee biradicals are the reason for what you and I call chemtrails: they make hygroscopic (water-loving) compounds that draw atmospheric moisture, resulting in a protective, reflective "photochemical smog" that may be the answer to our current extremes of temperature. Additionally, students taking A-Level exams (age 18) are instructed to read this paper and be prepared to answer test questions on Criegee biradicals. Might this be chemtrail propaganda for budding minds ...?