Reducing carbon dioxide emissions is a long and arduous process, but researchers are looking at another potential way to address Earth’s climate crisis: putting reflective particles into the atmosphere. On June 15, 1991, Mt. Pinatubo erupted in the Philippines, releasing almost twenty million tonnes of sulfur dioxide. In the next 18 months, a layer of ash covered the sky, and the average temperature of the entire world decreased by around 0.5˚C, only rising again once the particles had left the atmosphere. While its eruption devastated much of the Philippines, many scientists saw the benefits that could result in another explosion like this one.
A handful of Harvard researchers founded the Stratospheric Controlled Perturbation Experiment (SCoPEx) to explore the possibilities of injecting particles into the atmosphere to reflect the sun’s rays and cool Earth’s temperature. The idea is similar to the one employed by the Arctic Project (see Change the End’s previous article). Scientists hope to minimize the potential damage that particles could have on the ozone layer and maximize their ability to reflect sunlight. SCoPEx researchers opted to use calcium carbonate instead of sulfur dioxide, the particle that was released from the Mt. Pinatubo eruption. Although sulfur dioxide did indeed cool the planet, they also sped up the rate at which other particles depleted the ozone layer. SCoPEx scientists state that calcium carbonate, unlike sulfur dioxide, would have a smaller impact on the ozone layer. Additionally, this particle could potentially react with ozone-destroying molecules and help replenish the ozone layer.
SCoPEx plans on using a steerable balloon to carry and release the calcium carbonate particles into the stratosphere. They hope to do their first dry run in June 2021 to ensure that their machine works. Subsequently, they will set a date for an official experimental test run based on how well their balloon worked. Approximately two kilograms of calcium carbonate will be released in the experimental run. If everything goes according to plan, SCoPEx will be the first lab in the world to move solar geoengineering out of the lab. Their first phase (involving those two test runs) costs around three million USD, the predicted annual cost coming down to between one and ten million USD.
However, the truth is that we cannot mimic the atmosphere in a lab. Calcium carbonate does not naturally exist in our atmosphere and the research done by scientists only scratches the surface of how the molecules could react with the stratosphere. Some scientists are skeptical about the side effects to this solution. If we miscalculate and send too many particles into the ozone layer, too much light will be reflected and crops will fail; subsequently, animals, including humans, will die. Additionally, blocking too much sun can change weather and ocean current patterns. Some skeptics speculate that we may be “locked in for life.” These calcium carbonate particles only stay in the ozone layer for around two years. Once they leave, Earth’s environment would have little time to readjust to the hot rays after adapting to having less sun, resulting in catastrophic consequences. Despite these concerns, research around this topic has been promising. In 2011, scientists conducted the Eastern Pacific Emitted Aerosol Cloud Experiment where they pumped smoke into the lower atmosphere to mimic pollution from ships. The clouds produced a cooling effect fifty times greater than the warming effect from their ship.
If these particles cool our planet, we have the option of continuing fossil fuels emissions at the price of sending out more and more particles to repair the ozone layer and repel the sun’s rays. As appealing as this plan may sound, not addressing the root problem of carbon dioxide emissions will ultimately harm us; the amount of particles we can emit is finite. Scientists predict that the best way to clean up mother earth is to eliminate fossil fuels entirely and remove the remaining carbon dioxide: Carbon Capture and Sequestration (CCS). Simply reducing carbon emissions is not as effective as you may think. Carbon dioxide stays in the atmosphere for thousands of years; the repair of the ozone layer would be an excruciatingly slow process. However, carbon capture, an expensive but effective means of repairing our climate, is a feasible solution to this massive problem. CCS removes carbon dioxide from the air and traps it in minerals that can be stored in Earth’s crust. Check in next week to read an article with a more detailed explanation of CCS.
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www.sciencemag.org/news/2020/12/geoengineers-inch-closer-sun-dimming-balloon-test Accessed 2 Feb. 2021.
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