Geoengineering solves warming, inequality, cyclones—experts agree

[TARA YARLAGADDA, 4-7-2021, "1 big pro and 4 cons of solar geoengineering," ] WL

Combating the climate crisis seems simple: We have to reduce global greenhouse emissions and keep temperatures from climbing more than 1.5 degrees Celsius above pre-industrial levels. Achieving this goal, however, has proved difficult. That’s why some experts are advocating more extreme, technology-driven measures like solar radiation modification (SRM). However, as scientists argue in a paper released Monday in the Proceedings of the Natural Academy of Sciences, actually implementing SRM could trigger various “impacts and risks.” What is geoengineering? Forest fire and smoke in Australia A forest fire near the Blue Mountains in Australia. Climate change has exacerbated this fires, but some scientists think solar geoengineering could help solve this problem. Getty Geoengineering broadly refers to the concept of using technology to alter climate on a large scale using emerging technologies. According to the study, there are two main types of geoengineering: Carbon dioxide removal Solar radiation modification Carbon dioxide removal, also known as carbon geoengineering or carbon capture, uses machines to suck greenhouse gases out of the air and counteract the effects of global warming. The technology has been around since the 1970s, but it only became popular in recent years. Carbon capture has become widely accepted by climate scientists and policymakers — including President Joe Biden — though some argue that it remains prohibitively expensive. Despite the cost, the effects of carbon dioxide removal are relatively straightforward and easy to explain. That’s not exactly the case for solar radiation modification. How does solar geoengineering work? Solar radiation modification, more commonly known as solar geoengineering, involves reflecting the sun’s rays away from the Earth’s surface. The goal is to increase surface albedo, the fraction of sunlight reflected by the surface of the Earth. “Surface albedo is the same as the reflectivity, shininess of the Earth's surface as seen from space,” climate strategist Jørgen Randers previously told Inverse. “Bright surfaces like snow and ice reflect most of the incoming energy from the Sun.” The idea is that, by increasing the albedo or reflectivity of Earth’s surface, scientists can use solar geoengineering to deflect a certain amount of sunlight and stabilize the planet’s surface temperature. Within the larger category of solar geoengineering are different schemes, like stratospheric aerosol scattering — also known as stratospheric aerosol intervention (SAI). What are the different types of solar geoengineering? An illustration of one type of solar geoengineering stratospheric aerosol intervention (SAI), from a March 2021 study in Proceedings of the National Academy of Sciences Solar geoengineering can take many forms, including: Marine cloud brightening involves dousing clouds with seawater to increase their brightness, ultimately helping the clouds reflect sunlight back into space and away from Earth. Cirrus cloud thinning entails injecting ice crystals into certain high altitude “cirrus” clouds, which trap heat and warm the planet. The ice crystals allow for heat to escape from the clouds. Space-based techniques involve not only researching the effects of sunlight on Earth’s ozone layer but also installing giant sun shields to reflect sunlight away from Earth. This latest PNAS study discusses the final technique: stratospheric aerosol intervention (SAI). This hypothetical technique introduces reflective material, such as sulfate aerosols, into the stratosphere — the Earth’s upper atmosphere. These aerosol particles would then reflect sunlight away from Earth and back into space. SAI works in a similar way to volcanoes, which cool the Earth by releasing gaseous aerosols into the stratosphere after an eruption. Some scientists suggest that a “cocktail” or mixture of these various geoengineering approaches is the best way to combat the climate crisis. The benefits of solar geoengineering The scientists in the PNAS study describe SAI — a type of solar geoengineering — as a “scheme that is likely to have a large impact on Earth’s surface temperature.” Ultimately they agree it could induce one major benefit: lowering Earth’s global temperature. That’s essentially the point of solar geoengineering — reducing temperatures and offsetting the costs of global warming. A 2019 Nature study suggests the right “dose” of solar geoengineering could cut massively cut the planet-warming induced carbon dioxide emissions. “Previous work had assumed that solar geoengineering would inevitably lead to winners and losers... our work challenges this assumption,” the Nature team argued in a statement. By reducing global temperatures, solar geoengineering could mitigate the impacts of natural disasters. The same Nature study finds that solar geoengineering could offset the increased risk of tropical cyclones from carbon dioxide emissions. Cooling temperatures could even help reduce income inequality, according to a 2020 study published in Nature Communications.