Geoengineering is too risky and slow to be an effective solution to warming

Geoengineering Is Not a Quick Fix for the Climate Crisis, New Analysis Shows The IPCC recently warned about missing global temperature goals, raising interest in technologies such as solar geoengineering. Credit: Pierre Longnus/Getty Images CLIMATEWIRE | A controversial idea for cooling the earth’s climate through artificial means would likely require a much longer global commitment than policymakers and the public understand, according to a recent study that raises new questions about the potential for using solar geoengineering. If world leaders decide to use solar geoengineering to meet international climate goals, they could be locked into it for a century or more, the study suggests. The potentially long timeframe further complicates the debate about geoengineering and its viability. Geoengineering is “often communicated as temporary, a stopgap measure — so it implies being relatively short, and short in the sense of a couple of decades,” said lead study author Susanne Baur, a doctoral candidate at the European Centre for Research and Advanced Training in Scientific Computation in France. “And so when we started looking at these pathways, and we extrapolated them a bit longer, we saw that in many cases, it’s actually not that short.” The public may not realize the scope of a commitment solar geoengineering — or its risks, including the need for long-term international cooperation. “If we have to keep up a system like this for such a long time, that just increases the possibility of something bad happening,” Baur said. Solar geoengineering refers to a kind of climate geoengineering aimed at manipulating the amount of solar radiation that hits the planet. The most commonly discussed strategy involves spraying special reflective aerosols into the atmosphere to beam sunlight away from the earth, lowering global temperatures. It’s just an idea for now. And it’s highly contentious. Solar geoengineering risks and side effects range from possible damage to the earth’s ozone layer to inadvertent changes in global precipitation patterns. Once started, it would be dangerous to stop unless enough carbon had been sucked out of the atmosphere to lower the earth’s temperatures below a safe threshold. Otherwise, a sudden halt to geoengineering could cause temperatures to skyrocket, potentially faster than life could adapt, a concept known as “termination shock.” The risks have prompted scientists to urge international discussion and agreement about regulating geoengineering experiments and deployments. The new study, published March 28 in the journal Earth System Dynamics, analyzes how solar geoengineering could be used to meet climate targets and how long the world would have to maintain the practice to meet the targets. The time frames range vastly, the study finds. If nations quickly reduce emissions and atmospheric carbon, solar geoengineering could be unnecessary. But based on the carbon-cutting commitments nations have made under the 2015 Paris Agreement, solar geoengineering would likely have to persist for at least a century to keep global warming within a threshold of 1.5 degrees Celsius, the study found. The study modeled hundreds of potential geoengineering scenarios to account for factors such as how quickly global emissions fall, how much carbon is removed from the atmosphere each year and how the climate system physically responds, which is still uncertain. Although the projected timelines range from no geoengineering to hundreds of years, few scenarios resulted in a timeline of less than 100 years. Those scenarios generally assume extremely aggressive climate action.