U.S. needs solar geoengineering research program, report says

doi:10.1126/science.372.6537.19

GSTDTAP > 气候变化

DOI	10.1126/science.372.6537.19
	U.S. needs solar geoengineering research program, report says
	Paul Voosen
	2021-04-02
发表期刊	Science
出版年	2021
英文摘要	An influential panel of scientists has recommended the United States pursue a robust research program into a controversial technological bandage for climate change. Solar geoengineering—deliberately altering the atmosphere to reflect more sunlight—might forestall some of the worst effects of global warming, but fears of tinkering with climate systems and the technology's potential for misuse have slowed research. Unabated global warming is changing the calculus, however, and a new report from the National Academies of Sciences, Engineering, and Medicine (NASEM) urges the government to fund a cautious but expansive effort that could total $200 million over 5 years. The panel's recommendation is “thrilling,” says David Keith, a Harvard University energy and climate scientist and longtime proponent of geoengineering research. The report sets multiple conditions: Any experiments would require substantial oversight, risk assessment, and public outreach. Field tests should only move forward if they provide observations that could not be made in the lab or by observing sunlight-altering natural events, such as volcanic eruptions. And, says Chris Field, a climate scientist at Stanford University and chair of the committee, “Learning more about these technologies shouldn't be seen as a step toward deployment.” The 25 March report also makes clear that no research should occur without strong government commitments to reducing emissions. Reflecting sunlight without curbing carbon dioxide emissions would do nothing to slow the acidification of the oceans, for example. Solar geoengineering “only makes sense in the context of a primary societal and government focus on mitigation and adaptation,” says Peter Frumhoff, chief climate scientist at the Union of Concerned Scientists and co-author of the report. “It makes no sense otherwise.” In preparation since 2019, the report takes a close look at three proposed solar geoengineering strategies: stratospheric aerosol injection, which would release long-lived reflective particles into the upper atmosphere; marine cloud brightening, which seeks to thicken low-lying clouds over the ocean; and cirrus cloud thinning, which would alter wispy high-altitude ice clouds, allowing more infrared radiation to escape to space. Each has its own risks and uncertainties: Particles released into the stratosphere, home of the ozone layer, could have long-lasting, global effects. Cloud thickening and thinning, though taking place on more regional scales, would change cloud properties with unpredictable results. The report recommends that the U.S. Global Change Research Program, which coordinates federal climate research from the White House, lead the effort and establish a standing advisory body that would include scientists, policymakers, and representatives from civil society. Any research agenda should include studying the interplay between solar geoengineering and public perceptions, politics, and socioeconomic trends, along with its ethical dimensions, the panel wrote. And experiments should be designed to explore risks as well as feasibility, Frumhoff says. “They should potentially have outcomes that could say, ‘This is not a good idea.’” That aligns with “how we hope to see this research evolve in the future,” says Sarah Doherty, an atmospheric scientist at the University of Washington, Seattle. Doherty is program director of the Marine Cloud Brightening Project, which plans within 1 year to test a nozzle that will spray sea salt particles to thicken ocean clouds, making them more reflective. The $200 million budget suggested by NASEM would be enough to support several aircraft campaigns, which might include the deliberate release of particles into the atmosphere. But the panel says any such releases should be minute, 100 times smaller than the smallest amount that could theoretically influence the environment or global temperature. Current U.S. research into solar geoengineering is fractured and ad hoc. The last two federal spending bills provided $13 million to the National Oceanic and Atmospheric Administration to pursue such studies—the first such funding. The agency is planning to fly a lunch box–size spectrometer into the stratosphere by balloon to capture a high-resolution view of long-lived, light-reflecting natural particles, with the first flight scheduled later this year. The rest of the money has, so far, gone to improving instrumentation, modeling the stratosphere, and studying how fine particles influence marine clouds, a long-standing research question. Without a strong U.S. government role, philanthropy has filled the void. Bill Gates has supported a project co-led by Keith: the Stratospheric Controlled Perturbation Experiment, which aims to release 2 kilograms of light-reflecting chalk in the upper atmosphere and observe the resulting plume. A proposal to test its experimental balloon rig above Sweden this year, without releasing particles, is pending before an independent review board, after a delay following an outcry from Swedish environmental groups. Meanwhile, last year SilverLining, a nongovernmental organization dedicated to supporting solar geoengineering research, announced $3 million in support to five research labs, largely focused on modeling. As pleased as Keith is with the NASEM report, he notes that other bodies have issued similar, though less ambitious, suggestions stretching back to the early 1990s. “The big question,” Keith says, “is will it happen?”
领域	气候变化 ; 资源环境
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文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/321115
专题	气候变化资源环境科学
推荐引用方式 GB/T 7714	Paul Voosen. U.S. needs solar geoengineering research program, report says[J]. Science,2021.
APA	Paul Voosen.(2021).U.S. needs solar geoengineering research program, report says.Science.
MLA	Paul Voosen."U.S. needs solar geoengineering research program, report says".Science (2021).