A sun reflector for Earth? Scientists explore possible risks and benefits


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Nine of the hottest years in human history have occurred in the last decade. Without a major change in this climate trajectory, the future of life on Earth is in doubt. Should humans, whose fossil fuel society drives climate change, use technology to slow global warming?

Every month since September 2019, the Climate Intervention Biology Task Force, a team of internationally recognized experts in climate science and ecology, has met remotely to bring science closer to that question and the consequences of geoengineering a colder Earth by reflecting a portion of the solar energy. Radiation away from the planet: a climate intervention strategy known as solar radiation modification (SRM).

The group’s landmark article, “Potential Ecological Impacts of Climate Intervention Reflecting Sunlight to Cool the Earth,” was published in the most recent procedures of the National Academy of Sciences (PNAS).

“Participation in this working group has been very revealing to me,” said co-author Peter Groffman, an ecosystem ecologist at the Center for Advanced Scientific Research at the Graduate Center, CUNY and the Cary Institute for Ecosystem Studies. “I did not know that climate intervention modeling was so advanced, and I think that climate modelers were not aware of the complexities of affected ecological systems. It is a strong reminder of the importance of the need for multidisciplinary analysis of complex problems. in environmental science. “

The interdisciplinary team is co-chaired by Phoebe Zarnetske, Community Ecologist and Associate Professor in the Department of Integrative Biology and the Ecology, Evolution and Behavior program at Michigan State University, and ecologist Jessica Gurevitch, Distinguished Professor in the Department of Ecology and Evolution of Stony. Brook University.

Conversations between Gurevitch and climate scientist Alan Robock, Distinguished Professor in the Department of Environmental Sciences at Rutgers University, resulted in the pioneering group, which is more aware than most that geoengineering Earth’s atmosphere is more than a simple sci-fi setting.

“There is a dearth of knowledge about the effects of climate intervention on ecology,” Zarnetske said. “As scientists, we must understand and predict the positive and negative effects it could have on the natural world, identify key knowledge gaps, and begin to predict what impacts it could have on terrestrial, marine and freshwater species and ecosystems if adopted. in the future “.

The costs and technology required to reflect the Sun’s heat back into space are currently more achievable than other climate intervention ideas such as absorbing carbon dioxide (COtwo) from the air. The working group anticipates that its lively discussions and open access document will fuel an explosion of scientific research on how a climate intervention strategy known as solar radiation modification (SRM), along with reducing greenhouse gas emissions greenhouse, it would affect the natural world.

The feasibility of SRM’s efforts around the planet depends on accurate predictions from its myriad results provided by the well-established computer simulations of the Geoengineering Model Intercomparison Project (GeoMIP). The PNAS The document lays the foundation for expanding the scope of GeoMIP to include the incredible variety and diversity of Earth’s ecosystems.

“While climate models have become quite advanced in predicting the climate outcomes of various geoengineering scenarios, we have very little understanding of what the potential risks of these scenarios could be to species and natural systems,” Gurevitch explained. “Are the risks of extinction, species community change, and the need for organisms to migrate to survive under SRM greater than those of climate change, or does SRM reduce the risks caused by climate change?”

“Most GeoMIP models only simulate abiotic variables, but what about all living things that are affected by climate and depend on energy from the sun?” Zarnetske added. “We need to better understand the potential impacts of SRM on everything from soil microorganisms to monarch migrations and marine systems.”

The Zarnetske Space and Community Ecology Laboratory (SpaCE Lab) specializes in predicting how ecological communities respond to climate change on scales from the microcosm to the global, making it uniquely prepared to help the task force illuminate vital data. for future SRM scenarios such as Stratospheric Aerosol Intervention (EFS), the central topic of the article.

SAI would reduce some of the incoming radiation from the Sun by reflecting sunlight back into space, similar to what happens after large volcanic eruptions. Theoretically, it would be possible to continually replenish the cloud and control its thickness and location to achieve the desired target temperature.

But the paper reveals the little-researched complexity of the cascading relationships between ecosystem function and climate in different SAI scenarios. In fact, they argue, climate change mitigation must continue regardless of whether SRM is adopted, and the question remains whether any SRMs can be beneficial in addition to decarbonization efforts.

“Although SAI can cool the Earth’s surface to a global temperature target, the cooling can be unevenly distributed, affecting many ecosystem and biodiversity functions,” Zarnetske said. “Rain and UV radiation from the surface would change, and the SAI would increase acid rain and not mitigate ocean acidification.”

In other words, SRM is not a magic bullet for solving climate change. Until the task force’s efforts inspire new research on the effects of different climate intervention scenarios, SRM is more like a shot in the dark.

“We hope that this paper will bring more attention to this topic and greater cooperation between scientists in the fields of climate science and ecology,” added Gurevitch.

The Climate Intervention Biology working group is funded by the National Science Foundation and will host sessions at two upcoming scientific conferences: “Biosphere Responses to Geoengineering” at the American Association for the Advancement of Science (AAAS) annual meeting ) this month, and in The Ecological Society of America in August 2021.


Geoengineering is only a partial solution to combat climate change


More information:
Phoebe L. Zarnetske el al., “Possible Ecological Impacts of Climate Intervention Reflecting Sunlight to Cool the Earth”, PNAS (2021). www.pnas.org/cgi/doi/10.1073/pnas.1921854118

Provided by Graduate Center, CUNY

Citation: A sun reflector for Earth? Scientists Explore Potential Risks and Benefits (2021, April 5) Retrieved April 6, 2021 from https://phys.org/news/2021-04-sun-reflector-earth-scientists-explore.html

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