Potential last-ditch efforts to avert the worst impacts of global warming by geoengineering Earth's climate could themselves be harmful, a new study suggests.
Why it matters: With global concentrations of greenhouse gases continuing on an upward trajectory — and no sign of the end of fossil fuel use — some researchers are turning to technological fixes like geoengineering the climate. But the new study underscores the potential unintended and unknown consequences of the technology.
“In some ways this study is a note of caution that with a planetary scale technology like this there may be a lot of outcomes that surprise us. There is so much more that we don’t know than we do know.”— Jonathan Proctor, University of California at Berkeley
Background: Right now, the world is on course to experience a greater amount of global warming than the 2°C, or 3.6°F, target under the Paris Climate Agreement.
Scientists are studying whether the planet can be veiled in particles that would reflect incoming sunlight and offset warming of the planet.
- These solar radiation management (SRM) schemes are a type of geoengineering that would involve wrapping Earth in a "stratospheric veil."
- Groups at Harvard and other universities are focusing on taking geoengineering from the theoretical to the technically deployable stage during the next several years.
What's new: A study published in Nature this week finds reason to be cautious about assuming that SRM would benefit crops by protecting plants from heat-related impacts and making sunlight more diffuse.
The researchers used computer modeling that incorporates two large past volcanic eruptions — El Chichón in 1982 and Mount Pinatubo in 1991 — as an analog to SRM plans.
Powerful volcanic eruptions can loft the chemical precursors to sulfate aerosols into the stratosphere. Mount Pinatubo, for example, sent 20 million tons of sulfur dioxide into the upper atmosphere, where it then formed aerosols.
What they found: The damages seen during the mid-20th century from the way that sulfate aerosols scatter sunlight are about equal to the projected benefits to crops from cooling the planet. The net effect, then, would "attenuate little of the global agricultural damage from climate change," the study says.
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