To steer upcoming research on solar geoengineering, an international team of scientists is providing clear guidelines for assessing proposals to pinpoint the most viable and credible methods for stratospheric aerosol intervention.
For several years, researchers have examined the potential effectiveness of releasing sulfur dioxide into the stratosphere as a way to reflect sunlight and combat global warming. They are now emphasizing the importance of evaluating these solar geoengineering methods for their technical practicality, cooling effectiveness, and potential ecological and societal impacts.
An international team spearheaded by the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR) has unveiled a paper outlining specific recommendations for assessing sulfur dioxide injection proposals, which is also referred to as stratospheric aerosol intervention (SAI). Additionally, the paper proposes criteria for discontinuing scenarios deemed unworkable due to scientific, technical, or societal hurdles.
“Our aim is to establish an evaluation framework that can help identify the most practical and credible scenarios, based not only on their potential to reduce both natural and societal risks but also on any negative consequences they might generate,” stated NSF NCAR scientist Simone Tilmes, the paper’s lead author. “If society ever considers the implementation of SAI, it is crucial that we equip policymakers and the public with the most reliable scientific insights available.”
This study, which received funding from NSF and NOAA, has been published in Oxford Open Climate Change.
Imitating volcanic eruptions
Once sulfur dioxide is injected into the stratosphere, it transforms into sulfate aerosols that reflect sunlight. Past research, which utilized computer models and analyzed major volcanic eruptions, has indicated that these aerosols can produce a cooling effect akin to that of a significant volcanic event.
Such injections could potentially cool the planet for several decades or even centuries, providing a temporary solution until greenhouse gas levels in the atmosphere decrease.
However, earlier studies have also highlighted the potential dangers of SAI, including impacts on the stratospheric ozone layer and alterations to global precipitation patterns.
Since these injections may not completely negate the effects of greenhouse gas emissions, Tilmes and her collaborators assert that well-informed policy choices necessitate a thorough comprehension of the advantages and drawbacks of SAI. They stress the importance of establishing a research and governance framework that fairly represents both the Global South and North to oversee advancements in SAI research and technologies.
“Solar geoengineering research has been conducted for several decades, but there hasn’t been a comprehensive evaluation that gathers all relevant information for policymakers and the public,” remarked NOAA scientist Karen Rosenlof, a co-author of the paper. “Now is the time to carry out such an assessment, encompassing the criteria outlined in this paper, and to repeat this process regularly.”
The paper outlines eight research criteria for evaluating SAI initiatives. These criteria include:
- Technical and economic restrictions
- Cooling capacity
- Fulfillment of climate goals
- Infrastructure for monitoring, detection, and attribution
- Responses to large-scale and regional climate
- Effects on human and natural systems
- Societal risks
- Risk mitigation through governance
The authors suggest producing assessment reports on SAI advancements every few years, ensuring globally representative participation. These criteria could also apply to other proposals for solar radiation modification, such as enhancing marine cloud brightness.
“The purpose of these criteria is to encourage the most effective approaches for the climate while carefully considering the associated benefits and risks, and including the viewpoints of underrepresented communities and the Global South,” Tilmes explained.
