Scientists recommend a checkpoint system to help guide climate engineering research

Research into engineering techniques that might someday be used to artificially cool the planet poses some of the thorniest questions facing today’s society. For climate scientists, this tension is compounded by the lack of a widely accepted supervisory framework to guide their research.

This graph illustrates the six physical science checkpoints proposed by a team of climate researchers as part of a governance framework to guide investigations into marine cloud illumination, a climate intervention technique. In this conceptualization, research proceeds simultaneously on all six checkpoints and on those of the social sciences and ethics, subject to continual re-evaluation as research proceeds. Credit: Michael Diamond and Chelsea Thompson, CIRES / NOAA.

In an opinion article published in the Proceedings of the National Academy of Sciences, a team of scientists led by NOAA and CIRES researchers outlines a framework for evaluating the feasibility of a method for reflecting sunlight called marine cloud illuminance, or MCB. The proposed method would use ocean sea salt particles to increase the reflectivity of low clouds over certain ocean regions. This is one of several methods proposed under consideration as a temporary measure to limit rampant warming.

First, decarbonise …

Climate scientists agree that the most important steps that can be taken to avoid the worst impacts of climate change are decarbonising the economy and preserving and restoring natural carbon-absorbing ecosystems, said lead author Michael Diamond. a CIRES scientist who works at NOAA.


Recent research has shown that “ship tracks” – linear clouds formed by particles emitted by maritime traffic – could be a good analog for a geoengineering technique known as sea cloud clearing. In a new paper, scientists from NOAA, CIRES, NASA and other institutions propose a set of rules for governing how to conduct research on marine cloud illumination and when to stop. Credit: NASA

Unfortunately, current promises to reduce global greenhouse gas emissions are not enough to limit warming to 1.5 degrees C (or 2.7 degrees F). As the impacts on the global climate grow in severity, interest in climate intervention research is expected to increase. A 2021 report published by the National Academies of Science, Engineering and Medicine recommended conducting research on methods of climate intervention and further stated that such research should operate under “robust research governance” to objectively assess its value and risks – governance that does not yet exist.

… but start the necessary research immediately

“The MCB is now being assessed as a potentially viable option, and therefore it is up to us to coordinate the many contributing institutions and create the framework for a future research program,” said NOAA scientist Graham Feingold.

Led by Diamond and Feingold, a team that includes researchers from NCAR, NASA’s Jet Propulsion Laboratory, Brookhaven National Laboratory, Scripps Institution of Oceanography, and the University of Washington, set out ideas for such a facility. They propose a list of six “checkpoints” that should be continuously evaluated when researching marine cloud illumination.

If at any point a research effort were to show that a single aspect of MCB would be technically unfeasible or socially unacceptable, the project would be diverted onto an “exit ramp” leading to redirection or termination of work.

Six roadblocks, explained

Among the physical science checkpoints identified by scientists, researchers should develop sufficient confidence that particles of adequate size can be generated and delivered at the right altitude and, once there, act to form cloudy droplets that disperse sunlight efficiently. . They would also have to demonstrate that the activities of the MCB would not trigger cloudy responses that would substantially offset the brightening effect.

Scientists should also establish that sea clouds that can be brightened occur frequently enough to reduce the global impact of climate change and demonstrate that the cooling effect of the MCB would be measurable to demonstrate that the method works as intended.

Finally, MCB research should clarify the risks of negative impacts on coastal communities and ecosystems and large-scale disruption of atmospheric circulation with unwanted consequences, such as influencing precipitation patterns in vulnerable regions such as the Amazon.

No science in a silo

In addition to addressing scientific gaps, a fair governance structure would incorporate the input of experts in fields outside the physical sciences, such as ethics, sociology, and ecology, into decisions on feasibility and research funding. For example, if researchers reached a point where there was scientific confidence in the predictability of MCB-influenced precipitation changes, a decision on continuing the research would consider how ecological and social impacts affect different communities or regions. .

“Policy makers and potentially affected communities need a seat at the table to ensure that the information scientists generate is usable and relevant to their needs,” said Diamond. Although their paper focuses on the MCB, the scientists support a similar research framework to evaluate the feasibility of other proposals for climate intervention, such as stratospheric aerosol injection, which would cool the planet by spreading millions of tons of reflecting particles. light in the stratosphere, where the earth’s protective ozone layer is located.

“While in an ideal world, the global community would rapidly develop formal governance structures to oversee research and direct funding, the research community must now establish guidelines for itself,” said Diamond.

The research was supported by NOAA’s Earth’s Radiation Budget initiative, CIRES, the National Science Foundation, NASA and the Department of Energy.

For more information, contact Theo Stein, NOAA Communications:


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