The fate of the nation’s first outdoor experiment of the potential to limit global warming by altering clouds will be determined this week by a handful of local officials in the San Francisco Bay Area.
But before the city council of Alameda, elected by a community of 77,000 people, decides on whether to allow the resumption of the internationally significant research, it will discuss replacing the roof of a senior center and other municipal issues. The consideration of the marine cloud brightening study — official, agenda item “7-B” — stands to be one of the first consequential public hearings on solar geoengineering in the nation.
The unusual situation set to play out Tuesday night illustrates just how hard it is to test technologies that might be used in the future to brighten clouds or spray aerosols in the stratosphere — promising but ethically fraught ways to turn down the planet’s thermostat by reflecting sunlight back into space. The concept of solar geoengineering is attracting more interest from philanthropists and policymakers as emissions and temperatures continue to rise — and now, from local leaders who halted the cloud research last month because, they said, it lacked necessary permits.
“Cancellation of this small experiment could add to public confusion about climate intervention research more broadly,” said Frank Keutsch, an atmospheric science professor at Harvard University, referring to the secretive study unveiled by University of Washington researchers earlier this year.
Such a decision would “jeopardize future experiments elsewhere that are needed to provide insights into the risks of climate intervention as well as its efficacy in reducing impacts of climate change,” he told E&E News.
Keutsch led a separate solar geoengineering project, known as SCoPEx, that sought to consider the implications of limiting global temperatures by spraying reflective materials into the stratosphere.
That project never got off the ground due to intense opposition from environmental groups and Indigenous communities in northern Sweden, where its initial tests were to take place in 2021. The opponents objected to the expected side effects of solar geoengineering — such as changing weather patterns and potentially spiking temperatures if spraying ended abruptly — and the project’s limited engagement with nearby communities.
The University of Washington’s marine cloud brightening experiment has encountered similar challenges since it was launched in April, to the surprise of local officials.
The project, named Coastal Atmospheric Aerosol Research and Engagement, or CAARE, used specially built machines that resemble snow cannons to shoot trillions of sea salt particles into the sky in an effort to increase the density — and reflective capacity — of marine clouds. Initial rounds of testing took place on the sprawling deck of the USS Hornet, a retired aircraft carrier that now serves as a museum in Alameda.
A consulting firm the university hired to evaluate potential regulatory challenges concluded in March that the museum’s existing permits “support the operation of this limited-scale Study.”
But Alameda officials disagreed. Last month, they ordered the university to halt the experiment until it receives explicit authorization from the city.
The future of the project is now one of more than a dozen agenda items the Alameda council will consider Tuesday evening.
Rob Wood and Sarah Doherty, the University of Washington researchers leading the CAARE project, said in a statement that they welcomed the scrutiny.
“This type of review was not unexpected given that the approach in undertaking the studies and engaging with the public is something new,” they said. “We appreciate the care taken by the City of Alameda on this effort and support their approach fully.”
Battle lines drawn
Ahead of the high-stakes municipal meeting, the city hired independent experts to review the health and safety implications of the project and sought feedback from the community.
The response so far has been divided. Experts and scientists largely support the study, with opposition coming from some of the same environmental groups that helped kill SCoPEx, the defunct project in Sweden that stands for Stratospheric Controlled Perturbation Experiment.
Research on solar geoengineering “is a growing part of mainstream climate science,” wrote James Hurrell, an atmospheric science professor at Colorado State University, in a letter to Alameda officials. Hurrell, who disclosed previously working with some of the University of Washington researchers, concluded that their new study is “scientifically sound … and the data it will produce will be invaluable to researchers across the globe.”
At the local level, consultants hired by the city found the tests would not harm the environment, sensitive species or the surrounding community.
Yet some environmental groups remain unconvinced.
“We call on the Alameda City Council to put an end to the experiment on the USS Hornet Museum and put in place legislation to prevent further such outdoor experiments from taking place in your jurisdiction,” Eesha Rangani, a representative of the Hands Off Mother Earth Alliance, wrote to the council. “Allowing the experiment to take place would risk putting us on a slippery slope toward the development and deployment of this technology while also serving to legitimize these highly controversial climate manipulations.”
The so-called HOME Alliance opposes all geoengineering research and includes environmental and human rights groups such as the Center for International Environmental Law, Friends of the Earth, Carbon Market Watch and Amnesty International.
Whatever happens at the city council meeting, the outcome will reverberate far beyond the Bay area, according to Keutsch, the Harvard scientist.
“While climate intervention is no substitute for urgently reducing fossil fuel emissions, unfortunately the world is far off-track from reducing emissions enough to prevent potentially catastrophic warming, so we must explore all possible options that can address climate impacts,” he said in an email. “It is important this experiment resume.”
