Officials in Alameda, California, have told scientists that a device could one day be used to artificially cool the Earth by brightening clouds and reflecting global warming sunlight back into space. I was instructed to stop the experiment.
The experiment, conducted by researchers at the University of Washington, sprayed tiny sea salt particles across the flight deck of the retired aircraft carrier Hornet, which is docked at Alameda in San Francisco Bay. A version of that device could eventually be used to spray the material skyward, brightening clouds and reflecting more sunlight to help fight global warming.
The experiment, which began April 2, was the first time in the United States that researchers had tested such a device outdoors. However, on May 4, the city of Alameda wrote on its Facebook page that it had instructed researchers to halt the experiment, citing potential health concerns.
“City staff is working with a team of biological hazard consultants to independently assess the health and environmental safety of this particular experiment,” officials wrote. “The city is evaluating the chemicals in the spray to determine whether it poses a risk to people or animals, either by inhalation in the form of an aerosol or by landing on the ground or in the bay.”
“At this time, there is no evidence that the droplets from the previous test posed a threat to human health or the environment,” the city statement said.
The University of Washington's Marine Cloud Brightening Research Program, which is conducting the experiment, said in a statement Monday that the salt particles released are “well below established thresholds for environmental and human health impacts of release.” Announced.
Alameda officials were informed about the study before work began and requested a more detailed investigation after the study began receiving media attention, the statement said. “We are happy to support their review and it has been a very constructive process so far,” it said in a statement. “We appreciate the City of Alameda’s thoughtfulness in this effort and fully support their approach.”
“There was no requirement to do anything that hadn't been done beforehand,” said Sarah Dougherty, an atmospheric scientist at the University of Washington and director of the Ocean Cloud Brightening Program.
Dr Doherty said her team voluntarily paused the study after local authorities raised concerns. He said the researchers were able to obtain some useful data during the short period that the experiment was underway, but further measurements are needed.
Sarah Henry, a spokeswoman for the city of Alameda, said USS Hornet officials told the city manager in November that the experiment involved climate change science and specifically that “the length of the flight deck “We will study the patterns of clouds by turning them into mist.” He said Hornet did not provide any additional information at the time and the city did not request any information.
The City Council will meet June 4 to discuss the study, Henry said. “They may decide it doesn't pose any risk and allow it to move forward,” she said.
Brightening clouds is one of several ideas for channeling solar energy back into space, sometimes called solar modification, solar geoengineering, or climate intervention.
This idea is built on a scientific concept called the Toomey effect. That is, many small droplets reflect more sunlight than fewer large droplets. Therefore, spraying vast amounts of tiny aerosols into the sky to form large numbers of tiny droplets can change the reflective properties of clouds.
Compared to other options, such as injecting aerosols into the stratosphere, the brightening of ocean clouds is localized and relatively harmless sea salt aerosols are used instead of other chemicals.
Nevertheless, this concept suggests that research into artificially cooling the Earth will divert attention and resources from efforts to address the root cause of climate change, which is the continued burning of fossil fuels such as oil, coal, and petroleum. This has sparked concern from some environmental activists who fear that it could lead to environmental problems. Natural gas.
Local environmental changes are also a concern. Dr Doherty said there were potential side effects that still needed to be studied, including changes in ocean circulation patterns and temperatures that could negatively impact fisheries. As the clouds lighten, precipitation patterns may also change, resulting in less rain in some places and more in others.
But as global greenhouse gas emissions continue to rise, causing hurricanes, wildfires, floods, heat waves, and other forms of climate change to become more severe, more frequent, or both, The idea of cooling has recently received new attention and funding.
Doherty and colleagues stressed that studying cloud brightness should not be seen as an alternative to reducing emissions, but rather a strategy that may someday be needed to buy time until emissions are reduced. .
