


A technology that could one day cool the planet cleared a key hurdle on Thursday.
At the beginning of April, scientists from the University of Washington began testing a device that sprays tiny sea-salt particles into the air. The initial tests, held on the deck of a decommissioned aircraft carrier in Alameda, Calif., were simply to see if the machine propelled a mist of suitable size. But, in the future, versions of that device could eventually be used to spray particles into clouds, causing them to reflect more sunlight back into space and to temporarily ease global warming.
Two weeks later, Alameda officials ordered the researchers to stop their experiment, citing possible health and environmental risks. The city said it would commission its own assessment to determine whether the experiment posed any threat.
On Thursday evening, Alameda released its findings: The experiment does not generate “a measurable health risk to the surrounding community” or pose a risk to wildlife, the city said.
“The chemical components of the saltwater solution (which is similar to seawater) being sprayed are naturally occurring in the environment,” the report said. It also noted that seawater “is one of the largest sources of natural aerosols in the atmosphere.”
Alameda city councilors plan to meet on June 4 to consider the report and to decide whether to allow the experiment to resume. Researchers had hoped to test the device in different weather conditions over several months or more.