It may sound like science fiction, but researchers are getting closer to making it possible to geoengineer the climate.
“Since the ocean is the darkest surface on the planet, if we can make clouds over the ocean brighter, we reflect more solar radiation and we cool the planet,” says Tom Ackerman, a UW atmospheric sciences professor who has been working on geoengineering the climate for several years.
His team thinks they can brighten clouds by spraying saltwater into the atmosphere. Ackerman says they have developed a nozzle that can spray about a trillion tiny particles a second of saltwater into the atmosphere.
The team wants to figure out if it will actually work by building a sprayer and testing it off the coast of California. They need funding to upscale the nozzle and test their hypotheses.
Ackerman describes the process as a very early phase of field work to make sure the team's basic assumptions and modeling are accurate.
“These experiments are so small-scale that they have no impact on local climate, let alone global climate,” he says. “And we’re using saltwater, so it’s a very benign experiment. Whatever salt we put in the atmosphere over the ocean eventually ends up going back into the ocean where it came from.”
Ackerman says he’s “agnostic” about whether geoengineering should ultimately be part of society’s toolkit for addressing climate change. But he wants to know if the cloud brightening technique could work.
Even at full scale, he says their technique would be a temporary stopgap to mitigate global warming and stave off the worst effects. People would still have to reduce their emissions.
Another team at Harvard is close to field testing a cooling technique that would attempt to dim the sun’s radiation by spraying particles into the stratosphere that mimic some of the natural effects of sulfur after volcanic eruptions. Other techniques would involve finding ways to remove excess carbon dioxide from the atmosphere.
But huge questions remain about who would regulate such tinkering with the atmosphere and how. The ethics of the field are the subject of the two-day symposium going at the University of Washington.
Stephen Gardiner is a philosophy professor in the Program on Values in Society. He helped organize the symposium to explore some of the bigger questions beyond the science.
“How would you govern it, who would do it? How would they do it? Who would they be accountable to? What would make doing geoengineering legitimate from the political point of view, justifiable to those affected by it?” Gardiner asks.
“Nobody’s really thought about how to put in place institutions that could govern that.”
Gardiner says, by definition, the effects would be global and could last hundreds or even thousands of years. Along with Ackerman, he co-teaches a course on the science, ethics and policy of geoengineering. They are offering the course again this coming winter.
Their symposium is funded by the National Science Foundation. A public panel discussion with the organizers takes place on Thursday evening.