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How Brighter Clouds Fight Climate Change (Without Dr. Strangelove)

In 1990, a British cloud physicist named John Latham wrote a letter, [PDF] to the journal Nature, in which he suggested that injecting tiny droplets of water into marine clouds to increase their reflectivity might be a way "to inhibit or neutralize global warming."

And then? "Nothing happened for 10 years except for a couple of angry letters saying it was a horrible thing to play God and why didn’t I go knock on the door of the president and tell him to stop burning fossil fuels," Latham recalls.

But as greenhouse gas emissions kept growing, Latham’s odd idea gained traction. It spawned a succession of peer-reviewed scientific papers, sparked debate in the scientific community and eventually led to the organization of a loosely-knit group of international scientists who now want to see if brightening marine clouds might actually be a feasible way to slow down or stop global warming.

"We’d like to move towards a limited-area field experiment," Latham says.

I met Latham — a leading thinker in the emerging field of geoengineering — last week during a fellowship at the National Center for Atmospheric Research (NCAR). He is 73 years old, semi-retired and unpaid, but passionate about putting his scheme to a test. Latham is collaborating with about two dozen scientists, including "a couple of other geriatrics" (his words, not mine) who play key roles: Stephen Salter is a British engineer who came up with the idea of using unmanned, satellite-controlled, wind-powered ships (below) to travel the oceans and disseminate the seawater, and Armand Neukermans is an inventor and entrepreneur (he helped develop inkjet printer technology at Hewlett Packard) who is working on developing a sprayer able to deliver very fine seawater droplets to the clouds. Interestingly, Neukermans’ research has been supported by a small grant ($300,000) from a fund established by Bill Gates to support innovative climate and energy research.

Latham recognizes that there are dangers in trying to manage, on a global scale, a system as complex as the earth’s climate, the very definition of geoengineering.

"Geoengineering is a horrible word," he said. "It makes people think of Dr. Strangelove.

"I don’t know anyone working in geoengineering who wants deployment to happen," he added.

The trouble is, he said, as greenhouse gas emissions rise — they reached a record high in 2010, according to the International Energy Agency – so does the risk of catastrophic climate change.

“There are no signs that we are behaving responsibly with respect to future generations,” he said. It would be irresponsible, he argues, not to look into alternatives since mitigation has failed, so far, to do the job.

Marine cloud brightening is one way to manage solar radiation; others include injecting sulfate particles into the stratosphere [See my 2010 post “Geoengineering Research Emerges from the Lab”]. Marine clouds cover roughly one-fifth of the Earth’s surface, Latham told me, and they already play a role in keeping the Earth cooler by reflecting the sun’s rays away from Earth. If their surface area could be enlarged, they would be even stronger cooling agents.

Research by Latham and others, using climate models, indicates that “by increasing seeding steadily, we could hold (the Earth’s) temperature more or less constant,” he said. Studies also suggest that cloud brightening could have a greater effect in the polar regions, a good thing because the poles are especially susceptible to global warming. Melting of the Arctic ice caps could have dire effects on sea levels and accelerate warming because the ice has a global cooling effect as a reflector of the sun’s rays.

Latham acknowledges that marine cloud brightening is in no way a cure-all. It will probably alter rainfall patterns. It does nothing to stop ocean acidification, which is caused by CO2 emissions. And cloud behavior, he says, is not as well understood by scientists as you might imagine.

“These clouds, they look very thin, they look very simple, but they are complicated and we need to learn more about them,” he says.

Nor are the engineering issues simple. “Producing the right particles and getting them into the right places is a big problem,” he says.

But marine cloud brightening could be a way to “buy the time needed” to replace the burning of fossil fuels with cleaner energy, he said, and the best way to understand if the strategy can work is to test it.

Latham says his group has in mind a three-day experiment conducted over an area of about 100 square kilometers. Because of its limited size and scope, it would not affect the global climate, he said. It’s entirely unclear who, if anyone, has the authority to regulate such an experiment. And, in any event, Latham said his group won’t be ready to go forward for several years.

What, Lathan was asked, needs to happen to get the U.S. Congress to take the climate crisis seriously?

“Major flooding in New York would probably focus the right attention,” he replied. “I don’t mean to be cynical about that. But Bangladesh could go under with a billion people, and I’m not sure that would provoke the wealthy countries to act.”

I hate to say it, but I think he’s right. Which is why we all need to think hard, and learn more, about geoengineering.

Clouds - CC license by Nicholas_T/Flickr


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