Can whiter clouds reduce global warming?

Can whiter clouds slow global warming?

A grant from Bill Gates is helping researchers explore the possibility that making clouds whiter and more reflective by spraying them with a fine seawater mist could help block the sun’s rays and send them back into space.

Cloud whitening builds on the natural cloud-forming process, says Silicon Valley inventor Armand Neukermans, who received the funding to test if the concept is doable.

When water vapor in cloud-forming regions encounters sea salt crystals it condenses around them, forming tiny droplets, he explains. Together, many droplets diffuse sunlight and make a cloud whiter.

Proponents say the research is needed because of society’s failure to reduce carbon dioxide emissions, which are thought to be causing global warming, according to the National Oceanic and Atmospheric Administration. The 2000-09 decade was the warmest since record keeping began in 1880, NOAA reports.

Critics call the research dangerous.

“The assumption is we can play God with the Earth’s ecosystem,” says Erich Pica, president of Friends of the Earth.

The solution to global warming is to reduce fossil fuel use and carbon dioxide production, Pica says. “Everything else is just a distraction.”

Gates has been studying technologies for reducing carbon dioxide emissions and geo-engineering techniques such as cloud whitening for several years, says Ken Caldeira of the Carnegie Institution for Science’s Department of Global Ecology.

Caldeira and a colleague at the University of Calgary administer $4.5 million that Gates provided for such research. Caldeira awarded $300,000 of that money for laboratory research by a team of engineers led by Neukermans. Other researchers are looking for additional ways to whiten clouds, and at designs for unmanned boats to carry the spray mechanisms, says cloud physicist John Latham of the National Center for Atmospheric Research in Boulder, Colo. Latham first suggested cloud whitening as a way to counter global warming in 1990, according to Rasch.

Latham envisions hundreds of wind-powered boats generating the sea spray and a combination of planes and satellites to measure and control the clouds’ moisture content, reflected solar energy and surface temperature.

He estimates the project, which he says would require international approval before it were launched, would cost about $4.5 billion and buy the planet 30 to 60 years to develop a more permanent solution.

There are risks to spraying seawater into the air, says Dan Murphy, a research scientist at the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory in Boulder. Reducing the sunlight entering the ocean will reduce the evaporation of water and make less rainfall, which could lead to droughts, he says.

Such worries prompted the Montreal-based environmental group ETC Group to launch a campaign called “Hands off Mother Earth!” that counts dozens of member organizations around the world and urges governments to ban real-world geo-engineering trials.

Global warming was caused by “the scientific, corporate and political establishment of developed countries,” ETC Group’s Diana Bronson says.

“To now think those same people will correct the climate crisis and the biosphere is a little bit naïve,” Bronson says.

Kert Davies, research director for the environmental group Greenpeace, worries about unintended consequences but he can imagine a reasonable use for cloud whitening.

“In an emergency situation during summer when the ice cap is melting you might want to think about putting up a cloud,” Davies says. “But as a global strategy it’s just a Band-Aid.”

source: USAtoday.com

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