Cool planet by growing plankton in oceans?

Scientists report gas emitted by creatures could create cloud cover
Updated: 4:25 p.m. ET Aug. 20, 2007

SOCORRO, N.M. - A New Mexico Tech scientist believes he has found a way to head off dangerous climate change. Oliver Wingenter said the idea is simple — fertilize the ocean so that more plankton can grow.
Plankton growing in the ocean emits a gas known as dimethyl sulfide, or DMS, that once in the atmosphere, helps spur cloud formation. That, in turn, would cool the planet and offset some of the global warming caused by human emitted greenhouse gases, he said.
World governments are looking for ways to cut emissions and head off the worst damage such change might cause. Efforts are having limited success, though, so some scientists have begun to advocate counter measures to offset the warming.
Wingenter said his idea has been a tough sell, and it has been a struggle to win funding to further pursue the research.
But as Earth inches toward a climate tipping point of runaway warming, Wingenter said his technique could be used to buy time to make societal changes necessary to cut greenhouse gas emissions.
"I'm just hoping that this is something that will give us a little more time," he said.
He and a pair of colleagues published the information last month in the scientific journal, "Atmospheric Environment."
Idea born at seaWingenter said he came up with idea while spending seven weeks at sea in early 2002, collecting atmospheric data as part of a major climate change research experiment.
At the time, DMS and cloud formation were the furthest thing from the scientists' minds. They were trying to see if fertilizing plankton in the planet's southern oceans could slow down global warming in an entirely different way — by coaxing the ocean plankton to gobble greenhouse gases out of the atmosphere.
Greenhouse gases, primarily carbon dioxide coming out of the tailpipes of cars and exhaust stacks of factories, are changing Earth's climate, most scientists agree.
But the potential for using plankton to scrub greenhouse gases out of the atmosphere remains uncertain.
In pursuing his idea, Wingenter is entering a scientific political minefield known as geo-engineering.
The most widely discussed geo-engineering proposal involves a fleet of jets spewing aerosols that would deflect the sun's rays, cooling the planet in the process.
Other suggestions include launching giant mirrors into space to block some of the sun's light.
Risks citedOne risk, said Ken Caldeira, an expert in the field at the Carnegie Institution in California, is that geo-engineering might be used as an excuse to avoid cutting greenhouse gas emissions.
But by far the less risky course is to minimize greenhouse gas emissions in the first place, he said.
Caldeira said that, in principle, Wingenter's idea looks like it might work. But he suggested a cautious approach, with more research to understand the effect fertilization might have on both ocean and climate.
"It might be relatively benign," he said. "It might not. We just don't know."