Dismissed for decades as a climate-controlling scheme that could do the planet more harm than good, geoengineering is getting a new look by both scientists and the public.
Broadly defined, geoengineering is a global effort designed to either cool the planet or reflect sunlight, rather than reducing society's output of greenhouse gas emissions that are causing climate change in the first place.
Last week, a California businessman got in hot water after it was disclosed that he was seeding parts of the Pacific Ocean with iron in an attempt boost plankton populations. His goal was to both increase the number of spawning salmon, as well as capture more carbon dioxide from the atmosphere.
Although he wasn't authorized to perform the experiment, the businessman, Russ George, was inadvertently helped out by the National Oceanic and Atmospheric Administration, who provided him with drifting buoys to help measure his project, which occurred in July.
Today, a researcher at the California Institute of Technology says that a careful seeding of the upper atmosphere (above 50,000 feet) with tiny sulfate particles could be a viable climate-cooling solution by reflecting sunlight back into space.
The study, published in the journal Nature Climate Change, tested various scenarios for atmospheric seeding using computer models. The paper concludes that by spreading these particles -- the same kind spewed out by volcanoes -- into select areas of the stratosphere, the resulting effects of the cooling would be 30 percent better than if the entire planet had an even distribution of particles.
Because turning down the global thermostat leads to different effects in different places (a cooler North America might result in more monsoons in India), "if you tailor the distribution, you can reduce the worse-off location by 30 percent, and everyone's climate is closer to what they want," said Douglas G. MacMartin, a senior research associate at CalTech's Department of Control and Dynamical Systems.
More and more scientists are starting to consider the possibility of some form of geoengineering, MacMartin said, and that it's important to test any possible plan out ahead of time.
In the past, proponents of geo-engineering have proposed things like orbiting space-based sunshades to shield the Earth, putting up huge reflective balloons or dumping tons of rust particles into the ocean to capture CO2. That happened in 1991 when Mt. Pinatubo erupted and dumped an estimated 40,000 tons of iron dust into the world's oceans, which did in fact slightly lower carbon levels.
Of course, it's never been tried on a global scale on purpose.
"There are lots of reasons why geo-engineering is not an ideal solution," said MacMartin. "Certainly emissions reductions are a lot safer. But we don't know all the consequences of geoengineering are, and what the consequences that not doing it are. We might wind up in situation that some form of geoengineering is better than not doing it."
That might have been the working theory behind George's plan, which was first revealed in The Guardian.
George said that he was the world's leading champion of geo-engineering, and was also planning to profit from his plan to dump 100 metric tons of iron sulfate in the ocean. The Canadian tribal group who contracted with George said on Friday that they weren't too happy about the plan.
"The consequences of tampering with nature at this scale are not predictable and pose unacceptable risks to the marine environment," read the statement from the Council of Haida Nation. "Our people along with the rest of humanity depend on the oceans and cannot leave the fate of the oceans to the whim of the few."
Rutgers University climate scientist professor Al Robock remains skeptical of global climate-tweaking projects for both scientific and ethical reasons. "We have to learn what the benefits and risks of proposed schemes are," he said.
Seeding the stratosphere can also damage the Earth's protective ozone layer, although the exact amount isn't clear. That was another side effect of the Pinatubo eruption.
The condemnations coming out around the recent unauthorized ocean-seeding has probably given geoengineering a bad name for now, Robock said.
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