This August, the world’s athletes will gather in Beijing for the 2008 Olympic Games. Although it will be the rainy season there, the weather during opening ceremonies will be perfect. How do we know this? Because the Beijing Weather Modification Office will be working to deliver a rain-free opening day. Thousands of farmers, equipped with rocket launchers, stand ready to fire silver iodide-filled shells at any approaching storm clouds. The idea is to cause the clouds to burst before they float over the capital city. That way they won’t rain on the parade, so to speak.
This cloud-seeding is an example of the Chinese leadership’s belief that central planning can triumph over nature. But when it comes to using technology to control weather and climate, a few scientists and engineers in the United States and elsewhere are working on much more ambitious schemes—with potential worldwide impact—that would make China’s Olympic sunshine feat seem comparatively trivial.
The approach is known as geoengineering, and its focus is on stopping—perhaps even reversing—global climate change. Some of the schemes proposed to lower global temperature read like a science-fiction script: dumping iron into the ocean to suck carbon dioxide out of the air, shielding the Earth from the sun with an enormous orbiting shade, or spewing megatons of light-scattering particles into the air.
Such tampering with nature is viewed with suspicion, even hostility, by scientists who fear it could result in unforeseen danger to the planet. Environmentalists worry, as well, that it could sabotage a global trend toward cutting greenhouse gas emissions through conservation and widely accepted “green” strategies, such as the use of alternative fuels. Others have raised the specter of potential political and military abuses arising from weather technology. This opposition may partly explain why, so far, only a handful of researchers are actually doing geoengineering research. It isn’t formally a part of college curricula.
Yet interest in a technological response has grown as news about global climate change has become more alarming. International negotiations aimed at reducing greenhouse gases haven’t brought impressive results, says Ralph Cicerone, a climate scientist and president of the National Academy of Sciences. Besides, models have shown that the negotiators’ agreed-on targets are hard to achieve merely by cutting carbon emissions. Plus, the Earth is warming at a faster pace than once thought, adding greater urgency.
While government grants are few and published literature on the topic is sparse, private money is starting to flow toward the geoengineering field. In February, 2007, former Vice President Al Gore joined forces with the British entrepreneur Sir Richard Branson to announce the Virgin Earth Challenge, a $25 million prize for a new technology that will remove greenhouse gases from the atmosphere.
Old Theory, New Urgency
The idea of using technology actively to change the Earth’s climate is not new. In 1962, when global warming was little understood, Harry Wexler, chief of the U.S. Weather Bureau’s Scientific Services Division, described how the Earth could be cooled using a dust ring launched into orbit or warmed using ice crystals sent aloft by exploding hydrogen bombs. In 1965, an advisory committee reported to President Lyndon Johnson about the threat of CO2-driven climate change. Interestingly, the only solution discussed in that report was geoengineering, with no mention of reducing fossil fuel use, according to David Keith, director of the Energy and Environmental Systems Group at the University of Calgary in Alberta.
Yet as scientists learned more about the effect of greenhouse gases on the environment, cutting carbon emissions became the most widely accepted response, one enshrined in the 1997 Kyoto Protocol. During meetings of the United Nations-sponsored Intergovernmental Panel on Climate Change, U.S. representatives were rebuffed when they sought to promote geoengineering technologies, according to Ken Caldeira, a climate scientist at the Carnegie Institution of Washington’s Department of Global Ecology at Stanford University.
The taboo regarding geoengineering extended to peer reviews of scientific articles, as became clear when Paul Crutzen, of the Max Planck Institute for Chemistry in Germany, submitted an essay to the journal Climatic Change in 2006. The essay discussed the feasibility and environmental consequences of injecting sulfur into the atmosphere to reflect sunlight away from Earth. It also advocated further research. The fact that Crutzen won a Nobel Prize in 1995 for work on the chemistry of ozone depletion elevated the paper’s importance.
The article “attracted lots of negative comments,” says Cicerone, who was consulted by the editor of the journal on how to handle it, “The reactions were very angry.” Some reviewers feared that “to write about [geoengineering] was very dangerous because it could give the public the erroneous view that the community knows how to deal with climate change with technology,” he said. These reviewers also opposed geoengineering approaches in principle due to their possible unintended side effects.
The editor packaged a revised version of Crutzen’s essay together with several others offering different points of view. In one, Lennart Bengtsson of Britain’s University of Reading, former director of another branch of the Max Planck Society, the Institute for Meteorology, argued that a geoengineering project would have to continue for a millennium in order to reduce greenhouse gases to an acceptable level. Making a long-term commitment toward developing alternative energy sources would be more feasible, he wrote.
Jeffrey Kiehl of the National Center for Atmospheric Research in Boulder, Colo., supported Crutzen’s call for better modeling studies. “But my concern is that all models have their limitations,” he wrote. “When will we know a model is ‘good enough’ to go out and perform a real experiment?” He also expressed concern that such work would send the wrong message—that the developed world’s “insatiable use of energy” isn’t really a problem.
In his own essay for the same issue of Climatic Change, Cicerone argued that research into geoengineering was important for its own sake, regardless of whether it resulted in actual plans. “Research is needed to reduce ignorance,” he wrote, “and it is likely that gaining an acceptable amount of knowledge before intervention will take many years. Freedom of inquiry itself has moral value.”
Vast Possibilities, Unproven Science
The magnitude of what science theoretically might produce—and the accompanying dangers—are distilled in a joke told at a seminar 20 years ago by the late John Martin, then director of the Moss Landing Marine Laboratories in California: “Give me half a tanker of iron, and I’ll give you the next ice age.” He uttered the line in his “best Dr. Strangelove accent,” Martin said later, indicating he wasn’t serious. Even so, the quote vividly captured his hypothesis that sprinkling small amounts of iron into certain areas of the ocean would cause phytoplankton to bloom and thus take a significant amount of carbon dioxide out of the atmosphere. When the organisms died and sank to the bottom of the ocean, they would take that carbon with them, sequestering it. The absence of carbon dioxide in the upper atmosphere would reverse the greenhouse effect, causing the earth to chill.
Early models suggested that fertilizing the Southern Ocean in this way could wipe out about 10 to 25 percent of the world’s carbon emissions each year. But experiments done since then have cast some doubt on whether the technique would be that efficient or effective. Dumping iron into the ocean does cause plankton blooms, but as other organisms feast on the plankton, a lot of carbon dioxide gets released back to the surface. Only a small amount of carbon actually sinks to the seafloor and is stashed away.
Now, private firms like Planktos and Climos, both headquartered in the San Francisco Bay Area, are doing iron fertilization experiments of their own. Their goal is to cash in on the carbon offset market, through which businesses would pay them to sequester carbon instead of reducing emissions themselves.
Researchers are also looking at potential storage sites for carbon on land. Carbon dioxide could be removed chemically from the air or captured right as it is emitted from a power plant. The gas could then be pumped underground into geological formations such as otherwise unusable coal seams, spent gas and oil fields, and deep saltwater aquifers. Technology to do this currently exists, though researchers are continuing to study how permanent such storage sites are and how carbon dioxide migrates within them.
Some scientists don’t consider carbon sequestration to fall under the rubric of geoengineering because it doesn’t have the “quick fix” aspect usually associated with the term. The effects of reducing atmospheric carbon dioxide would take decades, Caldeira says. It would be good for the long-term health of the planet, but not useful as an immediate solution.
Other proposed geoengineering strategies involve altering the Earth’s albedo, or the extent to which the planet reflects sunlight. This idea was mentioned as early as the 1965 report to President Johnson. If sunlight could be reflected away from Earth, global temperatures should drop, according to the theory. Modeling studies done by Caldeira and colleagues show that even if carbon dioxide levels in the atmosphere doubled, cutting sunlight by just 1.8 percent would prevent global temperature from rising (although it would be a couple of degrees Celsius warmer over the poles).
Actual evidence of this result emerged in 1991 when Mount Pinatubo in the Philippines erupted. The volcano spewed millions of tons of ash and sulfur dioxide into the atmosphere, which was converted to sulfate particles in the stratosphere. Sulfate affects the reflective properties of clouds so that they scatter more sunlight. The average global temperature ended up dropping about half a degree Celsius in the year following the eruption.
Researchers have proposed creating an “artificial volcano effect” by deliberately shooting aerosols into the stratosphere with artillery guns or flying them there on aircraft or balloons. The advantage of schemes like these is that they could be carried out quickly and cheaply, and the effects would be seen right away—characteristics that make them appropriate as an emergency response, Caldeira says.
But there are obvious downsides to putting sulfur dioxide into the atmosphere. It’s a pollutant and causes acid rain if it gets into the lower portion of Earth’s atmosphere. That’s why some scientists are thinking about deflecting sunlight with other materials. One possibility is to send giant sprays of seawater skyward, increasing the moisture in reflective stratocumulus clouds. In another, Keith and his colleagues are developing an idea to levitate nano-engineered sunlight-scattering particles into the mesosphere, 30 to 50 miles up. These particles could be engineered so that they heat up more on one side than the other. The temperature gradient would create a force to push them upward, a natural process known as photophoresis. This strategy “would allow you to have particles that have much longer lifetimes,” Keith says, and to concentrate them over the poles, where climate engineering is needed most.
In the Nov. 14, 2006, Proceedings of the National Academy of Sciences, Roger Angel of the University of Arizona described a geoengineering scheme to launch trillions of small, lightweight spacecraft into orbit between the Earth and the sun. The spacecraft would be made of a thin, transparent material and arrange themselves into a long cylinder that would screen out a portion of the sun’s rays—a vast sunshade. “The concept builds on existing technologies,” he says. “It seems feasible that it could be developed and deployed in about 25 years, at a cost of a few trillion dollars. With care, the solar shade should last about 50 years.”
A Sign of Federal Interest
In July, Angel won a grant from NASA’s Institute for Advanced Concepts to develop the space sunshade, but it’s one of only a few geoengineering proposals that has received federal funding. Another grant has been awarded to Alan Robock, a meteorologist at Rutgers University. He and his team received a three-year National Science Foundation grant to model specific geoengineering schemes; they plan to focus on the injection of aerosols into the atmosphere. The money will allow them to examine the ethics of such schemes, too.
The grant to Robock may be a tangible sign that geoengineering research is becoming more widely accepted. Cicerone notes that the NSF generally follows the lead of the research community. If NSF gets a lot of proposals for geoengineering, it will respond, he says. In the period since Crutzen’s ideas sparked a furor, Cicerone says, he is starting to sense a shift toward grudging acceptance of geoengineering among scientists. “They’re saying, ‘I may not like it, but we should research it,’” he says.
The support given to geoengineering by Al Gore will likely increase public awareness, particularly given Gore’s enhanced stature as a Nobel prizewinner. The technology prize he is cosponsoring with Branson is aimed at encouraging further innovation. The winning design must result in a net removal of greenhouse gases each year for at least 10 years and contribute to the stability of the Earth’s climate.
‘I Feel Guilty’
But the many questions still surrounding this science were evident at a December meeting of the American Geophysical Union in San Francisco, where Caldeira, Robock, and Richard Turco of the University of California at Los Angeles chaired a session on geoengineering. During a press conference, they emphasized the need to develop research programs and improve the quality of the work being done. The three scientists also showed they were keenly aware of the social and ethical doubts that persist. Robock’s AGU presentation included a list he had compiled of “20 reasons why geoengineering might be a bad idea.”
About his own NSF grant, Robock says, “I even feel guilty spending society’s resources on this.” But he adds that society can afford both to examine potential technological solutions to climate change and to reducing greenhouse gas emissions. Turco, for his part, says geoengineering proposals can’t be considered separately from their cost, risk, ethics, legality, or political feasibility. “In this context of geoengineering and global climate change, these are all important attributes--not just the science.”
Others have raised concern about potential geopolitical contests over control of weather patterns. Writing in the Wilson Quarterly, James R. Fleming, professor of science, technology and society at Colby College, traces a long history of U.S. officials contemplating the possible uses of weather modification in warfare. In an interview, he said, “Ethically, one of the big questions is, ‘Who has the right to do this -- to modify global climate?...Where is the thermostat going to be? Who’s going to set the temperature?’ There’s a pretty solid list of ethical questions that are simply not properly being addressed.” Heavy experimentation might run afoul of some international treaties, he noted.
Even proponents of geoengineering research seem to agree that it’s not a panacea. Nations must continue to reduce carbon emissions to have any hope of keeping global temperature in check.
Caldeira thinks a way around the varied dilemmas posed by geoengineering is for proponents to frame it as an emergency response to be held in reserve in the event of catastrophe—“like flood and fire insurance. You have it, but you hope you don’t need it.” If climate change is blamed for causing, say, a drought that leads to a famine, the world might want to have tools on hand to prevent widespread human misery or death. Since developing such tools would likely take years, if not decades, the research needs to start now, proponents say.
It’s also important to know if a scheme is not going to work before it is hastily attempted, Caldeira says. “There’s a real downside to unpreparedness,” he notes. “It’s possible that the schemes we’re talking about will just screw up the planet even more…There’s a tendency for politicians to want to act. And it’s important that they have the scientific information to have some idea whether their proposed plan would just make things worse or actually could alleviate some of the problems.”
To keep the quality of geoengineering research high, “scientists will have to make an attitude adjustment,” Cicerone says. They will have to be willing to review each other’s work objectively, in spite of where they stand on the issue ideologically. As difficult as that might be, the field won’t move forward otherwise.
Corinna Wu is a freelance journalist based in Oakland, Calif.