Faced with roadblocks to reducing greenhouse gas emissions via globally meaningful regulations or carbon pricing schemes, some scientists say it’s time to consider even more drastic human intervention.

As it looks increasingly unlikely that the world will adopt a political and economic approach to reducing greenhouse gas emissions—primarily carbon dioxide—what was once regarded as a far-fetched, fringe idea is generating increased mainstream interest. The popular term is “geoengineering,” although the chief proponent prefers “solar radiation management” or SRM.

Initially, the attention of those focused on preventing or managing global warming focused on the political and economic approach: How do we get the governments of the world to find ways to stop putting more carbon dioxide and other greenhouse gases into the atmosphere? But that strategy has become mired in international politics with little prospects of effective action.

What’s left? Attention is increasingly focusing on ways to cool the planet by blocking some sunlight from reaching Earth, either by preventing it from getting to Earth or reflecting it back toward the sun. It’s no longer a fantastic notion but is becoming a mainstream approach.

Add Another Gas

The SRM acronym is the creation of David Keith, the Gordon McKay Professor of Applied Physics at Harvard’s School of Engineering and Applied Sciences (and also a professor of public policy at Harvard’s Kennedy School of Government). His recent book, A Case for Climate Engineering (MIT Press, 2013), argues that research should begin now on ways to slow global warming by engineering practices, rather than by what appear to be dead-end policy directives and regulatory initiatives.

Keith is humble about the path he urges. “The bitter truth,” Keith writes, “is that the world’s efforts to cut emissions have (with a few exceptions) amounted to a phony war of bold exhortation and symbolic action. It’s tempting to assert emissions cuts are impossible and that we must look to alternatives like geoengineering. This is double wrong. First, solar geoengineering may reduce risks in the short term but it cannot get us out of the long-term need to cut emissions. Second, to assert that emissions cannot be cut is to take human agency—and responsibility—out of the picture as if emissions were coming from some species other than our own.”

Keith wants to test a managed approach to using sulfate aerosols released into the atmosphere: a controlled attempt to mimic what nature has already done repeatedly with major volcanic eruptions—such as the Mount Pinatubo eruption in the Philippines in 1991—that cool the planet. (The NASA image at the top of this article shows the atmosphere less than two months after the Pinatubo eruption; two dark layers of aerosols make distinct boundaries in the atmosphere.) “The best case for taking solar geoengineering seriously,” he said in a Washington Post interview last year, “is that the balance of scientific evidence we have—from the same kind of climate models and other science that we use to understand climate change—suggests that these technologies could, if used carefully, significantly reduce climate risk. Full stop.”

Keith says the technologies he’s explored, injecting sulfur dioxide into the atmosphere or adding fine sea salt to marine clouds to make them whiter and change the solar albedo, or reflectivity, “appear to provide a pathway by which we could substantially reduce climate risks over the next half-century. That means reducing the risks of sea-level rise, reducing the risks of stress for crops of people in the poorest and hottest parts of the world.”

Keith says he sees geoengineering as a short-term way to buy time. “Nothing changes the fact that in the long run, the only way to manage carbon risk is to stop emitting carbon dioxide. But, similarly, nothing we know about cutting carbon dioxide emissions says that’s going to help us deal with the risk of CO2 that’s already in the atmosphere.” He says he sees “cutting emissions as a long-term solution and geoengineering as more of a short-term solution.”

In his book, Keith says, “Geoengineering complements emissions reductions. Cutting emissions reduces the long run risk by stopping the accumulation of carbon, while geoengineering—if it works as expected—will mask risks in the short run (in the slow moving world of carbon and climate short run means the next half century).

“But geoengineering cannot eliminate the underlying risk that comes from humanity’s rapid (in geological time) transfer of carbon from underground reservoirs to the atmosphere. It’s hard to overstate the importance of geoengineering’s ability to reduce risk for current generations as there are no other methods that can reduce these risks significantly in the next half century.”

The Reflection Option

Another approach to geoengineering comes from Scottish engineer Stephen Salter, emeritus professor of engineering design at the University of Edinburgh. Salter is the inventor of the “Salter Duck,” a device for turning ocean wave motion into electricity (see sidebar). His latest idea, which has won substantial support, including investment from Microsoft billionaire Bill Gates, is to mount a fleet of ships to spray seawater into the atmosphere to change the albedo of clouds to reflect sunlight back into space (Figure 1). (Keith also has money from Gates.)

1. Cloud brightening. When aerosol particles from ship exhaust enter the lower atmosphere, marine stratocumulus clouds are brightened, leaving “ship tracks” visible in satellite images. Scientists at Pacific Northwest National Laboratory and the National Oceanic and Atmospheric Administration (NOAA) are among those studying the effects of particle injection to evaluate whether this technique could be used to offset some effects of global climate change. Courtesy: Jeff Schmaltz, MODIS Rapid Response Team, NASA/Goddard Space Flight Center
Salter’s DucksBack in 1974, amidst the Arab oil embargo, University of Edinburgh engineer Stephen Salter came up with an interesting idea for how to generate electricity from ocean waves. It was a pear-shaped device about the size of a house that floated in the water. As the waves hit it, the gyroscopes inside the device converted the wave energy into rotation, which could then be used to generate electricity. Each duck could generate up to 6 MW, and the plan was to install them in groups of a dozen or so (perhaps to be known as flocks). A small-scale prototype was built in 1976.Initial estimates from the government concluded that “Salter’s ducks” were far too expensive to compete with even the most expensive generation of the time, nuclear power.

As oil prices fell in the 1980s, the British government abandoned its wave energy program. It later turned out that the government had overestimated the costs by a factor of 10. In an article in 2008, The Economist magazine said, “The reasons for this were not made public, but it is widely believed to have happened after lobbying by the nuclear industry. In testimony to a House of Lords committee in 1988, Dr Salter said that an accurate evaluation of the potential of new energy sources would be possible only when ‘the control of renewable energy projects is completely removed from nuclear influences.’”

Gates provided funds for prolific inventor Armand Neukermans to test the idea of altering the reflectivity of clouds to deflect sunlight away from the planet. Neukermans calls it “cloud brightening.”

“He more or less showed it was feasible to my satisfaction,” said Ken Caldeira, a prominent climate scientist who advises Gates on global warming issues.

Jane Long, a former top executive at the Department of Energy’s Lawrence Livermore National Laboratory, said, “If we have to intervene, we should be doing the research now, because these ideas are extremely complicated and extremely risky. I hope we never have to do it, but I think it’s irresponsible not to understand as much as we possibly can in case we need it.”

Long was the co-chair of a Bipartisan Policy Center task force, which three years ago concluded that “the federal government should embark on a focused and systematic program of research about climate remediation. The federal government is the only entity that has the incentive, responsibility, and capacity to run a broad, systematic and effective program; it can also play an important role in effectively establishing international research norms.”

Not So Fast

But that’s not a unanimous opinion by any reckoning.

The enthusiasm for geoengineering, even for small-scale research, is dangerous techno-optimism that risks turning over the state of the climate to business interests, says Clive Hamilton, professor of public ethics at Charles Sturt University in Australia and also the author of a recent book, Earthmasters: The Dawn of the Age of Climate Engineering (Yale University Press, 2103). He argues that research into geoengineering would threaten the moral imperative to protect the Earth. He writes that geoengineering “actually represents a profound change in the relationship of Homo sapiens to the Earth. In the twenty-first century the fate of nature has come to depend on the ‘goodwill’ of humans, and to the extent that humans are part of nature the Earth system itself has acquired a moral force.”

Hamilton and Keith debated the geoengineering topic at a joint Harvard–Massachusetts Institute of Technology meeting last fall, with predictably inconclusive results (Figure 2). Nonetheless, the event—and the publication of dueling books—has served to raise the profile of the geoengineering issue. The sparring between those advocating geoengineering research and its opponents has been going on for several years, but it has been rekindled by the publication of the two books and the failure of the governments of the world to agree on ways to curb carbon dioxide emissions.

2. Point counter point. Clive Hamilton (left) of Australia’s Charles Sturt University argued against geoengineering while David Keith of Harvard spoke in favor of it during an October 2013 event. Courtesy: Harvard Public Affairs and Communications

The advocates portray geoengineering as a technological issue. The opponents tend to advance moral objections. In his book, Hamilton argues, “Climate engineering may lend itself to moral corruption. If we are preparing to pursue for self-interested reasons—because we are unwilling to restructure our economies or adjust our lifestyles—then the promotion of geoengineering can provide us with a kind of cover or even self-absolution. But if climate engineering is inferior to cutting emissions (in the sense of being less effective and more risky) then merely by choosing to engineer the climate instead of cutting emissions we succumb to moral failure.”

One of the most aggressive foes of geoengineering has been Joe Romm, a physicist and former Clinton administration Energy Department official, now ensconced at the liberal Washington think tank Center for American Progress. (Hamilton dedicates his book to Romm.) Romm has commented, “Frankly, it would be more literally accurate to rename geoengineering ‘smoke and mirrors,’ as those are two of the most widely discussed measures for managing incoming solar radiation.”

Several years ago, when the geoengineering discussion was just gaining steam, Romm commented, “We’re screwing up the planet with unrestricted greenhouse gas emissions, and the question is, do we want to try to fix that problem by gambling on some other large-scale effort to manipulate the climate—or should we just try to restrict emissions? It’s as if the doctor says you have a disease that can definitely be cured by diet and exercise but you opt for expensive chemotherapy even though the doctor can’t guarantee the results but is pretty certain the side effects would be as bad as the disease.”

Former Vice President Al Gore is also opposed to geoengineering, although he endorses small-scale approaches such as white roofs to reflect incoming solar radiation. But he sneered at the larger-scale plans of technologists such as Keith and Salter. In a conference call with reporters recently, as reported in the Guardian newspaper, Gore said, “The most discussed so-called geoengineering proposals—like putting sulfur dioxide in the atmosphere to reflect incoming sunlight—that’s just insane. Let’s just describe that clearly—it is utterly mad.”

Gore is also cool to what some have termed “soft geoengineering,” a planetwide endeavor to build new nuclear power plants. This is a course proposed by several leading climate scientists, including the prominent climate campaigner and former NASA scientist James Hansen and National Center for Atmospheric Research scientist Tom Wigley.

Gore told the conference call that he’d been a staunch supporter of nuclear power when he was in Congress, but is no longer optimistic about expansion today. “I do believe that it may be possible for scientists and researchers to develop a better and more inherently safer and cheaper form of nuclear reactor, which may yet play a significant role in resolving this crisis. It is not available now.”

Geoengineering advocates acknowledge that nasty side effects could result from spraying sulfur into the air or seawater into clouds. In his Washington Post interview, Keith said, “We can say what the technical risks are. Putting sulfates in the stratosphere can accelerate the depletion of ozone that comes from the chlorine that we’ve already put up there from CFCs. It could change atmospheric circulation in ways that are hard to predict…. The bigger risks have to do with misuse. People often talk about using these technologies to return temperatures to pre-industrial levels. If you did that, that would be a dramatic climate cooling, with bad consequences, like reducing precipitation a lot.”

Keith also takes on the moral question. “Nothing plausible we do to reduce emissions in the next, say, quarter-century is going to materially reduce the risk for real people, especially some of the poorest and most vulnerable on our planet from climate change. So yes, the potential moral hazard is a major problem. But the fact that it’s a major problem is hardly an argument for foregoing a technology that might substantially reduce risk for those living now.”

A Geoengineering Retrospective

“Geoengineering” sounds like a new and somewhat radical, frightening to some, approach to the potential problem of global warming. But using technology, often at large scale, to confront environmental and human issues, is nothing new. Mankind has long moved the environment to suit its needs.

Writing in the Bulletin of the Atomic Scientists, biologist Robert Carlson says, “Humans have a long history of modifying the living systems they rely on. Forests in Europe and North America have been felled for timber and have regrown, while other large tracts of land around the world have been completely cleared for use in agriculture. The animals and plants we humans eat on a regular basis have been selected and bred over millennia to suit the human palate and digestive tract. All these crops and products are shipped and consumed globally to satisfy burgeoning demand.”

In the field of power generation, it’s hard to view big hydro as anything other than terrestrial geoengineering. China’s Three Gorges Dam spanning the Yangtze River is the world’s largest generating station in terms of capacity at 22 GW. As is the case of many large dams (including those in the Tennessee Valley Authority territory and along many of the rivers of the U.S.), Three Gorges has multiple purposes, including power generation, flood control, improved shipping, and providing irrigation water. According to the Carbon Planet website, the dam displaces some 31 million metric tons of coal annually.

The most audacious early approach to geoengineering came in the 1960s and 1970s from the U.S. Atomic Energy Commission’s (AEC’s) Lawrence Livermore National Laboratory. Legendary nuclear physicist Edward Teller (the inspiration for Terry Southern’s satirical movie Dr. Strangelove Or: How I Learned to Stop Worrying and Love the Bomb) concocted and ran a multibillion dollar, multi-decade program, supported by the U.S. Congress, to use hydrogen bombs to rearrange the landscape around the world. He called it “Operation Plowshare.” Teller wanted to create a new port in Alaska, blast out natural gas storage in Pennsylvania, and reroute the Panama Canal. He ultimately failed, as detailed in my 2012 book, Too Dumb to Meter: Follies, Fiascoes, Dead Ends and Duds on the U.S. Road to Atomic Energy.

It’s oddly ironic, but several of the prominent advocates of modern geoengineering, including Jane Long and Ken Caldeira, have close ties to the Livermore lab, although well after Teller exited the direct management of the Department of Energy lab (as successor to the AEC). Teller remained closely associated with Livermore until his death in 2003. Caldeira was a Teller disciple, although Long joined the laboratory staff after Teller died. There is no direct connection to Teller’s aggressive ideas about geoengineering and those of Caldeira or Long, who is a senior advisor to the Environmental Defense Fund.

What’s Next in Geoengineering?

In addition to the “smoke and mirrors” (particulates and clouds) approach to geoengineering, technologists are looking to move beyond preventing sunlight from penetrating the atmosphere and warming the climate. Call it “that giant sucking sound,” or direct carbon capture from the atmosphere. In 2007, flamboyant British entrepreneur Richard Branson put $25 million into a competition for “an environmentally sustainable and economically viable way to remove greenhouse gases from the atmosphere.” The idea is not to capture carbon before it is emitted, but after.

One of the 11 finalists for the “Virgin Earth Challenge,” is Carbon Engineering in Calgary, Alberta, Canada. David Keith is the president of the company. Keith comments, “We hope this technology will make it cheaper to reduce carbon emissions from parts of the transportation infrastructure such as aircraft that are otherwise hard to decarbonize, and we see ourselves competing with other ways to accomplish this goal, such as biofuels.”

The company describes its process as follows: “Our capture technology brings atmospheric air containing CO2 into contact with a chemical solution that naturally absorbs CO2, in a device called a contactor. This solution, now containing the captured CO2, is sent to a regeneration cycle that simultaneously extracts the CO2 while regenerating the original chemical solution, for re-use in the contactor. The extracted CO2 is combined with all the CO2 from the system’s energy use and both are delivered as a high-pressure pipeline-quality product.” (A video of the company’s technology is available at

In their Harvard debate, Hamilton suggested that sucking carbon dioxide out of the atmosphere could attract private investors, which he implied would be a bad idea. He noted that N. Murray Edwards, a Canadian oil sands mogul, recently invested in Keith’s Carbon Engineering. Hamilton argued that private interests would pursue profits and ignore the role of governments in guiding climate policy.

Keith countered that there is nothing sinister about the Edwards investment, which is a matter of “hedging his bets” if fossil fuels prove to be a bad investment. In his book, Keith said he sees “a sharp distinction in the role of private enterprise in solar geoengineering and carbon removal. The development of solar geoengineering should be as public and transparent as possible. The extraordinary global power of these technologies means that they cannot be effectively governed by the local rules appropriate for more conventional technology. I believe that private, for-profit development (and patenting) of the core technologies for solar geoengineering should be strongly discouraged.”

But carbon removal is different, says Keith. “Succeed or fail, the technology we are developing in Carbon Engineering is a contained industrial process with local risks similar to other industrial or mineral processing technology. Our job at Carbon Engineering is to develop a technology but not to decide how or if it’s used.”

The Great Gamble

Is there any last word in this burgeoning dispute? Perhaps it comes from the legendary scientist Freeman Dyson in his 1981 book Disturbing the Universe.

“Science and technology, like all original creations of the human spirit, are unpredictable. If we had a reliable way to label our toys good and bad, it would be easy to regulate technology wisely. But we can rarely see far enough ahead to know which road leads to damnation. Whoever concerns himself with technology, either to push it forward or to stop it, is gambling with human lives.” ■

Kennedy Maize is a POWER contributing editor and blogger.