The Risks of Climate Engineering

by Clive Hamilton (New York Times)

Sarah Jacoby

The Republican Party has long resisted action on climate change, but now that much of the electorate wants something done, it needs to find a way out of the hole it has dug for itself. A committee appointed by the National Research Council may just have handed the party a ladder.

In a two-volume report, the council is recommending that the federal government fund a research program into geoengineering as a response to a warming globe. The study could be a watershed moment because reports from the council, an arm of the National Academies that provides advice on science and technology, are often an impetus for new scientific research programs.

Sometimes known as “Plan B,” geoengineering covers a variety of technologies aimed at deliberate, large-scale intervention in the climate system to counter global warming.

Despairing at global foot-dragging, some climate scientists now believe that a turn to Plan B is inevitable. They see it as inscribed in the logic of the situation. The council’s study begins with the assertion that the “likelihood of eventually considering last-ditch efforts” to address climate destabilization grows every year.

The report is balanced in its assessment of the science. Yet by bringing geoengineering from the fringes of the climate debate into the mainstream, it legitimizes a dangerous approach.

Beneath the identifiable risks is not only a gut reaction to the hubris of it all — the idea that humans could set out to regulate the Earth system, perhaps in perpetuity — but also to what it says about where we are today. As the committee’s chairwoman, Marcia McNutt, told The Associated Press: The public should read this report “and say, ‘This is downright scary.’ And they should say, ‘If this is our Hail Mary, what a scary, scary place we are in.’ ”

Even scarier is the fact that, while most geoengineering boosters see these technologies as a means of buying time for the world to get its act together, others promote them as a substitute for cutting emissions. In 2008, Newt Gingrich, the former House speaker, later Republican presidential candidate and an early backer of geoengineering, said: “Instead of penalizing ordinary Americans, we would have an option to address global warming by rewarding scientific invention,” adding: “Bring on the American ingenuity.”

The report, considerably more cautious, describes geoengineering as one element of a “portfolio of responses” to climate change and examines the prospects of two approaches — removing carbon dioxide from the atmosphere, and enveloping the planet in a layer of sulfate particles to reduce the amount of solar radiation reaching the Earth’s surface.

At the same time, the council makes clear that there is “no substitute for dramatic reductions in the emissions” of greenhouse gases to slow global warming and acidifying oceans.

The lowest-risk strategies for removing carbon dioxide are “currently limited by cost and at present cannot achieve the desired result of removing climatically important amounts,” the report said. On the second approach, the council said that at present it was “opposed to climate-altering deployment” of technologies to reflect radiation back into space.

Still, the council called for research programs to fill the gaps in our knowledge on both approaches, evoking a belief that we can understand enough about how the Earth system operates in order to take control of it.

Expressing interest in geoengineering has been taboo for politicians worried about climate change for fear they would be accused of shirking their responsibility to cut carbon emissions. Yet in some congressional offices, interest in geoengineering is strong. And Congress isn’t the only place where there is interest. Russia in 2013 unsuccessfully sought to insert a pro-geoengineering statement into the latest report of the Intergovernmental Panel on Climate Change.

Early work on geoengineering has given rise to one of the strangest paradoxes in American politics: enthusiasm for geoengineering from some who have attacked the idea of human-caused global warming. The Heartland Institute, infamous for its billboard comparing those who support climate science to the Unabomber, Theodore J. Kaczynski, featured an article in one of its newsletters from 2007 describing geoengineering as a “practical, cost-effective global warming strategy.”

Some scholars associated with conservative think tanks like the Hoover Institution and the Hudson Institute have written optimistically about geoengineering.

Oil companies, too, have dipped their toes into the geoengineering waters with Shell, for instance, having funded research into a scheme to put lime into seawater so it absorbs more carbon dioxide.

With half of Republican voters favoring government action to tackle global warming, any Republican administration would be tempted by the technofix to beat all technofixes.

For some, instead of global warming’s being proof of human failure, engineering the climate would represent the triumph of human ingenuity. While climate change threatens to destabilize the system, geoengineering promises to protect it. If there is such a thing as a right-wing technology, geoengineering is it.

President Obama has been working assiduously to persuade the world that the United States is at last serious about Plan A — winding back its greenhouse gas emissions. The suspicions of much of the world would be reignited if the United States were the first major power to invest heavily in Plan B.

Climate Hacking Is Barking Mad

You can’t fix the Earth with these geoengineering proposals, but you can sure make it worse.

by Raymond T. Pierrehumbert (Slate)

We would be insane to mess with the atmosphere. Photo illustration by Juliana Jimenez Jaramillo. Photo by Frank Bienewald/LightRocket via Getty Images

Some years ago, in the question-and-answer session after a lecture at the American Geophysical Union, I described certain geoengineering proposals as “barking mad.” The remark went rather viral in the geoengineering community. The climate-hacking proposals I was referring to were schemes that attempt to cancel out some of the effects of human-caused global warming by squirting various substances into the atmosphere that would reflect more sunlight back to space. Schemes that were lovingly called “solar radiation management” by geoengineering boosters. Earlier I had referred to the perilous state such schemes would put our Earth into as being analogous to the fate of poor Damocles, cowering under a sword precariously suspended by a single thread.

This week, the National Research Council (NRC) is releasing a report on climate engineering that deals with exactly those proposals I found most terrifying. The report even recommends the creation of a research program addressing these proposals. I am a co-author of this report. Does this mean I’ve had a change of heart?


The nearly two years’ worth of reading and animated discussions that went into this study have convinced me more than ever that the idea of “fixing” the climate by hacking the Earth’s reflection of sunlight is wildly, utterly, howlingly barking mad. In fact, though the report is couched in language more nuanced than what I myself would prefer, there is really nothing in it that is inconsistent with my earlier appraisals.

Even the terminology used in the report signals a palpable change in the framing of the discussion. The actions discussed for the most part are referred to as “climate intervention,” rather than “climate engineering” (or the common but confusing term geoengineering). Engineering is something you do to a system you understand very well, where you can try out new techniques thoroughly at a small scale before staking peoples’ lives on them. Hacking the climate is different—we have only one planet to live on, and can’t afford any big mistakes. Many of the climate “engineering” proposals are akin to turning the world’s whole population into passengers on a largely untested new fleet of hypersonic airplanes.

Most previous literature has referred to schemes to increase the proportion of sunlight reflected back to space as solar radiation management, as if it were something routine and businesslike, along the lines of “inventory management” or “personnel management.” It is far from clear, however, that solar radiation can be managed in any meaningful sense of the word. The NRC report instead uses the more neutral term “albedo modification.” Albedo is the scientific term for the proportion of sunlight reflected back to space. If the Earth had 100 percent albedo, it would reflect all sunlight back to space and be a frozen ice ball some tens of degrees above absolute zero, heated only by the trickle of heat leaking out from its interior. Earth’s current albedo is about 30 percent, with much of the reflection caused by clouds and snow cover. I myself prefer the term “albedo hacking,” but “albedo modification” does pretty well. My colleague and report co-author James Fleming has called such schemes “untested and untestable, and dangerous beyond belief.” (A companion report also discusses less problematic, if currently expensive, schemes for removing carbon dioxide from the atmosphere. Many of those would be well worth doing if they ever became economical.)

The report describes albedo modification frankly as involving large and partly unknown risks. It states outright that albedo modification “should not be deployed” and emphasizes that the main focus in climate protection should continue to be reduction of CO2 emissions. If we continue to let CO2 build up in the atmosphere and attempt to offset the effects by increasingly extreme albedo modification, the report states, that situation is one of “profoundly increasing risk.” This is a far cry from the cartoonish portrayal of albedo modification as the cheap and obvious method of choice in Superfreakonomics or by Newt Gingrich.

Two albedo modification schemes are singled out for detailed scrutiny. The first of these, called stratospheric aerosol modification, works high up in the atmosphere—in the layer known as the stratosphere—and involves injecting substances such as sulfur dioxide that lead to the creation of tiny particles that scatter sunlight back to space. It’s modeled on what happens in the wake of large volcanic eruptions. The second, called marine cloud brightening, works close to the Earth’s surface and involves injection of particles (usually created from salt spray) that either directly reflect sunlight or modify low-level clouds in a way that makes them more reflective. Both techniques have the glaring problem that the albedo-modifying effects disappear within a few weeks to a few years, whereas the climate effects of the CO2 we emit will persist for millennia, even if we ultimately kick the fossil fuel habit. That means that if the CO2 we have emitted at some time heats the Earth to the point where something intolerably bad starts to happen, active albedo modification would need to be continually maintained basically forever. When has humanity ever managed to sustain a concerted complex technological enterprise for centuries, let alone millennia? An awful lot can happen in a thousand years, much of which we have no way to anticipate. The report recognizes that such a millennial commitment would be unprecedented in human history.

The take-home message is that it is not possible to use albedo modification to counteract peak CO2-induced warming without maintaining the climate intervention without interruption for millennia. At least, that’s the case unless we learn how to actively suck CO2 out of the atmosphere. The problem of millennial commitment makes it exceedingly imprudent to count on albedo modification to get and keep us out of a climate emergency. Absent effective CO2-removal techniques, albedo modification cannot be seen as a temporary measure that can give us time to get our act together to eliminate CO2 emissions. And if at any point albedo modification actions are ceased abruptly, the world would be faced with the rapid release of a century or more of pent-up warming. This is why I refer to such a world as “Damocles world.” A lot could happen in a thousand years that might force abrupt termination of albedo modification, but to just mention one possibility: Think of what an attractive target most of the proposed deployment systems (e.g. tethered balloons or fleets of lumbering stratospheric aircraft) would be for terrorists, or for nations who believe rightly or wrongly that they are being harmed by albedo modification.

Temporary deployment scenarios, which are used to delay warming rather than limit its ultimate magnitude, are also considered in the report, which takes no stance on what form of deployment is most likely if the world is ever driven to that stage. I myself think the temporary deployment scenarios are highly implausible, and are mainly shopped by albedo-modification boosters as a less threatening way to get the camel’s nose in the tent. I think that if people realized how little albedo modification can do for climate without taking on a millennial commitment, and that even such modest goals come within reach only when CO2 emissions reductions are so successful you hardly need albedo modification at all, a lot of the enthusiasm for the technology—already feeble outside the small circle of boosters—would evaporate.

Albedo hacking in the face of high CO2 would put the Earth in a state that has no real analogue in all of human history. In fact, the state you create by such an action is somewhat like the state the Earth was in some 250 million years ago during the Permian period, when the sun was dimmer but atmospheric CO2 was higher. A more disturbing comparison involves what would happen if albedo hacking ends abruptly: That would risk warming of a magnitude unseen since the Paleocene-Eocene rapid warming event some 55 million years ago, but at a rate that is probably unprecedented in all of Earth history. The hacking would also transform a substantial amount of direct sunlight into diffuse sunlight, altering the environment for all green plants on land.

More generally, the climate of the Earth is determined by a struggle of two different parts of our planetary energy budget. One part is heat energy loss to space; CO2 affects that. The other part is the amount of sunlight absorbed; albedo modification affects that, but the consequences of turning this dial are not at all equivalent to dialing back CO2 to pre-industrial values. This dial can probably be used to reduce global mean temperature (though with uncertain precision), but there is much more to climate than that. The global cooling that could possibly be achieved comes at the cost of changes in rainfall patterns, winds, and regional temperature. With the current state of climate models, we have only very limited confidence in our ability to predict the outcomes, and even more limited ability to model the actual albedo change resulting from the complex chain of events due to an actual climate-intervention action. What’s more, our current ability to even monitor what we actually did to the sky leaves a lot to be desired. And albedo modification does little or nothing to ameliorate the acidification of the oceans caused by CO2 emissions. All that is acknowledged frankly in the report.

In other words, albedo modification addresses (albeit imperfectly) the symptoms but not the root causes of CO2-induced global warming. As a possible response to such criticisms, Oxford’s Steve Rayner has mused that “Band-Aids are useful when you are healing.” However, Band-Aids are not all that useful if you really needed penicillin instead, and the wound festers until you die. Albedo modification is not like a bandage that promotes healing, but more like taking painkillers when you really need surgery for cancer.

It could be argued with some justification that if we do not severely restrict CO2 emissions, future generations will not have the choice to pursue a climate that is roughly similar to conditions before the Industrial Revolution. The relevant comparison, according to this argument, isn’t between the albedo-modified state and the pre-industrial state, but rather between a hot, high-CO2 state and a generally cooler (on average) albedo-modified state. That’s the “lesser of two evils” argument, and the associated justification for research is called “arming the future.” It is not hard to imagine a future world where albedo modification becomes a matter of survival (at least until something happens to force an abrupt termination). Unrestrained CO2 emissions could render large parts of the Earth uninhabitable for large mammals (including us) outdoors, and it is not hard to imagine a panicked rush to embrace albedo modification in such a situation. The problem with the arming the future argument, as pointed out by philosopher Stephen Gardiner, is that the lesser of two evils is still an evil, and the greatest moral culpability of all falls on those who, as in the case of the tragic Sophie’s choice, put somebody in the position where they have no alternative but to make an evil choice. That is precisely what we would be doing to future generations if we continue to shirk our responsibility for restraining CO2 emissions.

The moral culpability issue is compounded by the fact that even a limited deployment of albedo modification, by removing some of the more palpable symptoms of climate disruption, would almost certainly remove some of the incentives for doing the hard things needed to decarbonize the economy. To the extent that research brings such deployments closer to reality, even that research can incur risks that move us farther along the spectrum of moral culpability.

Now, about those research recommendations: If albedo modification is such a terrible idea, why do research on it at all? Indeed in his book, Mike Hulme considers the technology ungovernable and argues that if a technology is basically ungovernable at the level of deployment, we shouldn’t be doing research that could bring it into being. The new NRC report’s specific research recommendations are actually quite cautious, focusing primarily on things that contribute to a better understanding of climate in general, in addition to being necessary prerequisites for a better-informed judgment of the risks of albedo modification. That includes research priorities such as a better understanding of clouds, better understanding of tropical precipitation changes, and better monitoring of the Earth’s energy budget (including those things needed to understand the response of climate to volcanic eruptions).

Going beyond fairly uncontroversial research of this type engages value judgments well outside of what a group of 16 scientists such as ours is equipped to decide, and goes well beyond the boundaries of scientific judgment itself. The report recommends, of necessity rather diffusely, the initiation of a “serious deliberative process” which would ultimately determine the nature of the research program and how it would be governed. I intend to be quite vocal in this process, if it ever gets underway. Some others on the committee no doubt have different ideas about what the outcome of the process should be. For example, a recent Nature opinion piece unconnected with the NRC report itself but co-authored by Granger Morgan (another of the NRC panel members) argues that research should initially proceed without any governance, at the discretion of the scientists involved. I guess Granger and I will have to duke that out as part of the “serious deliberative process” recommended by the NRC.

The real consequences of NRC recommendations for research would only be settled as part of the serious deliberative process the report recommends, and that is where the hard work and hard decisions will take place. It’s not at all clear how this is going to happen. In the United States, can we actually have a reality-based, serious deliberative process about anything anymore? Can a serious deliberative process about climate change materially involve a Congress that cannot even muster a Senate majority to agree that humans can and are changing the climate? With the present state of leadership (and not just in the United States), developing albedo-modification technology would be like giving a loaded gun to a child. (OK, in the U.S. some people actually do that; it doesn’t mean it’s a good idea.)

So yes, albedo hacking is still barking mad, but people are often driven to do barking mad things out of desperation, and we are heading to the breaking point now with our continued fossil fuel binge. But if it comes to albedo hacking, the result won’t be pretty. It won’t be some benign “Plan B,” but more like the constant fear of thermonuclear holocaust I grew up with during the Cold War. It will be the end of blue skies and crystal-clear starry nights, and the beginning of nightly blood-red sunsets. These are not the most serious consequences of albedo hacking, but they will serve as nightly visible proof of our moral failure. And there will be no exit, not for thousands of years (unless we figure out a way to suck CO2 out of the atmosphere). If the serious deliberative process counseled by the NRC report makes people stop and think about just how terrifying that world would be, perhaps the thought of a world with less reliance on fossil fuels would start to seem a lot less scary.

Plan B? What Happened to Plan A?

Why we shouldn’t fund geoengineering experimentation, and what we still need to learn about the climate

by Pat Mooney (ETC Group)

The US National Academy of Sciences has released two reports on geoengineering that recommend investments in solar radiation management (SRM) and carbon capture and storage (CCS). Geoengineering has become known as the US government’s “Plan B” response to climate change. Geoengineering proponents have recently pushed for government funding of geoengineering research in Nature and the Washington Post.

At first glance, this seems prudent: of course we should have more information about all of the options. Most geoengineering backers insist that these are only extreme measures of last resort. SRM (now rebranded as “albedo management” by the NAS report) which proposes blowing sulfate aerosols into the stratosphere to block sunlight and lower global temperatures or CCS, which proposes to stuff billions of tonnes of CO2 into defunct mines and oil wells, are Plan B: only to be considered if governments can’t agree on emission targets in Paris later this year. Is geoengineering deplorable or deployable? We won’t know, backers argue, unless we do the research.

Plan B?

Saying we need more information sounds reasonable, but geoengineering research that involves experimentation and builds actual hardware is a clear and present danger to the climate for two reasons. If the US or other powerful governments accept geoengineering as a plausible “Plan B,” Plan A will evaporate faster than Congressional bipartisanship. The fossil fuel industry is desperate to protect between $20 and $28 trillion in booked assets that can only be extracted if the corporations are allowed to overshoot GHG-emissions. The theoretical assumption that carbon capture and storage will eventually let them recapture CO2 from the atmosphere and bury it in the earth or ocean provides the fossil fuel industry with the best way to avoid popping the “carbon bubble” other than outright climate denial. Spraying sulfates in the stratosphere can – theoretically – lower temperatures until carbon capture and storage techniques are viable. In other words, geoengineering research is becoming the only tool the fossil fuel industry has left to undermine the political and corporate will to lower actual emissions now.

Geoengineering could justify continued emissions, but it may also do direct damage to the climate. The two NAS reports are quiet about budgets and don’t define the scale of field studies. Most scientists concur that geoengineering is extremely risky, but also say that only very large field trials will yield useful data. Experimentation, in other words, equals hardware development and effective deployment. We already have examples: between 1993 and 2009, 11 governments conducted a dozen geoengineering experiments in international waters to see if spreading iron particles on the surface of the ocean could lead to the sequestering of carbon dioxide on the ocean floor. The first experiments dumped iron into 50-60 km² of ocean. When that didn’t work, they increased the surface area six-fold until the final 2009 dump was 300 km². It still failed. The geoengineers wanted bigger experiments, but three different UN conferences intervened and have effectively banned ocean fertilization. Sagely, the NAS report now concludes that ocean fertilization “is an immature technology whose high costs and technical and environmental risks currently outweigh the benefits.”

NAS also talks about the need for governance but only in the context of the United States. Stratospheric aerosol spraying can be undertaken by one country or a “Coalition of the Willing,” even though the impact will be global. For this reason, the United Nations must be in charge.

What about Plan A?

There is much that scientists don’t know about planetary systems. The acknowledged gaps in Plan A research have widened from a crevice to a chasm to a canyon. It would be extraordinarily foolhardy for policymakers to advance Plan B before Plan A’s research issues are addressed.

It is difficult, for example, to establish Plan A emission targets (or, for that matter, Plan B’s levels of stratospheric aerosol spraying) when governments don’t disclose their current emissions. China underreported its annual GHG emissions by about 20%, while the USA’s recent emission reductions aren’t quite what they’re fracked up to be. America cut back its emissions to 1992 levels because fracking lowered the demand for coal – but the coal was still burned overseas. The UK’s 14% reductions (between 1990 and 2008) in greenhouse gas emissions were erased by its 20% increase in emissions from outsourced manufacturing. With the breakup of the Soviet Union, Russian emissions dropped 10 – 14% but only because farmland was temporarily abandoned.

How can we pursue “climate interventions” and call them scientific if governments don’t get the data right?

Governments have also had difficulties keeping track of their biomass, with implications for Plan B’s carbon capture and storage strategies. According to a UNEP report, up to 30% of all timber exports are mafia-controlled and 90% of tropical deforestation is due to illegal trade – making biomass calculations problematic. Meanwhile, India overestimated its forest cover by about 10%.

Australia, Canada, Japan and New Zealand have all flip-flopped on their emission commitments while the UK has cut back its renewable energy support. The EU’s carbon credit scheme is a laughingstock. This makes Plan A’s emission goals – or the levels of Plan B’s stratospheric aerosol interventions – subject to unexpected and dangerous changes.

Plan A and Plan B both need cutting-edge monitoring of planetary systems. However, by 2020, the number of civilian US climate monitoring satellites could drop from 23 to 6 and the number of monitoring instruments from 90 to 20. Monitoring is weakest over the Indian subcontinent and apparently deteriorating throughout the tropics. In 2014, for example, scientists discovered that an important swath of the Brazilian Amazon has been completely missed by satellites. The Economist called this “willful blindness.”

Recently, science has uncovered a vast deep-ocean “river”, a bacterial prairie the size of Greece beneath the Humboldt current, and reconsidered the impact of sulphates on cloud formation in polar regions that could significantly alter Plan B proposals for carbon sequestration or solar radiation management.

Money is indeed needed for climate change research. Governments should pony up and scientists should get to work. But the NAS needs to flatly condemn the deployment or hardware testing of dangerous technologies that have consequences for the whole planet.”

NAS support for geoengineering research creates a political space that could lead multinational oil companies and their governments off the hook. Precisely at the moment when climate denial is losing steam, it’s crucial to prevent it from being replaced with unicorn-like fantasies of magical technologies that allow the status quo to continue.

Pat Mooney is the Executive Director of ETC Group.