The Geoengineering Option

The Geoengineering Option

A Last Resort Against Global Warming?

David G. Victor, M. Granger Morgan, Jay Apt, John Steinbruner, and Katharine Ricke

m a r c h / a p r i l 2oo9

Volume 88 Number 2

The contents of Foreign Affairs are copyrighted.2009 Council on Foreign Relations, Inc. All rights reserved. Reproduction and distribution of this material is permitted only with the express written consent of Foreign Affairs. Visit www.foreignaffairs.org/permissions for more information.

Each year, the eects of climate change are coming into sharperfocus. Barely a month goes by without some fresh bad news: ice sheetsand glaciers are melting faster than expected, sea levels are rising morerapidly than ever in recorded history, plants are blooming earlier inthe spring, water supplies and habitats are in danger, birds are beingforced to nd new migratory patterns.

The odds that the global climate will reach a dangerous tippingpoint are increasing. Over the course of the twenty-rst century, keyocean currents, such as the Gulf Stream, could shift radically, andthawing permafrost could release huge amounts of additional green-house gases into the atmosphere. Such scenarios, although still remote,would dramatically accelerate and compound the consequences ofglobal warming. Scientists are taking these doomsday scenarios seriouslybecause the steady accumulation of warming gases in the atmosphere

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A Last Resort Against Global Warming?

David G. Victor, M. Granger Morgan, Jay Apt,John Steinbruner, and Katharine Ricke

David G . Victor is a Professor at Stanford Law School, Director ofStanfords Program on Energy and Sustainable Development, and an AdjunctSenior Fellow at the Council on Foreign Relations. M . GrangerMorgan is Head of Carnegie Mellon Universitys Department ofEngineering and Public Policy and Director of the Climate DecisionMaking Center. Jay Apt is Professor of Engineering and Public Policyat Carnegie Mellon University. John Steinbruner is Professor ofPublic Policy and Director of the Center for International and SecurityStudies at the University of Maryland. Katharine Ricke is a doctoralstudent at Carnegie Mellon University. Additional materials are availableonline at www.cfr.org/geoengineering.

is forcing change in the climate system at rates so rapid that the out-comes are extremely dicult to predict.

Eliminating all the risks of climate change is impossible becausecarbon dioxide emissions, the chief human contribution to globalwarming, are unlike conventional air pollutants, which stay in the atmos-phere for only hours or days. Once carbon dioxide enters the atmosphere,much of it remains for over a hundred years. Emissions from anywhereon the planet contribute to the global problem, and once headed inthe wrong direction, the climate system is slow to respond to attemptsat reversal. As with a bathtub that has a large faucet and a small drain,the only practical way to lower the level is by dramatically cutting theinow. Holding global warming steady at its current rate would require aworldwide 6080 percent cut in emissions, and it would still take decadesfor the atmospheric concentration of carbon dioxide to stabilize.

Most human emissions of carbon dioxide come from burning fossilfuels, and most governments have been reluctant to force the radicalchanges necessary to reduce those emissions. Economic growth tendsto trump vague and elusive global aspirations. The United Stateshas yet to impose even a cap on its emissions, let alone a reduction.The European Union has adopted an emissions-trading scheme that,although promising in theory, has not yet had much real eect becausecarbon prices are still too low to cause any signicant change in behavior.Even Norway, which in 1991 became one of the rst nations to imposea sti tax on emissions, has seen a net increase in its carbon dioxideemissions. Japan, too, has professed its commitment to taming globalwarming. Nevertheless, Tokyo is struggling to square the need foreconomic growth with continued dependence on an energy systempowered mainly by conventional fossil fuels. And Chinas emissionsrecently surpassed those of the United States, thanks to coal-fueledindustrialization and a staggering pace of economic growth. Theglobal economic crisis is stanching emissions a bit, but it will not comeclose to shutting o the faucet.

The worlds slow progress in cutting carbon dioxide emissions andthe looming danger that the climate could take a sudden turn for theworse require policymakers to take a closer look at emergency strategiesfor curbing the eects of global warming. These strategies, often calledgeoengineering, envision deploying systems on a planetary scale, such


foreign affairs . March /April 2009 [65 ]

as launching reective particles into the atmosphere or positioningsunshades to cool the earth. These strategies could cool the planet,but they would not stop the buildup of carbon dioxide or lessen all itsharmful impacts. For this reason, geoengineering has been widelyshunned by those committed to reducing emissions.

Serious research on geoengineering is still in its infancy, and it hasnot received the attention it deserves from politicians. The timehas come to take it seriously. Geoengineering could provide a usefuldefense for the planetan emergency shield that could be deployedif surprisingly nasty climatic shifts put vital ecosystems and billions ofpeople at risk. Actually raising the shield, however, would be a politicalchoice. One nations emergency can be anothers opportunity, and itis unlikely that all countries will have similar assessments of howto balance the ills of unchecked climate change with the risk that geo-engineering could do more harm than good. Governments shouldimmediately begin to undertake serious research on geoengineeringand help create international norms governing its use.

the rainmakersGeoengineering is not a new idea. In 1965, when President LyndonJohnson received the rst-ever U.S. presidential brieng on the dangersof climate change, the only remedy prescribed to counter the eectsof global warming was geoengineering. That advice reected thescientic culture of the time, which imagined that engineering couldx almost any problem.

By the late 1940s, both the United States and the Soviet Union hadbegun exploring strategies for modifying the weather to gain bat-tleeld advantage. Many schemes focused on seeding clouds withsubstances that would coax them to drop more rain. Despite oeringno clear advantage to the military, weather makers were routinelyemployed (rarely with much eect) to squeeze more rain from cloudsfor thirsty crops. Starting in 1962, U.S. government researchers forProject Stormfury tried to make tropical hurricanes less intensethrough cloud seeding, but with no clear success. Military experts alsodreamed of using nuclear explosions and other interventions to createa more advantageous climate. These applications were frightening

Victor, Morgan, Apt, Steinbruner, and Ricke

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enough that in 1976 the UnitedNations adopted the Conventionon the Prohibition of Militaryor Any Other Hostile Use ofEnvironmental ModicationTechniques to bar such projects.By the 1970s, after a string offailures, the idea of weathermodication for war and farm-ing had largely faded away.

Todays proposals for geo-engineering are more likely tohave an impact because the inter-ventions needed for global-scalegeoengineering are much less subtlethan those that sought to inuencelocal weather patterns. The earthsclimate is largely driven by the nebalance between the light energywith which the sun bathes the earthand the heat that the earth radiates backto space. On average, about 70 percent of theearths incoming sunlight is absorbed by theatmosphere and the planets surface; the remainder is reected backinto space. Increasing the reectivity of the planet (known as thealbedo) by about one percentage point could have an eect on the cli-mate system large enough to oset the gross increase in warming thatis likely over the next century as a result of a doubling of the amountof carbon dioxide in the atmosphere. Making such tweaks is muchmore straightforward than causing rain or fog at a particular locationin the ways that the weather makers of the late 1940s and 1950sdreamed of doing.

In fact, every few decades, volcanoes validate the theory that it ispossible to engineer the climate. When Mount Pinatubo, in the Philip-pines, erupted in 1991, it ejected plumes of sulfate and other ne particlesinto the atmosphere, which reected a bit more sunlight and cooledthe planet by about 0.5 degrees Celsius over the course of a year. Larger


eruptions, such as the 1883 eruption of Krakatau, in Indonesia, havecaused even greater cooling that lasted longer. Unlike eorts to controlemissions of greenhouse gases, which will take many years to yield anoticeable eect, volcano-like strategies for cooling the planet wouldwork relatively promptly.

Another lesson from volcanoes is that a geoengineering systemwould require frequent maintenance, since most particles lofted intothe stratosphere would disappear after a year or two. Once a geoengi-neering project were under way, there would be strong incentivesto continue it, since failure to keep the shield in place could allowparticularly harmful changes in the earths climate, such as warmingso speedy that ecosystems would collapse because they had no timeto adjust. By carefully measuring the climatic eects of the next majorvolcanic eruption with satellites and aircraft, geoengineers coulddesign a number of climate-cooling technologies.

albedo enhancersToday, the term geoengineering refers to a variety of strategiesdesigned to cool the climate. Some, for example, would slowly removecarbon dioxide from the atmosphere, either by manipulating thebiosphere (such as by fertilizing the ocean with nutrients that wouldallow plankton to grow faster and thus absorb more carbon) or bydirectly scrubbing the air with devices that resemble big coolingtowers. However, from what is known today, increasing the earthsalbedo oers the most promising method for rapidly cooling the planet.

Most schemes that would alter the earths albedo envision puttingreective particles into the upper atmosphere, much as volcanoes doalready. Such schemes oer quick impacts with relatively little eort.For example, just one kilogram of sulfur well placed in the stratospherewould roughly oset the warming eect of several hundred thousandkilograms of carbon dioxide. Other schemes include seeding brightreective clouds by blowing seawater or other substances into thelower atmosphere. Substantial reductions of global warming are alsopossible to achieve by converting dark places that absorb lots of sunlightto lighter shadesfor example, by replacing dark forests with morereective grasslands. (Engineered plants might be designed for the task.)



More ambitious projects could include launching a huge cloud of thinrefracting discs into a special space orbit that parks the discs betweenthe sun and the earth in order to bend just a bit of sunlight away beforeit hits the planet.

So far, launching reective materials into the upper stratosphereseems to be the easiest and most cost-eective option. This couldbe accomplished by using high-ying aircraft, naval guns, or giantballoons. The appropriate materials could include sulfate aerosols(which would be created by releasing sulfur dioxide gas), aluminumoxide dust, or even self-levitating and self-orienting designer particles engineered tomigrate to the Polar Regions and remain inplace for long periods. If it can be done,concentrating sunshades over the poles wouldbe a particularly interesting option, sincethose latitudes appear to be the most sensitiveto global warming. Most cost estimates forsuch geoengineering strategies are preliminary and unreliable. How-ever, there is general agreement that the strategies are cheap; the totalexpense of the most cost-eective options would amount to perhapsas little as a few billion dollars, just one percent (or less) of the costof dramatically cutting emissions.

Cooling the planet through geoengineering will not, however,x all of the problems related to climate change. Osetting warmingby reecting more sunlight back into space will not stop the risingconcentration of carbon dioxide in the atmosphere. Sooner or later,much of that carbon dioxide ends up in the oceans, where it formscarbonic acid. Ocean acidication is a catastrophe for marine ecosys-tems, for the 100 million people who depend on coral reefs for theirlivelihoods, and for the many more who depend on them for coastalprotection from storms and for biological support of the greater oceanfood web. Over the last century, the oceans have become markedlymore acidic, and current projections suggest that without a seriouseort to control emissions, the concentration of carbon dioxide willbe so high by the end of the century that many organisms that makeshells will disappear and most coral reef ecosystems will collapse,devastating the marine shing industry. Recent studies have also


foreign affairs . March /April 2009 [69]

Every few decades,

volcanoes validate the

theory that it is possible

to engineer the climate.

suggested that ocean acidication will increase the size and depth ofdead zones, areas of the sea that are so oxygen depleted that largermarine life, such as squid, are unable to breathe properly.

Altering the albedo of the earth would also aect atmosphericcirculation, rainfall, and other aspects of the hydrologic cycle. In thesix to 18 months following the eruption of Mount Pinatubo, rainfalland river ows dropped, particularly in the tropics. Understandingthese dangers better would help convince government leaders in rainfall-sensitive regions, such as parts of China and India (along with NorthAfrica, the Middle East, and the desert regions of the southwesternUnited States), not to prematurely deploy poorly designed geoengi-neering schemes that could wreak havoc on agricultural productivity.Indeed, some climate models already suggest that negative outcomesdecreased precipitation over land (especially in the tropics) and increasedprecipitation over the oceanswould accompany a geoengineeringscheme that sought to lower average temperatures by raising the planetsalbedo. Such changes couldincrease the risk of majordroughts in some regionsand have a major impact onagriculture and the supply offresh water. Complementarypoliciessuch as investingin better water-managementschemesmay be needed.

The highly uncertainbut possibly disastrous sideeects of geoengineeringinterventions are dicultto compare to the dangersof unchecked global climatechange. Chances are that ifcountries begin deployinggeoengineering systems, itwill be because calamitousclimate change is near athand. Yet the assignment



of blame after a geoengi-neering disaster would bevery dierent from the

current debates over who isresponsible for climate change,which is the result of centuries

of accumulated emissions fromactivities across the world. By con-

trast, the side eects of geoengineeringprojects could be readily pinned on the

geoengineers themselves. That is onereason why nations must begin building

useful international norms to govern geo-engineering in order to assess its dangers

and decide when to act in the event of animpending climatic disaster.

lone rangersAn effective foreign policy strategy for man-

aging geoengineering is dicult to formulate becausethe technology involved turns the normal debate over climate changeon its head. The best way to reduce the danger of global warming is,of course, to cut emissions of carbon dioxide and other greenhousegases. But success in that venture will require all the major emittingcountries, with their divergent interests, to cooperate for severaldecades in a sustained eort to develop and deploy completely newenergy systems with much lower emissions. Incentives to defect andavoid the high cost of emissions controls will be strong.

By contrast, geoengineering is an option at the disposal of anyreasonably advanced nation. A single country could deploy geo-engineering systems from its own territory without consulting therest of the planet. Geoengineers keen to alter their own countrysclimate might not assess or even care about the dangers their actionscould create for climates, ecosystems, and economies elsewhere. Aunilateral geoengineering project could impose costs on other countries,such as changes in precipitation patterns and river ows or adverse


impacts on agriculture, marine shing, and tourism. And merelyknowing that geoengineering exists as an option may take the pressureo governments to implement the policies needed to cut emissions.

At some point in the near future, it is conceivable that a nationthat has not done enough to confront climate change will conclude

that global warming has become so harm-ful to its interests that it should unilaterallyengage in geoengineering. Although it ishardly wise to mess with a poorly understoodglobal climate system using instrumentswhose eects are also unknown, politiciansmust take geoengineering seriously becauseit is cheap, easy, and takes only one govern-

ment with sucient hubris or desperation to set it in motion. Exceptin the most dire climatic emergency, universal agreement on thebest approach is highly unlikely. Unilateral action would create acrisis of legitimacy that could make it especially dicult to managegeoengineering schemes once they are under way.

Although governments are the most likely actors, some geoengi-neering options are cheap enough to be deployed by wealthy andcapable individuals or corporations. Although it may sound like thestu of a future James Bond movie, private-sector geoengineersmight very well attempt to deploy aordable geoengineering schemeson their own. And even if governments manage to keep freelancegeoengineers in check, the private sector could emerge as a potentforce by becoming an interest group that pushes for deployment ordrives the direction of geoengineering research and assessment.Already, private companies are running experiments on oceanfertilization in the hope of sequestering carbon dioxide and earningcredits that they could trade in carbon markets. Private developersof technology for albedo modication could obstruct an open andtransparent research environment as they jockey for position inthe potentially lucrative market for testing and deploying geo-engineering systems. To prevent such scenarios and to establishthe rules that should govern the use of geoengineering technologyfor the good of the entire planet, a cooperative, international researchagenda is vital.


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Fiddling with the climate

to x the climate strikes

most people as a

shockingly bad idea.

from science fiction to factsDespite years of speculation and vague talk, peer-reviewed researchon geoengineering is remarkably scarce. Nearly the entire communityof geoengineering scientists could t comfortably in a single universityseminar room, and the entire scientic literature on the subject couldbe read during the course of a transatlantic ight. Geoengineeringcontinues to be considered a fringe topic.

Many scientists have been reluctant to raise the issue for fear thatit might create a moral hazard: encouraging governments to deploygeoengineering rather than invest in cutting emissions. Indeed, geo-engineering ventures will be viewed with particular suspicion if thenations funding geoengineering research are not also investing indramatically reducing their emissions of carbon dioxide and othergreenhouse gases. Many scientists also rightly fear that grants forgeoengineering research would be subtracted from the existing fundsfor urgently needed climate-science research and carbon-abatementtechnologies. But there is a pressing need for a better understandingof geoengineering, rooted in theoretical studies and empirical eldmeasurements. The subject also requires the talents of engineers,few of whom have joined the small group of scientists studyingthese techniques.

The scientic academies in the leading industrialized and emergingcountrieswhich often control the purse strings for major researchgrantsmust orchestrate a serious and transparent internationalresearch eort funded by their governments. Although some work isalready under way, a more comprehensive understanding of geoengineer-ing options and of risk-assessment procedures would make countries lesstrigger-happy and more inclined to consider deploying geoengineeringsystems in concert rather than on their own. (The International Councilfor Science, which has a long and successful history of coordinatingscientic assessments of technical topics, could also lend a helping hand.)Eventually, a dedicated international entity overseen by the leadingacademies, provided with a large budget, and suused with the normsof transparency and peer review will be necessary.

In time, international institutions such as the IntergovernmentalPanel on Climate Change could be expected to synthesize the ndings



from the published research. The ipcc, which shared the Nobel PeacePrize in 2007 for its pivotal role in building a consensus around climatescience, has not considered geoengineering so far because the topic ispolitically radioactive and there is a dearth of peer-reviewed researchon it. The ipccs fth assessment report on climate change, which isbeing planned right now, should promise to take a closer look at geo-engineering. Attention from the ipcc and the worlds major scienticacademies would help encourage new research.

A broad and solid foundation of research would help on threefronts. First, it would transform the discussion about geoengineeringfrom an abstract debate into one focused on real risk assessment. Second,

a research program that was backed by theworlds top scientic academies could securefunding and political cover for essential butcontroversial experiments. (Field trials ofengineered aerosols, for example, could sparkprotests comparable to those that accompaniedtrials of genetically modied crops.) Suchexperiments will be seen as more acceptableif they are designed and overseen by theworlds leading scientists and evaluated in a

fully transparent fashion. Third, and what is crucial, a better under-standing of the dangers of geoengineering would help nations craftthe norms that should govern the testing and possible deploymentof newly developed technologies. Scientists could be inuential increating these norms, just as nuclear scientists framed the optionson nuclear testing and inuenced pivotal governments during theCold War.

If countries were actually to contemplate the deployment of geo-engineering technologies, there would inevitably be questions raisedabout what triggers would compel the use of these systems. Today,nobody knows which climatic triggers are most important for geo-engineering because research on the harmful eects of climate changehas not been coupled tightly enough with research on whether andhow geoengineering might oset those eects.

Although the international scientic community should take the leadin developing a research agenda, social scientists, international lawyers,


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The option of

geoengineering exists.

It would be dangerous

for scientists and

policymakers to

ignore it.

and foreign policy experts will also have to play a role. Eventually,there will have to be international laws to ensure that globally credibleand legitimate rules govern the deployment of geoengineering systems.But eective legal norms cannot be imperiously declared. They mustbe carefully developed by informed consensus in order to avoid encour-aging the rogue forms of geoengineering they are intended to prevent.

Those who worry that such research will cause governments toabandon their eorts to control emissions, including much of the envi-ronmental community, are prone to seek a categorical prohibitionagainst geoengineering. But a taboo would interfere with much-neededscientic research on an option that might be better for humanity andthe worlds ecosystems than allowing unchecked climate change orreckless unilateral geoengineering. Formal prohibition is unlikelyto stop determined rogues, but a smart and scientically sanctionedresearch program could gather data essential to understanding the risksof geoengineering strategies and to establishing responsible criteriafor their testing and deployment.

brave new worldFiddling with the climate to x the climate strikes most peopleas a shockingly bad idea. Many worry that research on geoengineeringwill make governments less willing to regulate emissions. It is morelikely, however, that serious study will reveal the many dangerous sideeects of geoengineering, exposing it as a true option of last resort.But because the option exists, and might be used, it would be dangerousfor scientists and policymakers to ignore it. Assessing and managingthe risks of geoengineering may not require radically dierent approachesfrom those used for other seemingly risky endeavors, such as geneticengineering (research on which was paused in the 1970s as scientistsworked out useful regulatory systems), the construction and use ofhigh-energy particle accelerators (which a few physicists suggestcould create black holes that might swallow the earth), and thedevelopment of nano technology (which some worry could unleashself-replicating nanomachines that could reduce the world to graygoo). The option of eliminating risk altogether does not exist.Countries have kept smallpox samples on hand, along with samples



of many other diseases, such as the Ebola and Marburg viruses, despitethe danger of their inadvertent release. All of these are potentiallydangerous endeavors that governments, with scientic support,have been able to manage for the greater good.

Humans have already engaged in a dangerous geophysical ex-periment by pumping massive amounts of carbon dioxide and othergreenhouse gases into the atmosphere. The best and safest strategyfor reversing climate change is to halt this buildup of greenhousegases, but this solution will take time, and it involves myriad practicaland political diculties. Meanwhile, the dangers are mounting. Ina few decades, the option of geoengineering could look less uglyfor some countries than unchecked changes in the climate. Nor isit impossible that later in the century the planet will experience aclimatic disaster that puts ecosystems and human prosperity atrisk. It is time to take geoengineering out of the closetto bettercontrol the risk of unilateral action and also to know the costs andconsequences of its use so that the nations of the world can collectivelydecide whether to raise the shield if they think the planet needs it.



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The Geoengineering Option