| 摘要 | In December 2009, the UN climate summit in Copenhagen ended with little to show for the event but a non-binding agreement to keep on trying. That was no surprise: After all, 20 years of prior talks had yielded no discernable change in emissions. What is surprising, though, is that so many analysts continue to view climate policy as a thing apart from global power politics. Indeed, one needed really big blinders to miss the fact that the growing rivalry between the United States and China was central to the (in)action at Copenhagen.
Adding geopolitics alters the picture considerably. The most direct (and, to some, the most desirable) means of slowing climate change–containing greenhouse gas emissions–appears far less practical, while a new approach called climate engineering emerges as a potential winner.
To date, the debate about CE has focused on the science. I would argue, though, that the more central issue, is political not technical. And while climate engineering faces a variety of political hurdles, they are quite different than those facing emissions containment initiatives–and may prove less challenging.
Climate Policy and Power
Lloyd Gruber, a political economist at the London School of Economics, offers a taxonomy of power that is a good starting point for thinking about the politics of climate policy. First, Gruber observes, nations can have “go-it-alone power”–that is, they can act without other states’ consent. For instance, in 1988, the United States and Canada had go-it-alone power to create a free trade zone. Other countries might have preferred that they not act without multilateral approval, but they had little choice in the matter; indeed, some ultimately chose to join the agreement rather than face isolation.
Second, states may be able to block actions they oppose–that is, they may have “hold-up power.” Technology can determine where hold-up power exists. For example, nations have little power to stop satellite-based remote sensing, but plenty to block TV signals.
Third is the power to coerce with sanctions or force. Coercion, though, is often costly. It is most likely to work at an acceptable cost to the coercer when strong states impose their will on weak ones. It can take several forms short of military action. States with market power over some vital good or service may threaten to withhold it. But the threat to limit access to a large rich market is often even more potent. Indeed, the relative size of two states’ domestic markets is a key metric of their relative power to use economic coercion.
Power would not matter so much in climate policy if states’ interests were harmonious. In fact, they diverge. India, with a relatively warm climate, will suffer more from further warming than will Russia, which may actually benefit from longer growing seasons and the availability of new opportunities for oil and gas drilling in the Arctic Sea.
The level of a country’s economic development can also matter, and in several (sometimes conflicting) ways. On the one hand, a more advanced economy is likely to depend less on weather-sensitive agriculture and forestry, and it will command more of the wealth needed to cope with harm from climate change once it occurs. On the other hand, affluence may strengthen environmental values that raise public awareness of climate change and spark demands to halt it.
GHG emissions have the same impact on climate whatever their point of origin, and halting the rise of GHG levels in the atmosphere would require limiting discharges to quite low levels. Thus to be effective, stringent GHG controls would have to cover all major regions of the globe.
That task demands a global regime. One, in fact, already exists: the United Nations Framework Convention on Climate Change. The UNFCCC’s widely recognized fecklessness is, in some ways, less of a puzzle than the fact that some other global regimes–for example, the World Trade Organization–work pretty well. A regime that tackles a big international problem might, to be sure, hope to offer big benefits, but it is also subject to the challenge posed by the need for collective action. In such cases, each state will be tempted to try to reap the benefits of others’ adherence to the rules while seeking to shirk its own obligations. Yet, in the anarchic milieu of world politics, no authority exists to impose and enforce those rules. How, then, are successful regimes formed and maintained?
In the modern era, the answer has largely been that the most powerful state in the global system coerced/ cajoled others into joining and obeying. Britain played this role first; then, after World War II, the United States took up the mantel. Because of the large size of their economies, these “hegemons” often had stronger motives than other states did to bear the costs of organizing regimes; moreover, their power gave them the means of enforcing membership and adherence to the rules. Even so, the role could be vexatious.
Barriers to Emissions Control
The task of building an effective GHG control regime is especially daunting. Count the ways:
— Contrary to the conventional wisdom, if the future gains from curbing climate change are discounted at the interest rates used to discount the gains from other sorts of investments, the net benefits from even the most cost-effective GHG controls are likely to be relatively modest. One recent estimate pegged their present value at slightly more than $3 trillion–not a very big number in a global economy with annual output exceeding $60 trillion. To be sure, some analysts reject a formulation in which the welfare of our great, great grandchildren carries virtually no weight. But, while academic debate continues on the issue, the world goes on discounting the future just as it always has.
— Reconciling the disparities in national preferences/interests over climate is bound to involve complex bargaining. In principle, those countries most anxious to rein in emissions (at the moment, the European Union) could offer side payments to those that are opposed or indifferent (Russia? China? India?) In practice, the prospect of such payments encourages all states to display reluctance in hopes of being paid.
— The distribution of power among states could hardly be less conducive to an agreement. The states best able to implement controls are those with high and rising emissions and disproportionate bargaining power in world politics. Yet these countries appear to be the ones least exposed to direct harm. Of course, they must still fear spillovers from disease, migration, poverty, crime and government instability. But these concerns have not been acute enough to lead countries to bear the high and immediate costs of GHG controls.
— The nature of the task empowers hold-outs. Successful controls would require nearly universal cooperation; therefore, go-it-alone power, although it exists, is modest and hold-up power dominates. Third World states have chosen to exploit this fact by demanding financial transfers as the price for their cooperation. Since they would be the main beneficiaries of controls, they are, in effect, demanding to be paid to help themselves.
— The current, incomplete and fragmented global GHG control regime serves more to assuage domestic political interests than as a means to achieve concrete national interests. The countries most committed to containment are the ones that have been rich enough for long enough to develop strong green movements. Such movements are, by their nature, inspired more by symbols than by substance; hence, the Kyoto Protocol, an accord that asked nothing from rapidly growing low- and middle-income countries and thus would have done little to curb GHG emissions even if it had been honored by the signatories, became the holy grail of green causes. Governments subject to demands of this type have strong motives to substitute pomp for substance.
Evidence that emissions-as-usual could lead to catastrophic climate change–say an explosive acceleration of warming from a destabilizing feedback mechanism–might yet alter this recipe for gridlock. But the operative word here is “might.” Unwelcome information is often resisted. And, in any case, bad news wouldn’t make much difference if GHG controls were perceived to be too late to prevent the catastrophe.
Hopes have centered instead on creating a less unwieldy control regime than the UNFCCC–the G-20 countries or the so-called Major Economies Forum. A simpler structure is clearly a necessary step, but I doubt it would be sufficient to make real progress on global emissions containment.
Plan B: The Engineering Option
Those concerned about the potential harm from climate change, but mindful of GHG controls’ high costs and dim prospects, have had little choice but to seek other options. One would be to try to engineer the climate in ways that restrain warming despite the continued rise in GHG levels in the atmosphere.
This idea is gaining political and technical credibility. The U.S. House of Representatives, the British House of Commons and the European Union have each launched investigations of the potential for climate engineering. The Royal Society in the UK has recently issued a research report. And several private-sector studies are under way.
CE works by offsetting the heat-trapping effect of GHGs in the atmosphere by reducing the amount of solar energy available to be trapped. CE would not lower GHG concentrations; rather, it would reflect a portion of the incoming sunlight back into space.
To make a difference the energy mirrored back into space need not be that great. Reflecting one to two percent of the sunlight that reaches the Earth could roughly offset the warming that is likely to result from doubling pre-industrial levels of GHGs. Today’s aerosol emissions (a variety of non-GHG air pollutants) are already offsetting about 40 percent of the warming that man-made GHG emissions would otherwise have caused. CE aims to extend the scale of this effect while causing fewer and less costly side-effects.
At least two CE technologies may offer workable means of offsetting the warming expected in this century. One of these, proposed by Edward Teller (yes, the Edward Teller) and colleagues, involves injecting very fine sulfate particles into the stratosphere. After perhaps a year or two, these particles would fall to the surface in acidic rain or snow. But the quantities would be quite small compared to baseline industrial sulfur emissions, which have much less protective effect because of their large particle size and low altitude. The global cooling that has occurred in the wake of several volcanic eruptions offers an analogue to this concept and suggests–though it does not prove–that the process could effectively cool the planet.
The second approach, developed by John Latham and Stephen Salter, involves lofting a fine mist of seawater droplets into low-level marine clouds. There, the droplets would cause the clouds both to “whiten”–that is, to reflect more sunlight–and to increase their stability. Climate models suggest that this approach might cool the planet enough to offset the warming caused by doubling atmospheric GHG levels.
The somewhat uneven geographic impact of this latter approach would increase the prospects of unwanted regional effects. However, this very unevenness may offer a means of fine-tuning the regional impact of CE cooling where it was undesirable.
The rapid emergence of CE as an option has triggered a diverse range of objections. Some green advocacy groups view the control of GHG emissions as a means to the greater end of defeating materialism and the hubris of attempting to dominate nature. If CE proves to be a technologically viable alternative, it would both delay the need for emissions controls and affirm human command over the climate.
Among climate scientists, reactions have varied. One school of thought has come to regard CE as being much like chemotherapy–no one wants to have it, but everyone wants the option should the need arise. A second camp seems to feel that some research is acceptable, but that large scale tests would not be; a third is ethically opposed to any research.
The potential benefits of CE are very large compared to the likely costs of developing and deploying it. Of course, the net potential benefits depend on the severity of the threat from climate change and the type of GHG control regime that would otherwise be needed to achieve the same end. Eric Bickel of the University of Texas has estimated that, if CE were held in reserve and used in the event of a climate emergency, the net benefits of the option would be as high as $14 trillion. Other scenarios yield similarly dramatic estimates.
Against this potential benefit must be weighed several kinds of risks. CE, might, for example, change global precipitation patterns. One major concern is a possible impact on India’s summer monsoon, which plays a key role in the subcontinent’s agricultural output. Current models are still too imperfect even to determine the direction of the effect on the monsoon, which may also be threatened by warming.
CE may generate other unwanted side effects, too. The early use of sulfur aerosols in the stratosphere could delay recovery of the damage to the ozone layer before the containment of CFC gases used in air conditioning. Skies might appear to be somewhat whiter; there would be a small increase in acid precipitation from sulfur aerosol injections. The identified risks appear to be small, however, and the larger fears center on what amounts to unknown unknowns.
It is also very important to note that CE could not be a complete response to the threats posed by rising GHG levels. CE could do nothing to curb ecological harm from ocean acidification from absorption of carbon dioxide. Further, over time the effectiveness of CE might well be subject to diminishing returns. It might, however, reduce the need for controls in the short- and medium-terms–and, given the performance of the UNFCCC process, that might be a boon of no small worth.
While the benefit-cost ratio of CE would probably be quite large, there is more to the story. For CE development costs–unlike the development costs of virtually all other sorts of large-scale engineering projects–are almost laughably small in absolute terms.
Initial research would cost a few tens of millions of dollars per year. Scaled-up experiments would probably cost a few billion dollars, with much of the money spent on monitoring the system’s full range of global effects.
To be sure, a full-blown stratospheric aerosol system would be much more expensive–perhaps more than $50 billion a year although more recent research seems to be sharply lowering this estimate. But this number is still an order of magnitude less than the potential benefits–or the cost of a workable emissions containment regime.
Note, too, that CE might produce large global net benefits and still cause harm to some regions–for example, from unwanted cooling in countries like Russia. One could imagine the need, then, for side-payments from winners to losers to manage international conflicts. And such compensation might well dwarf the direct cost of the climate engineering itself.
Finally, as mentioned above, the impact of CE is subject to large uncertainties. Countries cannot know exactly what will happen as a CE system is deployed; thus much trial and error will be built into the task of managing CE. New knowledge is likely to suggest new approaches and refinements to the CE system, and those approaches will require testing–from which further lessons will flow. Each change could alter the distribution of costs and benefits among states, requiring the need for ongoing bargaining over burdens and side-payments.
The Power Politics of CE
While a medium-sized state might well acquire the technology and resources to put in place a global CE system, it would be unlikely to act in the teeth of opposition from the major powers. In contrast, a great power might well persevere even in the face to peer pressure to halt. For such states, go-it-alone power in regard to CE is far stronger than hold-up power. This situation is the opposite of that which prevails with GHG control: Sanctions would be a costly and impractical tool for exercising hold-up power against the United States, China, Russia or the European Union.
A military response designed to stop CE is even less plausible, although some opponents of CE have warned of future climate engineering wars. The great powers, after all, are all nuclear states. Remember, too, that at least for the remainder of this century, the cooling needed to limit temperatures to the two degree Celsius increase widely viewed as acceptable would be relatively modest. The odds are, then, that the potential costs of using armed force will dwarf any perceived harm of allowing neighbors to impose CE on others.
Another option may, however, offer a stronger check on CE: climate counter-engineering. Black carbon emissions could be used to warm the lower atmosphere, and there would be a multiplier effect as the particles fell and the darker color increased sunlight absorbed on the earth’s surface. The technology of counter-engineering is extremely simple. Merely taking the particulate filters off coal-fired power plants would generate the desired warming emissions.
Of course, counter-engineering has its downside for the country that attempts it. Today, states pay to avoid black carbon emissions’ impacts on health and property, and it is hard to imagine a democracy resorting to such an option. But authoritarian states might well credibly threaten to release carbon particulates. Russia, the large country with the most to gain from warming, is an obvious candidate.
Some analysts, looking only at predictions that CE will be cheap to deploy, have leapt to the conclusion that unilateral CE–say, by China or the United States–posed a grave risk. Their concern is not entirely groundless. But a variety of factors will be working to constrain unilateral imposition of CE.
— At some point CE will reach a stage at which it will become necessary to test the climate’s responses to it. As the tests grow in size, the risk of one approach interfering with another would rise. So if more than one country becomes CE-capable, there will be pressure for cooperation among them.
— A stable climate is hardly the only objective of sovereign governments, so countries will have good reason to shield the vital interests of their allies in deciding whether or not to deploy CE. The United States, for instance, is likely to value a strong, stable India. Any scheme that would endanger the Indian summer monsoon would, therefore, be a cause for concern in the United States. It follows that, if the United States did choose to go forward with CE, it would be willing to entertain ways to protect India from adverse consequences. China, to be sure, might be less fastidious in weighing its own benefits against others’ costs. But China is economically vulnerable to western countries; it would not lightly ignore the threat of trade sanctions.
— More generally, global interdependence reinforces open societies’ interest in the stability and welfare of other nations. In short, linked markets and mobile populations broaden the definition of enlightened national self-interest. Developed states are increasingly afraid of climate change spillovers from the Third World, and harmful CE spillovers, whatever form that might take, would be equally unwelcome.
— Democracies are constrained by domestic pressure groups, and they are likely to impose tight limits on CE. In the EU, opposition from the greens may sink CE proposals entirely. In the United States, the split between a left impelled by a quasi-religious commitment to GHG controls and a right unpersuaded of the seriousness of climate change could yield a similar outcome. Thus, short of a clear global climate crisis, it is hard to see democracies nations acting alone on CE.
— The possibility climate counter-engineering reinforces the grounds for caution. It may be an effective check on CE go-it-alone power. And at least one technologically advanced country, Russia, has both the capacity and the motivation to use the option if challenged.
The Road Not Yet Travelled
I believe that the United Nations regime focusing on GHG control is beyond repair. And with emissions containment stalled, the world needs an alternative.
The road to creating an effective CE initiative is bound to be bumpy. To work well, a CE management structure would have to limit real control to a few of the most powerful states. This may seem unfair, and perhaps it is unfair. What’s more, CE would open the door to environmental harm that can’t be properly assayed without years of research and testing. But for those of us who believe that climate change might, at some point, pose a grave threat–and that emissions containment is both costly and politically impractical–CE is beginning to look like the last best hope.
Lee Lane is a resident fellow at AEI.
Photo Credit: iStockphoto/Jan Rysavy |
