The Other Climate Changers

Why and Ozone Also Matter

Jessica Seddon Wallack and Veerabhadran Ramanathan

At last, world leaders have recognized that total contribution to the level of carbon is a threat. And to slow or dioxide in the atmosphere would still reverse it, they are launching initiatives have increased by a third since the begin- to reduce greenhouse gases, especially ning of this century. , the gas responsible for Meanwhile, little attention has been about half of global warming to date. given to a low-risk, cost-eªective, and Significantly reducing emissions of carbon high-reward option: reducing emissions dioxide is essential, as they will likely of light-absorbing carbon particles (known become an even greater cause of global as “black carbon”) and of the gases that warming by the end of this century. But it form ozone. Together, these pollutants’ is a daunting task: carbon dioxide remains warming eªect is around 40–70 percent in the atmosphere for centuries, and it is of that of carbon dioxide. Limiting their di⁄cult to get governments to agree on presence in the atmosphere is an easier, reducing emissions because whereas the cheaper, and more politically feasible benefits of doing so are shared globally, proposition than the most popular pro- the costs are borne by individual countries. posals for slowing climate change—and As a result, no government is moving fast it would have a more immediate eªect. enough to oªset the impact of past and Time is running out. Humans have present emissions. Even if current emis- already warmed the planet by more than sions were cut in half by 2050—one of the 0.5 degrees Celsius since the nineteenth targets discussed at the 2008 un Climate century and produced enough greenhouse Change Conference—by then, humans’ gases to make it a total of 2.4 degrees

Jessica Seddon Wallack is Director of the Center for Development Finance at the Institute for Financial Management and Research, in , . Veerabhadran Ramanathan is Distinguished Professor of Climate and Atmospheric Sciences at the Scripps Institute of Oceanography at the University of California, San Diego; Distinguished Visiting Fellow at the Energy and Resources Institute, in New Delhi; and a recipient of the 2009 Tyler Prize for Environmental Achievement.

[105] Jessica Seddon Wallack and Veerabhadran Ramanathan Celsius warmer by the end of this century. ments on drones, aircraft, ships, and satel- If the levels of carbon dioxide and nitrous lites to track black carbon and ozone from oxide in the atmosphere continue to in- their sources to remote locations thousands crease at current rates and if the climate of miles away and measure and model how proves more sensitive to greenhouse gases much atmospheric heating they cause. than predicted, the earth’s temperature Black carbon, a widespread form of could rise by as much as five degrees before particulate air pollution, is what makes the century ends. sooty smoke look blackish or brownish. A temperature change of two to five It is a byproduct of incomplete, ine⁄cient degrees would have profound environ- combustion—a sign of energy waste as mental and geopolitical eªects. It would much as energy use. Vehicles and ships almost certainly melt all the Arctic summer fueled by diesel and cars with poorly sea ice. As a result, the Arctic Ocean would maintained engines release it. So do absorb more sunlight, which, in turn, forest fires and households and factories would further amplify the warming. Such that use wood, dung, crop waste, or coal a rise could eliminate the Himalayan and for cooking, heating, or other energy needs. Tibetan glaciers, which feed the major Black carbon alters the environment water systems of some of the poorest in two ways. In the sky, the suspended regions of the world. It would also accel- particles absorb sunlight, warming up the erate the melting of the Greenland and atmosphere and in turn the earth itself. Antarctic ice sheets, raising the sea level On the earth’s surface, deposits of black worldwide and provoking large-scale carbon on snowpacks and ice absorb emigration from low-lying coastal regions. sunlight, thereby heating the earth and Cycles of droughts and floods triggered melting glaciers. The Arctic sea ice and by global warming would spell disaster the Himalayan and Tibetan glaciers, for for agriculture-dependent economies. example, are melting as much as a result of Some of global warming’s environmen- black carbon as they are as a result of the tal eªects would be irreversible; some of global warming caused by carbon dioxide. its societal impacts, unmanageable. Given The warming eªect of black carbon is equal these consequences, policymakers world- to about 20–50 percent of the eªect of wide seeking to slow climate change must carbon dioxide, making it the second- or weigh options beyond just reducing carbon third-largest contributor to global warming. dioxide, especially those that would pro- No one knows exactly how much warming duce rapid results. Cutting black carbon it causes, but even the most conservative and ozone is one such strategy. estimates indicate a nontrivial impact. And its large contribution to the melting POWERFUL POLLUTANTS of glaciers and sea ice, one of the most The warming eªect of carbon dioxide has alarming near-term manifestations of been known since at least the 1900s, and climate change, is well documented. that of ozone since the 1970s, but the The ozone in the lower level of the importance of black carbon was discovered atmosphere is another major contributor only recently. During the past decade, to global warming that deserves attention. scientists have used sophisticated instru- (This is diªerent from the ozone in the

[106] foreign affairs . Volume 88 No. 5 The Other Climate Changers stratosphere, which shields life on earth change. Reducing the emissions of from the sun’s ultraviolet rays.) A potent these pollutants on earth would quickly , its warming eªect is lower their concentrations in the atmos- equal to about 20 percent of that of carbon phere and, in turn, reduce their impact dioxide. Unlike black carbon, which exists on global warming. as particles, ozone is a gas. Ozone in the atmosphere is not emitted directly but AN EASIER EXTRA STEP formed from other gases, “ozone precur- Another promising feature of black carbon sors,” such as carbon monoxide (from the and ozone precursor emissions is that they burning of fossil fuels or biomass), nitrogen can be significantly limited at relatively low oxides (from lightning, soil, and the burning cost with technologies that already exist. of fossil fuels), methane (from agriculture, Although the sources of black carbon and cattle, gas leaks, and the burning of wood), ozone precursors vary worldwide, most and other hydrocarbons (from the burning emissions can be reduced without neces- of organic materials and fossil fuels, among sarily limiting the underlying activity that other sources). generated them. This is because, unlike Most important, black carbon and carbon dioxide, black carbon and ozone ozone stay in the atmosphere for a much precursors are not essential byproducts shorter time than does carbon dioxide. of energy use. Carbon dioxide remains in the atmosphere The use of fossil fuels, particularly for centuries—maybe even millennia— diesel, is responsible for about 35 percent before it is absorbed by oceans, plants, and of black carbon emissions worldwide. algae. Even if all carbon dioxide emissions Technologies that filter out black carbon were miraculously halted today, it would have already been invented: diesel partic- take several centuries for the amount ulate filters on cars and trucks, for example, of carbon dioxide in the atmosphere to can reduce black carbon emissions by approach its preindustrial-era level. In 90 percent or more with a negligible contrast, black carbon stays in the atmos- reduction in fuel economy. A recent study phere for only days to weeks before it is by the Clean Air Task Force, a U.S. non- washed away by rain, and ozone (as well profit environmental research organization, as some of its precursors) only stays for estimated that retrofitting one million weeks to months before being broken semitrailer trucks with these filters would down. Nonetheless, because both are yield the same benefits for the climate over widespread and continuously emitted, their 20 years as permanently removing over atmospheric concentrations build up and 165,000 trucks or 5.7 million cars from cause serious damage to the environment. the road. Although reducing the emissions of The remaining 65 percent of black other greenhouse gases, such as methane carbon emissions are associated with the and halocarbons, could also produce burning of biomass—through naturally immediate results, black carbon and ozone occurring forest fires, man-made fires for are the shortest-lived climate-altering clearing cropland, and the use of organic pollutants, and they are relatively under- fuels for cooking, heating, and small-scale recognized in eªorts to stem climate industry. Cleaner options for the man-made

foreign affairs . September / October 2009 [107] Jessica Seddon Wallack and Veerabhadran Ramanathan activities exist. The greenest options for another decade’s worth. Within weeks, households are stoves powered by the sun the heating eªect of black carbon would or by gas from organic waste, but updated lessen; within months, so, too, would the designs for biomass-fueled stoves can greenhouse eªect of ozone. Within ten also substantially cut the amount of black years, the earth’s overall warming trend carbon and other pollutants emitted. Crop would slow down, as would the retreat of waste, dung, wood, coal, and charcoal are sea ice and glaciers. The scientific argu- the cheapest, but also the least e⁄cient ment for reducing emissions of black and dirtiest, fuels, and so households tend carbon and ozone precursors is clear. to shift away from them as soon as other options become reliably available. Thus, A POLITICAL POSSIBILITY the challenge in lowering black carbon Reducing emissions of black carbon emissions is not convincing people to and ozone precursors is also a politically sacrifice their lifestyles, as it is with con- promising project. It would yield signifi- vincing people to reduce their carbon cant benefits apart from slowing climate dioxide emissions. The challenge is to change, giving governments economic make other options available. and developmental incentives to reduce Man-made ozone precursors are mostly them. Reducing ozone precursors, for its emitted through industrial processes and part, would have recognizable agricultural fossil-fuel use, particularly in the trans- benefits. Ozone lowers crop yields by portation sector. These emissions can be damaging plant cells and interfering with reduced by making the combustion process the production of chlorophyll, the pig- more e⁄cient (for example, through the ment that enables plants to derive energy use of fuel additives) or by removing these from sunlight. One recent study estimated gases after combustion (for example, that the associated economic loss (at through the use of catalytic converters). 2000 world prices) ranged from $14 billion Technologies that both minimize the to $26 billion, three to five times as large formation of ozone precursors and filter as that attributed to global warming. For or break down emissions are already widely policymakers concerned about agricultural used and are reducing ozone precursors productivity and food security, these eªects in the developed world. The stricter should resonate deeply. enforcement of laws that forbid adulter- In countries where a large portion of ating gasoline and diesel with cheaper, the population still depends on biomass but dirtier, substitutes would also help. fuels, reducing black carbon emissions Fully applying existing emissions-control from households would improve public technologies could cut black carbon emis- health and economic productivity. Nearly sions by about 50 percent. And that would 50 percent of the world’s population, and be enough to oªset the warming eªects of up to 95 percent of the rural population in one to two decades’ worth of carbon dioxide poor countries, relies on solid fuels, includ- emissions. Reducing the human-caused ing biomass fuels and coal. The resulting ozone in the lower atmosphere by about indoor air pollution is linked to about a 50 percent, which could be possible through third of the fatal acute respiratory infections existing technologies, would oªset about among children under five, or about

[108] foreign affairs . Volume 88 No. 5 The Other Climate Changers seven percent of child deaths worldwide. part to the areas where reductions were Respiratory illnesses associated with the achieved. The melting of the Himalayan emissions from solid fuels are the fourth and Tibetan glaciers is almost reason most important cause of excess mortality enough for countries in South and East in developing countries (after malnutrition, Asia to take rapid action to eliminate unsafe sex, and waterborne diseases). black carbon emissions. So is the retreat These health problems perpetuate of the Arctic sea ice for countries bordering poverty. Exposure to pollutants early in the Arctic Ocean. Regional groupings are life harms children’s lung development, also more likely than larger collections and children who suªer from respiratory of countries to have dense networks of illnesses are less likely to attend school. the economic, cultural, and diplomatic Air pollution leaves the poor, who often ties that sustain di⁄cult negotiations. earn a living from manual labor, especially Moreover, both black carbon and ozone worse oª. Collectively, workers in India can be contained through geographically lose an estimated 1.6–2.0 billion days of targeted strategies because many of the work every year to the eªects of indoor sources of black carbon and ozone are air pollution. Reducing black carbon largely fixed. And so even if one country emissions from households would thus in a region seeks to regulate emissions, promote economic growth and, particularly that country’s polluting activities are for rural women and children, improve unlikely to move to another country public health. with less stringent policies—a common Furthermore, both black carbon and concern with agreements to reduce carbon ozone precursor emissions tend to have dioxide emissions. localized consequences, and governments are more likely to agree to emissions- CLEANING UP reduction strategies that can deliver local So what can be done to curb black carbon benefits. With carbon dioxide and other and ozone precursor emissions? A logical long-lasting, far-spreading greenhouse first step is for governments, international gases, emissions anywhere contribute to development agencies, and philanthropists global warming everywhere. But the to increase financial support for reduction eªects of black carbon and ozone are eªorts. Although some money for this is more confined. When it first enters the currently available, neither pollutant has atmosphere, black carbon spreads locally emerged as a mainstream target for public and then, within a week, dissipates more or private funding. Simply recognizing regionally before disappearing from the black carbon and ozone as environmental atmosphere entirely in the form of precip- problems on par with carbon dioxide itation. Ozone precursors, too, are more would make policymakers more inclined regionally confined than carbon dioxide, to spend development funds and the although background levels of ozone are “green” portions of stimulus packages increasing around the globe. on initiatives to tackle them. Developed Because the eªects of black carbon and countries could put their contributions ozone are mostly regional, the benefits toward customizing emissions-reduction from reducing them would accrue in large technologies for the developing world

foreign affairs . September / October 2009 [109] Jessica Seddon Wallack and Veerabhadran Ramanathan and promoting their deployment—an farming. Other development initiatives important gesture of goodwill that would have influenced fertility, gender equality, kick-start change. schooling, and other household decisions Regardless of the source of the funding, more sensitive than those about cooking aid should support the deployment of and driving. clean-energy options for households and Moreover, the infrastructure for inter- small industries in the developing world national financial and technological and of emissions-reduction technologies transfers already exists in the form of for transportation around the world. This the World Bank, regional development could mean distributing solar lanterns and banks, and un programs that have sup- stoves that use local fuel sources more ported development around the world e⁄ciently or paying for small enterprises for decades. The Global Environment to shift to cleaner technologies. The Facility, a development and environmental specific fixes for small-scale industry will fund that started as a World Bank program vary by economic activity—making brick and is now the world’s largest funder of kilns cleaner is diªerent from making tea environmental projects, is well suited to and spice driers more e⁄cient—but the finance cleaner technologies. number of possible customers for the Governments and international agen- new technologies oªers some economies cies should also finance technology that of scale. When it comes to transportation, tracks air quality, which is generally policy options include subsidizing engine undermonitored. In the major cities of and filter upgrades, shifting to cleaner most developing countries, the number fuels, and removing the incentives, created of sensors has not kept up with the growth by government subsidies that favor some in population or economic activity. In rural fuels over others, for adulterating fuel and areas, air pollution is not tracked at all. for using diesel. Improving the monitoring of air quality Deploying technologies to reduce emis- and disseminating the data would inform sions from so many culturally embedded policymakers and environmental activists. activities, from cooking to driving, will And tracking individuals’ emissions— not be easy. Enforcing emissions controls through indoor air-pollution monitors or on many small, mobile polluters is harder devices attached to cars’ tailpipes—could than regulating larger sources, such as help motivate people to curb their emis- power plants. And in customizing tech- sions. Experimental initiatives to measure nologies, close attention will need to be individuals’ carbon footprints and energy paid to the varied needs of households use have been shown to change people’s and industry. But creating and enforcing behavior in some settings. regulations and subsidizing and dissemi- Aid alone will not be enough, however. nating energy-e⁄cient technologies are International organizations must also challenges that have been met before. The help governments identify and act on “green revolution”—the remarkable growth opportunities that mitigate climate change in agricultural productivity that occurred in and promote development. International the second half of the twentieth century— development institutions, such as the introduced radical changes to small-scale un Environment Program and the multi-

[110] foreign affairs . Volume 88 No. 5 lateral and regional development banks, could sponsor research, set up intermin- isterial working groups, and establish standards for monitoring and reporting public expenditures. These initiatives would make it easier to identify possible areas of coordination among public health, agricultural, environmental, and anti- poverty programs. In most countries, domestic institutions are not designed to encourage cooperation among diªerent authorities. Pitching the reduction of black carbon and ozone precursor emis- sions as public health and agricultural policies could help such eªorts compete for scarce funds; enabling the clearer calculation of the environmental benefits of development policies would make policymaking more informed. Much in the same way that international develop- ment organizations currently support good governance to improve infrastructure and services, they should also promote better environmental governance.

RESPONDING REGIONALLY The current piecemeal approach to climate science—in particular, the tendency to treat air pollution and climate change as separate issues—has at times led to bad policy. The decision of many coun- tries to promote diesel as a means to encourage fuel e⁄ciency, for example, may have had the inadvertent eªect of increasing black carbon emissions. And air-pollution laws designed to reduce the use of sulfate , which cause acid rain, have ironically led to more warming because sulfates also have a cooling eªect. Had policymakers in- stead integrated eªorts to reduce air pollution with those to slow global warming, they could have ensured that

[111] Jessica Seddon Wallack and Veerabhadran Ramanathan the reduction of sulfates was accompanied Transboundary Air Pollution (most of by an equivalent reduction in green- whose signatories are European or Central house gases. Asian states) and its subsequent pollutant- A single global framework would be specific protocols provide a ready model the ideal way to integrate various strategies for regional agreements on short-lived for mitigating climate change. Bilateral or climate-changing pollutants. The specific multilateral agreements are more feasible provisions of these agreements are based for getting started on reducing black car- on the costs of reductions, scientists’ bon and ozone precursor emissions. These knowledge of the sources and distribu- can strengthen governments’ incentives tion of air pollution, and the ability to to act by discouraging free-riding and by measure reductions—considerations motivating governments to take into ac- that should also inform the regulation of count the larger-scale impacts of their black carbon and ozone precursor emis- own emissions. Because the sources of sions. Moreover, these agreements commit black carbon and ozone vary from region to countries to particular actions, not just region, agreements to reduce them need specific outcomes. This is wise, given that to be tailored to suit regional conditions. emissions are di⁄cult to monitor and In the Northern Hemisphere, for example, quantify precisely. ozone precursors mostly come from Black carbon and ozone can also be industrial processes and transportation, built into existing bilateral discussions. whereas in the Southern Hemisphere, The High-Level India-eu Dialogue, a especially tropical regions, they mostly working group of scientists and policy- come from natural emissions (soils, plants, makers from Europe and India, is one and forest fires). The sources of black such existing forum. In February 2009, carbon vary by region, too: in Europe it was already urging governments from and North America, transportation and Europe and India to work together to industrial activity play a larger role than recognize and reduce the threat from the burning of biomass, whereas the black carbon. Participants proposed an reverse is true in developing regions. interdisciplinary research project that The impact of emissions on the climate would determine the eªects of biomass- is scientifically complex, and it depends based cooking and heating on health and on a number of factors that have not yet the climate and assess the obstacles to a been adequately taken into account when large-scale deployment of cleaner stoves. devising climate models. The challenge, Black carbon and ozone are also natural then, is to quickly create agreements candidates for U.S.-Chinese cooperation that consider the complex links between on energy and climate change: China human activities, emissions, and climate would reap public health and agricultural change and that can adjust over time as benefits from reducing emissions, and the scientific understanding of the the United States would earn goodwill problem evolves. Regional air-pollution for helping China do so. agreements are easier to update than By building on existing air-pollution global agreements with many signatories. agreements, the risk of distracting climate- The un Convention on Long-Range change negotiations from the substantial

[112] foreign affairs . Volume 88 No. 5 The Other Climate Changers task of promoting the reduction of carbon to get oª the ground. These pollutants dioxide emissions could be avoided. are also tractable policy targets: they can Putting black carbon and ozone on the be reduced through the use of existing table in high-level climate talks could technologies, institutions, and strategies, backfire if developing nations thought that and doing so would lead to local improve- they would be tacitly admitting responsi- ments in air quality, agricultural output, bility for global warming by committing and public health. In short, reducing black to reducing emissions of black carbon and carbon and ozone precursor emissions is ozone precursors or believed that the issue a low-risk, high-potential addition to the was an eªort by developed countries to current arsenal of strategies to mitigate divert attention from the need for them climate change. to reduce their carbon dioxide emissions. At the current rate of global warming, Therefore, eªorts to reduce emissions of the earth’s temperature stands to careen black carbon and ozone precursors should out of control. Now is the time to look be presented not as substitutes for commit- carefully at all the possible brakes that ments to reducing carbon dioxide emissions can be applied to slow climate change, but as ways to quickly achieve local envi- hedge against near-term climate disasters, ronmental and economic benefits. and buy time for technological innovations. Of the available strategies, focusing on THE LOW-HANGING FRUIT reducing emissions of black carbon and Historically, initiatives to slow global ozone precursors is the low-hanging warming have focused on reducing the fruit: the costs are relatively low, the im- emissions of carbon dioxide and other plementation is feasible, and the benefits greenhouse gases and largely ignored the would be numerous and immediate.∂ role played by air pollution. This strategy makes sense for the long run, since carbon dioxide emissions are, and will continue to be, the most important factor in climate change. But in the short run, it alone will not be enough. Some scientists have pro- posed geoengineering—manipulating the climate through the use of technology— as a potential option of last resort, but the reduction of black carbon and ozone precursor emissions oªers a less risky opportunity for achieving the same end. Such an approach would quickly lower the level of black carbon and ozone in the atmosphere, oªsetting the impact of decades of greenhouse gas emissions, decelerating the rush toward a danger- ously warm planet, and giving eªorts to reduce carbon dioxide emissions time

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