THE HANDSTAND

SEPTEMBER 2006
One of America's top scientists has said that the world has already entered a state of dangerous climate change.

In his first broadcast interview as president of the American Association for the Advancement of Science, John Holdren told the BBC that the climate was changing much faster than predicted. "We are not talking anymore about what climate models say might happen in the future. "We are experiencing dangerous human disruption of the global climate and we're going to experience more," Professor Holdren said.

He blamed President Bush not only for refusing to cut emissions, but also for failing to live up to his rhetoric on harnessing technology to tackle climate change. "We are not starting to address climate change with the technology we have in hand, and we are not accelerating our investment in energy technology research and development," Professor Holdren observed. He said research undertaken by Harvard University revealed that US government spending on energy research had not increased since 2001. In order to make any progress, funding for climate technology needed to multiply by three or four times, Professor Holdren warned.

Last year, the UK's Prime Minister, Tony Blair, held a science conference to determine the threshold of dangerous climate change. Delegates concluded that to be relatively certain of keeping the rise below 2C (3.6F), CO2 levels in the atmosphere should not exceed 400 parts per million (ppm) and the highest prudent limit should be 450 ppm.

BBC World News



TWO ARTICLES INTRODUCING CARBON CONTROL OPTIONS FROM SCIENTIFIC AMERICAN

ARTICLE NO 1.
This article focuses on ways to control the emission of carbon dioxide from fossil fuels like coal, oil, and natural gas. The article claims that humanity can emit only so much carbon dioxide into the atmosphere before the climate enters a geologic state unknown to history. Climate scientists see the risks growing rapidly as CO<sub>2</sub> levels are near to double what they were before the 18th century.
A Plan to Keep Carbon in Check
ENVIRONMENTAL policy
*FOSSIL fuels
CARBON
CARBON dioxide
CLIMATIC changes
GREENHOUSE gas mitigation

SOCOLOW, ROBERT H.
Socolow, Robert H.1,2
PACALA, STEPHEN W.
Pacala, Stephen W.1,3,4
Scientific American; Sep2006, Vol. 295 Issue 3, p50-57, 8p, 1 chart, 6 graphs, 1 map, 1c

Section: A PRAGMATIC PROGRAM
A Plan to Keep Carbon in Check

Getting a grip on greenhouse gases is daunting but doable. The technologies already exist. But there is no time to lose

Retreating glaciers, stronger hurricanes, hotter summers, thinner polar bears: the ominous harbingers of global warming are driving companies and governments to work toward an unprecedented change in the historical pattern of fossil-fuel use. Faster and faster, year after year for two centuries, human beings have been transferring carbon to the atmosphere from below the surface of the earth. Today the world's coal, oil and natural gas industries dig up and pump out about seven billion tons of carbon a year, and society burns nearly all of it, releasing carbon dioxide (CO2). Ever more people are convinced that prudence dictates a reversal of the present course of rising CO2 emissions.

The boundary separating the truly dangerous consequences of emissions from the merely unwise is probably located near (but below) a doubling of the concentration of CO2 that was in the atmosphere in the 18th century, before the Industrial Revolution began. Every increase in concentration carries new risks, but avoiding that danger zone would reduce the likelihood of triggering major, irreversible climate changes, such as the disappearance of the Greenland ice cap. Two years ago the two of us provided a simple framework to relate future CO2 emissions to this goal.

We contrasted two 50-year futures. In one future, the emissions rate continues to grow at the pace of the past 30 years for the next 50 years, reaching 14 billion tons of carbon a year in 2056. (Higher or lower rates are, of course, plausible.) At that point, a tripling of preindustrial carbon concentrations would be very difficult to avoid, even with concerted efforts to decarbonize the world's energy systems over the following 100 years. In the other future, emissions are frozen at the present value of seven billion tons a year for the next 50 years and then reduced by about half over the following 50 years. In this way, a doubling of CO2 levels can be avoided. The difference between these 50-year emission paths--one ramping up and one flattening out--we called the stabilization triangle.

To hold global emissions constant while the world's economy continues to grow is a daunting task. Over the past 30 years, as the gross world product of goods and services grew at close to 3 percent a year on average, carbon emissions rose half as fast. Thus, the ratio of emissions to dollars of gross world product, known as the carbon intensity of the global economy, fell about 1.5 percent a year. For global emissions to be the same in 2056 as today, the carbon intensity will need to fall not half as fast but fully as fast as the global economy grows.

Two long-term trends are certain to continue and will help. First, as societies get richer, the services sector--education, health, leisure, banking and so on--grows in importance relative to energy-intensive activities, such as steel production. All by itself, this shirt lowers the carbon intensity of an economy.

Second, deeply ingrained in the patterns of technology evolution is the substitution of cleverness for energy. Hundreds of power plants are not needed today because the world has invested in much more efficient refrigerators, air conditioners and motors than were available two decades ago. Hundreds of oil and gas fields have been developed more slowly because aircraft engines consume less fuel and the windows in gas-heated homes leak less heat.

The task of holding global emissions constant would be out of reach, were it not for the fact that all the driving and flying in 2056 will be in vehicles not yet designed, most of the buildings that will be around then are not yet built, the locations of many of the communities that will contain these buildings and determine their inhabitants' commuting patterns have not yet been chosen, and utility owners are only now beginning to plan for the power plants that will be needed to light up those communities. Today's notoriously inefficient energy system can be replaced if the world gives unprecedented attention to energy efficiency. Dramatic changes are plausible over the next 50 years because so much of the energy canvas is still blank.

To make the task of reducing emissions vivid, we sliced the stabilization triangle into seven equal pieces, or "wedges," each representing one billion tons a year of averted emissions 50 years from now (starting from zero today). For example, a car driven 10,000 miles a year with a fuel efficiency of 30 miles per gallon (mpg) emits close to one ton of carbon annually. Transport experts predict that two billion cars will be zipping along the world's roads in 2056, each driven an average of 10,000 miles a year. If their average fuel efficiency were 30 mpg, their tailpipes would spew two billion tons of carbon that year. At 60 mpg, they would give off a billion tons. The latter scenario would therefore yield one wedge.

Wedges

IN OUR FRAMEWORK, you are allowed to count as wedges only those differences in two 2056 worlds that result from deliberate carbon policy. The current pace of emissions growth already includes some steady reduction in carbon intensity. The goal is to reduce it even more. For instance, those who believe that cars will average 60 mpg in 2056 even in a world that pays no attention to carbon cannot count this improvement as a wedge, because it is already implicit in the baseline projection.

Moreover, you are allowed to count only strategies that involve the scaling up of technologies already commercialized somewhere in the world. You are not allowed to count pie in the sky. Our goal in developing the wedge framework was to be pragmatic and realistic--to propose engineering our way out of the problem and not waiting for the cavalry to come over the hill. We argued that even with these two counting rules, the world can fill all seven wedges, and in several different ways. Individual countries--operating within a framework of international cooperation--will decide which wedges to pursue, depending on their institutional and economic capacities, natural resource endowments and political predilections.

To be sure, achieving nearly every one of the wedges requires new science and engineering to squeeze down costs and address the problems that inevitably accompany widespread deployment of new technologies. But holding CO2 emissions in 2056 to their present rate, without choking off economic growth, is a desirable outcome within our grasp.

Ending the era of conventional coal-fired power plants is at the very top of the decarbonization agenda. Coal has become more competitive as a source of power and fuel because of energy security concerns and because of an increase in the cost of oil and gas. That is a problem because a coal power plant burns twice as much carbon per unit of electricity as a natural gas plant. In the absence of a concern about carbon, the world's coal utilities could build a few thousand large ( 1,000-megawatt) conventional coal plants in the next 50 years. Seven hundred such plants emit one wedge's worth of carbon. Therefore, the world could take some big steps toward the target of freezing emissions by not building those plants. The time to start is now. Facilities built in this decade could easily be around in 2056.

Efficiency in electricity use is the most obvious substitute for coal. Of the 14 billion tons of carbon emissions projected for 2056, perhaps six billion will come from producing power, mostly from coal. Residential and commercial buildings account for 60 percent of global electricity demand today (70 percent in the U.S.) and will consume most of the new power. So cutting buildings' electricity use in half--by equipping them with superefficient lighting and appliances--could lead to two wedges. Another wedge would be achieved if industry finds additional ways to use electricity more efficiently.

Decarbonizing the Supply

EVEN AFTER energy-efficient technology has penetrated deeply, the world will still need power plants. They can be coal plants but they will need to be carbon-smart ones that capture the CO2 and pump it into the ground [see "Can We Bury Global Warming?" by Robert H. Socolow; SCIENTIFIC AMERICAN, July 2005]. Today's high oil prices are lowering the cost of the transition to this technology, because captured CO2 can often be sold to an oil company that injects it into oil fields to squeeze out more oil; thus, the higher the price of oil, the more valuable the captured CO2. To achieve one wedge, utilities need to equip 800 large coal plants to capture and store nearly all the CO2 otherwise emitted. Even in a carbon-constrained world, coal mining and coal power can stay in business, thanks to carbon capture and storage.

The large natural gas power plants operating in 2056 could capture and store their CO2, too, perhaps accounting for yet another wedge. Renewable and nuclear energy can contribute as well. Renewable power can be produced from sunlight directly, either to energize photovoltaic cells or, using focusing mirrors, to heat a fluid and drive a turbine. Or the route can be indirect, harnessing hydropower and wind power; both of which rely on sun-driven weather patterns. The intermittency of renewable power does not diminish its capacity to contribute wedges; even if coal and natural gas plants provide the backup power, they run only part-time (in tandem with energy storage) and use less carbon than if they ran all year. Not strictly renewable, but also usually included in the family, is geothermal energy, obtained by mining the heat in the earth's interior. Any of these sources, scaled up from its current contribution, could produce a wedge. One must be careful not to double-count the possibilities; the same coal plant can be left unbuilt only once.

Nuclear power is probably the most controversial of all the wedge strategies. If the fleet of nuclear power plants were to expand by a factor of five by 2056, displacing conventional coal plants, it would provide two wedges. If the current fleet were to be shut down and replaced with modern coal plants without carbon capture and storage, the result would be minus one-half wedge. Whether nuclear power will be scaled up or down will depend on whether governments can find political solutions to waste disposal and on whether plants can run without accidents. (Nuclear plants are mutual hostages: the world's least well-run plant can imperil the future of all the others.) Also critical will be strict rules that prevent civilian nuclear technology from becoming a stimulus for nuclear weapons development. These rules will have to be uniform across all countries, so as to remove the sense of a double standard that has long been a spur to clandestine facilities.

Oil accounted for 43 percent of global carbon emissions from fossil fuels in 2002, while coal accounted for 37 percent; natural gas made up the remainder. More than half the oil was used for transport. So smartening up electricity production alone cannot fill the stabilization triangle; transportation, too, must be decarbonized. As with coal-fired electricity, at least a wedge may be available from each of three complementary options: reduced use, improved efficiency and decarbonized energy sources. People can take fewer unwanted trips (telecommuting instead of vehicle commuting) and pursue the travel they cherish (adventure, family visits) in fuel-efficient vehicles running on low-carbon fuel. The fuel can be a product of crop residues or dedicated crops, hydrogen made from low-carbon electricity, or low-carbon electricity itself, charging an onboard battery. Sources of the low-carbon electricity could include wind, nuclear power, or coal with capture and storage.

Looming over this task is the prospect that, in the interest of energy security, the transport system could become more carbon-intensive. That will happen if transport fuels are derived from coal instead of petroleum. Coal-based synthetic fuels, known as synfuels, provide a way to reduce global demand for oil, lowering its cost and decreasing global dependence on Middle East petroleum. But it is a decidedly climate-unfriendly strategy. A synfuel-powered car emits the same amount of CO2 as a gasoline-powered car, but synfuel fabrication from coal spews out far more carbon than does refining gasoline from crude oil--enough to double the emissions per mile of driving. From the perspective of mitigating climate change, it is fortunate that the emissions at a synfuels plant can be captured and stored. If business-as-usual trends did lead to the widespread adoption of synfuel, then capturing CO2 at synfuels plants might well produce a wedge.

Not all wedges involve new energy technology. If all the farmers in the world practiced no-till agriculture rather than conventional plowing, they would contribute a wedge. Eliminating deforestation would result in two wedges, if the alternative were for deforestation to continue at current rates. Curtailing emissions of methane, which today contribute about half as much to greenhouse warming as CO2, may provide more than one wedge: needed is a deeper understanding of the anaerobic biological emissions from cattle, rice paddies and irrigated land. Lower birth rates can produce a wedge, too--for example, if they hold the global population in 2056 near eight billion people when it otherwise would have grown to nine billion.

Action Plan

WHAT SET OF POLICIES will yield seven wedges? To be sure, the dramatic changes we anticipate in the fossil-fuel system, including routine use of CO2 capture and storage, will require institutions that reliably communicate a price for present and future carbon emissions. We estimate that the price needed to jump-start this transition is in the ballpark of $100 to $200 per ton of carbon--the range that would make it cheaper for owners of coal plants to capture and store CO2 rather than vent it. The price might fall as technologies climb the learning curve. A carbon emissions price of $100 per ton is comparable to the current U.S. production credit for new renewable and nuclear energy relative to coal, and it is about half the current U.S. subsidy of ethanol relative to gasoline. It also was the price of CO2 emissions in the European Union's emissions trading system for nearly a year, spanning 2005 and 2006. (One ton of carbon is carried in 3.7 tons of carbon dioxide, so this price is also $27 per ton of CO2.) Based on carbon content, $100 per ton of carbon is $12 per barrel of oil and $60 per ton of coal. It is 25 cents per gallon of gasoline and two cents per kilowatt-hour of electricity from coal.

But a price on CO2 emissions, on its own, may not be enough. Governments may need to stimulate the commercialization of low-carbon technologies to increase the number of competitive options available in the future. Examples include wind, photovoltaic power and hybrid cars. Also appropriate are policies designed to prevent the construction of long-lived capital facilities that are mismatched to future policy. Utilities, for instance, need to be encouraged to invest in CO2 capture and storage for new coal power plants, which would be very costly to retrofit later. Still another set of policies can harness the capacity of energy producers to promote efficiency--motivating power utilities to care about the installation and maintenance of efficient appliances, natural gas companies to care about the buildings where their gas is burned, and oil companies to care about the engines that run on their fuel.

To freeze emissions at the current level, if one category of emissions goes up, another must come down. If emissions from natural gas increase, the combined emissions from oil and coal must decrease. If emissions from air travel climb, those from some other economic sector must fall. And if today's poor countries are to emit more, today's richer countries must emit less.

How much less? It is easy to bracket the answer. Currently the industrial nations--the members of the Organization for Economic Cooperation and Development (OECD)--account for almost exactly half the planet's CO2 emissions, and the developing countries plus the nations formerly part of the Soviet Union account for the other half. In a world of constant total carbon emissions, keeping the OECD's share at 50 percent seems impossible to justify in the face of the enormous pent-up demand for energy in the non-OECD countries, where more than 80 percent of the world's people live. On the other hand, the OECD member states must emit some carbon in 2056. Simple arithmetic indicates that to hold global emissions rates steady, non-OECD emissions cannot even double.

One intermediate value results if all OECD countries were to meet the emissions-reduction target for the U.K. that was articulated in 2003 by Prime Minister Tony Blair--namely, a 60 percent reduction by 2050, relative to recent levels. The non-OECD countries could then emit 60 percent more CO2. On average, by midcentury they would have one half the per capita emissions of the OECD countries. The CO2 output of every country, rich or poor today, would be well below what it is generally projected to be in the absence of climate policy. In the case of the U.S., it would be about four times less.

Blair's goal would leave the average American emitting twice as much as the world average, as opposed to five times as much today. The U.S. could meet this goal in many ways. These strategies will be followed by most other countries as well. The resultant cross-pollination will lower every country's costs.

Fortunately, the goal of decarbonization does not conflict with the goal of eliminating the world's most extreme poverty. The extra carbon emissions produced when the world's nations accelerate the delivery of electricity and modern cooking fuel to the earth's poorest people can be compensated for by, at most, one fifth of a wedge of emissions reductions elsewhere.

Beyond 2056

THE STABILIZATION triangle deals only with the first 50-year leg of the future. One can imagine a relay race made of 50-year segments, in which the first runner passes a baton to the second in 2056. Intergenerational equity requires that the two runners have roughly equally difficult tasks. It seems to us that the task we have given the second runner (to cut the 2056 emissions rate in half between 2056 and 2106) will not be harder than the task of the first runner (to keep global emissions in 2056 at present levels)--provided that between now and 2056 the world invests in research and development to get ready. A vigorous effort can prepare the revolutionary technologies that will give the second half of the century a running start. Those options could include scrubbing CO2 directly from the air, carbon storage in minerals, nuclear fusion, nuclear thermal hydrogen, and artificial photosynthesis. Conceivably, one or more of these technologies may arrive in time to help the first runner, although, as we have argued, the world should not count on it.

As we look back from 2056, if global emissions of CO2 are indeed no larger than today's, what will have been accomplished? The world will have confronted energy production and energy efficiency at the consumer level, in all economic sectors and in economies at all levels of development. Buildings and lights and refrigerators, cars and trucks and planes, will be transformed. Transformed, also, will be the ways we use them.

The world will have a fossil-fuel energy system about as large as today's but one that is infused with modern controls and advanced materials and that is almost unrecognizably cleaner. There will be integrated production of power, fuels and heat; greatly reduced air and water pollution; and extensive carbon capture and storage. Alongside the fossil energy system will be a nonfossil energy system approximately as large. Extensive direct and indirect harvesting of renewable energy will have brought about the revitalization of rural areas and the reclamation of degraded lands. If nuclear power is playing a large role, strong international enforcement mechanisms will have come into being to control the spread of nuclear technology from energy to weapons. Economic growth will have been maintained; the poor and the rich will both be richer. And our descendants will not be forced to exhaust so much treasure, innovation and energy to ward off rising sea level, heat, hurricanes and drought.

Critically, a planetary consciousness will have grown. Humanity will have learned to address its collective destiny--and to share the planet.

39 percent

U.S. share of global carbon emissions in 1952

23 percent

The U.S. share of global emissions can be expected to continue to drop.

MANAGING THE CLIMATE PROBLEM

At the present rate of growth, emissions of carbon dioxide will double by 2056. Even if the world then takes action to level them off, the atmospheric concentration of the gas will be headed above 560 parts per million, double the preindustrial value--a level widely regarded as capable of triggering severe climate changes. But if the world flattens out emissions beginning now and later ramps them down, it should be able to keep concentration substantially below 560 ppm.

15 WAYS TO MAKE A WEDGE

An overall carbon strategy for the next haft a century produces seven wedges' worth of emissions reductions. Here are 15 technologies from which those seven can be chosen (taking care to avoid double-counting). Each of these measures, when phased in over 50 years, prevents the release of 25 billion tons of carbon. Leaving one wedge bank symbolizes that this list is by no means exhaustive.

END-USER EFFICIENCY AND CONSERVATION

  1. Increase fuel economy of two billion cars from 30 to 60 mpg[ 1]
  2. Drive two billion cars not 10,000 but 5,000 miles a year (at 30 mpg)
  3. Cut electricity use in homes, offices and stores by 25 percent

 

POWER GENERATION

  • 4. Raise efficiency at 1,600 large coal-fired plants from 40 to 60 percent[ 2]
  • 5. Replace 1,400 large coal-fired plants with gas-fired plants[ 3]

 

CARBON CAPTURE AND STORAGE (CCS)

  • 6. Install CCS at 800 large coal-fired power plants[ 4]
  • 7. Install CCS at coal plants that produce hydrogen for 1.5 billion vehicles[ 5]
  • 8. Install CCS at coal-to-syngas plants[ 6]

 

ALTERNATIVE ENERGY SOURCES

  • 9. Add twice today's nuclear output to displace coal
  • 10. Increase wind power 40-fold to displace coal[ 7]
  • 11. Increase solar power 700-fold to displace coal[ 7]
  • 12. Increase wind power 80-fold to make hydrogen for cars
  • 13. Drive two billion cars on ethanol, using one sixth of world cropland[ 8]

 

AGRICULTURE AND FORESTRY

  • 14. Stop all deforestation[ 9]
  • 15. Expand conservation tillage to 100 percent of cropland

Notes:

1. World fleet size in 2056 could well be two billion cars. Assume they average 10,000 miles a year.

2. "Large" is one-gigawatt (GW) capacity. Plants run 90 percent of the time.

3. Here and below, assume coal plants run 90 percent of the time at 50 percent efficiency. Present coal power output is equivalent to 800 such plants.

4. Assume 90 percent of CO2 is captured.

5. Assume a car (10,000 miles a year, 60 miles per gall on equivalent) requires 170 kilograms of hydrogen a year.

6. Assume 30 million barrels of synfuels a day, about a third of today's total oil production. Assume half of carbon originally in the coal is captured.

7. Assume wind and solar produce, on average, 30 percent of peak power. Thus replace 2,100 GW of 90-percent-time coal power with 2,100 GW (peak) wind or solar plus 1,400 GW of load-following coal power, for net displacement of 700 GW.

8. Assume 60-mpg cars, 10,000 miles a year, biomass yield of 15 tons a hectare, and negligible fossil-fuel inputs. World cropland is 1,500 million hectares.

9. Carbon emissions from deforestation are currently about two billion tons a year. Assume that by 2056 the rate falls by half in the business-as-usual projection and to zero in the flat path.

RICH WORLD, POOR WORLD

To keep global emissions constant, both developed nations (defined here as members of the Organization for Economic Cooperation and Development, or OEED) and developing nations will need to cut their emissions relative to what they would have been. The projections shown represent only one path the world could take; others are also plausible.

Share of CO2 emissions in 2002 

OECD
   North America and Mexico             28%
   Europe                               14%
   East Asia and Oceania                 8%

NON-OECD
   South/Southeast Asia                 10%
   Africa                                4%
   East Asia                            15%
   Former Soviet Bloc                   12%
   West Asia                             6%
   Central America and South America     4%

SOURCE: "GLOBAL, REGIONAL, AND NATIONAL FOSSIL FUEL CO2 EMISSIONS," BY G. MARLAND, T. A. BODEN AND R. J. ANDRES, IN TRENDS: A COMPENDIUM OF DATA ON GLOBAL CHANGE: CARBON DIOXIDE INFORMATION ANALYSIS CENTER, OAK RIDGE NATIONAL LABORATORY, 2006

OVERVIEW

• Humanity can emit only so much carbon dioxide into the atmosphere before the climate enters a state unknown in recent geologic history and goes haywire. Climate scientists typically see the risks growing rapidly as CO2 levels approach a doubling of their pre-18th-century value.

• To make the problem manageable, the required reduction in emissions can be broken down into "wedges"--an incremental reduction of a size that matches available technology.

MORE TO EXPLORE

Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies. S. Pacala and R. Socolow in Science, Vol. 305, pages 968-972; August 13, 2004.

The calculations behind the individual wedges are available at www.princeton.edu/~cmi

Energy statistics are available at www.eia.doe.gov, www.iea.org and www.bp.com; carbon emissions data can also be found at cdiac.esd.ornl.gov

MAP: RICH WORLD, POOR WORLD: Share of CO2 emissions in 2002

GRAPH: ANNUAL EMISSIONS: In between the two emissions paths is the "stabilization triangle." It represents the total emissions cut that climate-friendly technologies must achieve in the coming 50 years.

GRAPH: THE WEDGE CONCEPT: The stabilization triangle can be divided into seven "wedges," each a reduction of 25 billion tons of carbon emissions over 50 years. The wedge has proved to be a useful unit because its size and time frame match what specific technologies can achieve. Many combinations of technologies can fill the seven wedges.

GRAPH: CUMULATIVE AMOUNT: Each part per million of CO2 corresponds to a total of 2.1 billion tons of atmospheric carbon. Therefore, the 560-ppm level would mean about 1,200 billion tons, up from the current 800 billion tons. The difference of 400 billion tons actually allows for roughly 800 billion tons of emissions, because half the CO2 emitted into the atmosphere enters the planet's oceans and forests. The two concentration trajectories shown here match the two emissions paths above.

GRAPH: RICH WORLD, POOR WORLD: To hold global emissions flat, the OECD must emit less than today …

GRAPH: RICH WORLD, POOR WORLD: … to let non-OECD nations emit more as they develop economically

GRAPH: ONE PLAN FOR THE U.S.: U.S. share of emissions reductions could, in this Natural Resources Defense Council scenario, be achieved by efficiency gains, renewable energy and clean coal.

PHOTO (COLOR): Humanity faces a choice between two futures: doing nothing to curb emissions (which poses huge climate risks) and bringing them under control (which has costs but also benefits).

~~~~~~~~

By Robert H. Socolow and Stephen W. Pacala

ROBERT H. SOCOLOW and STEPHEN W. PACALA lead the Carbon Mitigation Initiative at Princeton University, where Socolow is a mechanical engineering professor and Pacala an ecology professor. The initiative is funded by BP and Ford. Socolow specializes in energy-efficient technology, global carbon management and carbon sequestration. He was co-editor (with John Harte) of Patient Earth, published in 1921 as one of the first college-level presentations of environmental studies. He is the recipient of the 2003 Leo Szilard Lectureship Award from the American Physical Society. Pacala investigates the interaction of the biosphere, atmosphere and hydrosphere on global scales, with an emphasis on the carbon cycle. He is director of the Princeton Environmental Institute.

Copyright of Scientific American© is the property of Scientific American Inc..

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Article No 2

A Climate Repair Manual.

This article introduces a series of articles focusing on ways to address global warming. According to the article, new reports surface continually on the perils of climate change, including threats to marine life, increases in wildfires, and even more virulent poison ivy. Implementing initiatives to stem global warming will prove very challenging. In the following articles, leading thinkers detail their ideas for deploying energy technologies to decarbonize the planet.

By STIX, GARY
Scientific American; Sep2006, Vol. 295 Issue 3, p46-49, 4p, 1 graph, 7c

INTRODUCTION
A Climate Repair Manual

Global warming is a reality. Innovation in energy technology and policy are sorely needed if we are to cope

Explorers attempted and mostly failed over the centuries to establish a pathway from the Atlantic to the Pacific through the icebound North, a quest often punctuated by starvation and scurvy. Yet within just 40 years, and maybe many fewer, an ascending thermometer will likely mean that the maritime dream of Sir Francis Drake and Captain James Cook will turn into an actual route of commerce that competes with the Panama Canal.

The term "glacial change" has taken on a meaning opposite to its common usage. Yet in reality, Arctic shipping lanes would count as one of the more benign effects of accelerated climate change. The repercussions of melting glaciers, disruptions in the Gulf Stream and record heat waves edge toward the apocalyptic: floods, pestilence, hurricanes, droughts-even itchier cases of poison ivy. Month after month, reports mount of the deleterious effects of rising carbon levels. One recent study chronicled threats to coral and other marine organisms, another a big upswing in major wildfires in the western U.S. that have resulted because of warming.

The debate on global warming is over. Present levels of carbon dioxide--nearing 400 parts per million (ppm) in the earth's atmosphere--are higher than they have been at any time in the past 650,000 years and could easily surpass 500 ppm by the year 2050 without radical intervention.

The earth requires greenhouse gases, including water vapor, carbon dioxide and methane, to prevent some of the heat from the received solar radiation from escaping back into space, thus keeping the planet hospitable for protozoa, Shetland ponies and Lindsay Lohan. But too much of a good thing--in particular, carbon dioxide from SUVs and local coal-fired utilities--is causing a steady uptick in the thermometer. Almost all of the 20 hottest years on record have occurred since the 1980s.

No one knows exactly what will happen if things are left unchecked--the exact date when a polar ice sheet will complete a phase change from solid to liquid cannot be foreseen with precision, which is why the Bush administration and warming-skeptical public-interest groups still carry on about the uncertainties of climate change. But no climatologist wants to test what will arise if carbon dioxide levels drift much higher than 500 ppm.

A League of Rations

PREVENTING the transformation of the earth's atmosphere from greenhouse to unconstrained hothouse represents arguably the most imposing scientific and technical challenge that humanity has ever faced. Sustained marshaling of cross-border engineering and political resources over the course of a century or more to check the rise of carbon emissions makes a moon mission or a Manhattan Project appear comparatively straightforward.

Climate change compels a massive restructuring of the world's energy economy. Worries over fossil-fuel supplies reach crisis proportions only when safeguarding the climate is taken into account. Even if oil production peaks soon--a debatable contention given Canada's oil sands, Venezuela's heavy oil and other reserves--coal and its derivatives could tide the earth over for more than a century. But fossil fuels, which account for 80 percent of the world's energy usage, become a liability if a global carbon budget has to be set.

Translation of scientific consensus on climate change into a consensus on what should be done about it carries the debate into the type of political minefield that has often undercut attempts at international governance since the League of Nations. The U.S. holds less than 5 percent of the world's population but produces nearly 25 percent of carbon emissions and has played the role of saboteur by failing to ratify the Kyoto Protocol and commit to reducing greenhouse gas emissions to 7 percent below 1990 levels.

Yet one of the main sticking points for the U.S.--the absence from that accord of a requirement that developing countries agree to firm emission limits-looms as even more of an obstacle as a successor agreement is contemplated to take effect when Kyoto expires in 2012. The torrid economic growth of China and India will elicit calls from industrial nations for restraints on emissions, which will again be met by even more adamant retorts that citizens of Shenzhen and Hyderabad should have the same opportunities to build their economies that those of Detroit and Frankfurt once did.

Kyoto may have been a necessary first step, if only because it lit up the pitted road that lies ahead. But stabilization of carbon emissions will require a more tangible blueprint for nurturing further economic growth while building a decarbonized energy infrastructure. An oil company's "Beyond Petroleum" slogans will not suffice.

Industry groups advocating nuclear power and clean coal have stepped forward to offer single-solution visions of clean energy. But too much devoted too early to any one technology could yield the wrong fix and derail momentum toward a sustainable agenda for decarbonization. Portfolio diversification underlies a plan laid out by Robert H. Socolow and Stephen W. Pacala in this single-topic edition of Scientific American. The two Princeton University professors describe how deployment of a basket of technologies and strategies can stabilize carbon emissions by midcentury.

Perhaps a solar cell breakthrough will usher in the photovoltaic age, allowing both a steel plant and a cell phone user to derive all needed watts from a single source. But if that does not happen--and it probably won't--many technologies (biofuels, solar, hydrogen and nuclear) will be required to achieve a low-carbon energy supply. All these approaches are profiled by leading experts in this special issue, as are more radical ideas, such as solar power plants in outer space and fusion generators, which may come into play should today's seers prove myopic 50 years hence.

No More Business as Usual

PLANNING in 50- or 100-year increments is perhaps an impossible dream. The slim hope for keeping atmospheric carbon below 500 ppm hinges on aggressive programs of energy efficiency instituted by national governments. To go beyond what climate specialists call the "business as usual" scenario, the U.S. must follow Europe and even some of its own state governments in instituting new policies that affix a price on carbon--whether in the form of a tax on emissions or in a cap-and-trade system (emission allowances that are capped in aggregate at a certain level and then traded in open markets). These steps can furnish the breathing space to establish the defense-scale research programs needed to cultivate fossil fuel alternatives. The current federal policy vacuum has prompted a group of eastern states to develop their own cap-and-trade program under the banner of the Regional Greenhouse Gas Initiative.

Fifty-year time frames are planning horizons for futurists, not pragmatic policymakers. Maybe a miraculous new energy technology will simultaneously solve our energy and climate problems during that time, but another scenario is at least as likely: a perceived failure of Kyoto or international bickering over climate questions could foster the burning of abundant coal for electricity and synthetic fuels for transportation, both without meaningful checks on carbon emissions.

A steady chorus of skeptics continues to cast doubt on the massive peer-reviewed scientific literature that forms the cornerstone for a consensus on global warming. "They call it pollution; we call it life," intones a Competitive Enterprise Institute advertisement on the merits of carbon dioxide. Uncertainties about the extent and pace of warming will undoubtedly persist. But the consequences of inaction could be worse than the feared economic damage that has bred overcaution. If we wait for an ice cap to vanish, it will simply be too late.

THE HEAT IS ON

A U.S. senator has called global warming the "greatest hoax" ever foisted on the American people. But despite persistently strident rhetoric, skeptics are having an ever harder time making their arguments: scientific support for warming continues to grow.

GREENHOUSE EFFECT

A prerequisite for life on earth, the greenhouse effect occurs when infrared radiation (heat) is retained within the atmosphere.

  1. Most solar energy reaching the earth is absorbed at the surface
  2. The warmed surface emits infrared radiation
  3. Like a blanket, atmospheric greenhouse gases absorb and reradiate the heat in all directions, including back to the earth
  4. Human activity has increased the amount of greenhouse gas in the atmosphere and thus the amount of heat returned to the surface. In consequence, global temperatures have risen

 

OVERVIEW

• New reports pile up each month about the perils of climate change, including threats to marine life, increases in wildfires, even more virulent poison ivy.

• Implementing initiatives to stem global warming will prove more of a challenge than the Manhattan Project.

• Leading thinkers detail their ideas in the articles that follow for deploying energy technologies to decarbonize the planet.

MORE TO EXPLORE

The End of Oil: On the Edge of a Perilous New World. Paul Roberts. Houghton Mifflin, 2004.

Kicking the Carbon Habit. William Sweet, Columbia University Press, 2006.

An Inconvenient Truth. Al Gore. Rodale, 2006.

GRAPH: This "hockey stick graph," from one of many studies showing a recent sharp increase in average temperatures, received criticism from warming skeptics, who questioned the underlying data. A report released in June by the National Research Council lends new credence to the sticklike trend line that traces an upward path of temperatures during the 20th century.

A line of SUVs symbolizes high per-capita U.S. energy consumption. But rising expectations pervade the developing world.

Many Chinese dream of trading a bicycle for a car.

Carbon emissions are heating the earth.

Then and now: Sunset Glacier in Alaska's Denali National Park, shown covering a mountainside in August 1939, had all but vanished 65 years later when photographed during the same month.

 

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By Gary Stix
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