March 03, 2008
"Dangerous Assumptions" FAQ
The Significance of the Nature Piece
What is the significance of "Dangerous Assumptions"?
"Dangerous Assumptions" argues that the United Nations Intergovernmental Panel on Climate Change has significantly underestimated the amount of emissions reductions required to stabilize carbon emissions at levels currently deemed acceptable in the policy debate. The technological challenge is at least twice as large as the world has come to believe. Policy makers would be wise, including those advancing climate policy proposals in Congress to carefully examine the scenarios that they use to see if in fact they also significantly underestimate the technology challenge.
Who are Roger Pielke, Jr., Tom Wigley, and Chris Green?
Pielke is a professor of environmental studies at University of Colorado, Boulder. Wigley is Senior Scientist at the National Center for Atmospheric Research, Climate and Global Dynamics Division, and Christopher Green is professor of economics at McGill University's Global Environmental and Climate Change Center. The three men are all highly respected experts and scientists in their fields.
What does it mean to "stabilize carbon dioxide"?
The dominant thinking among climate experts is that to stabilize the amount of carbon in the atmosphere we must dramatically reduce the amount of carbon emitted over the coming century. Some experts have said that the reduction in annual emissions must be as great as 100%; others, including the IPCC, suggest that the total is as much as 80% by mid-century.
What's the difference between the United Nations emissions scenarios and what Pielke et al. found?
Pielke et al. found that "two thirds or more of all the energy efficiency improvements and decarbonization of energy supply required to stabilize greenhouse gases is already built into the reference scenarios." This means that the IPCC, and most other analyses of climate policy, assume that a large portion of the decarbonization of the global energy supply will occur automatically, that is with out policy interventions. "If much of these advances occur spontaneously," Pielke et al. explain, "as suggested by the scenarios used by the IPCC, then the challenge of stabilization might be less complicated and costly. However, if most decarbonization does not occur automatically, then the challenge to stabilization could in fact be much larger than presented by the IPCC."
What does that mean?
It means that the United Nations' median scenario assumes that 77 percent of the emissions reductions required for stabilization will occur "spontaneously" -- without any change in policy.
Why won't that be the case? Isn't the "spontaneous" reduction of emissions what happened in developed countries like the U.S. and Europe?
The U.S. and Europe have decarbonized and become less energy intense. We produce more of our GDP with less energy. And the energy we use is cleaner -- natural gas, nuclear, renewables, and efficiency have reduced our dependence on coal. But this pattern of "decarbonization" has been reversed, mostly by fast-developing nations like China and India, which are still building their coal infrastructure.
But won't developing countries like China and India soon start to decarbonize?
It's not very likely. Pielke et al. write, "This is a process that is likely to continue for decades not only in China, but all over populous southeast and south Asia, and eventually in Africa, until well beyond the middle of the century. An analysis of China's carbon dioxide emissions estimated them to be increasing at a rate of between 11% and 13% per year for the period 2000-2010(12), which is far higher than that assumed by the SRES scenarios for the annual emissions growth rates from Asia (2.6%-4.8%)."
Credit: Pielke, et al., "Dangerous Assumptions," Nature, April 3, 2008
What are we looking at in the Pielke et al. graph above?
Each bar is a different United Nations IPCC scenario. The blue sections show the emissions reductions that the United Nations IPCC assumes will happen "spontaneously." The red sections shows what the U.N. says must happen through policy. The green bars represent stabilization at 500 ppm, and the dashed line shows stabilization at 450 ppm.
Did the United Nations IPCC make a mistake?
No. It appears that the IPCC knew that the global economy was recarbonizing, but chose to downplay this in its "The Summary for Policymakers," the document read by most reporters and political leaders.
Pielke et al. note that "Built-in emissions reductions were discussed briefly in Chapter 3, Working Group III of the recent report of IPCC(4), but are not reflected in its Summary for Policy Makers or elsewhere. Aside from a small group of specialists, the policy significance of starting with a frozen-technology baseline is not widely appreciated."
Credit: Dr. Martin Hoffert, Scientific American, September 2006.
Does this change the famous "stabilization wedges" theory of Princeton professors Rob Socolow and Steven Pacala?
In their 2004 article in Science, Socolow and Pacala estimate that it would take seven "stabilization wedges" to stabilize emissions by 2050. Each wedge represents 1 GtC of reduction every year until 2055. In a box (above) in the September 2006 special energy issue of Scientific American, NYU professor emeritus of physics, Dr. Martin Hoffert shows that the re-carbonization of the global economy demands 18, not seven, wedges.
Did Socolow and Pacala make a mistake?
In a 2006 chapter for a book, Socolow acknowledges that he is assuming that 11 ("virtual") emissions reduction wedges are built into his scenario. He writes, "Virtual wedges are already embedded in almost all baseline scenarios because decarbonization is a robust historical trend."
Socolow was challenged on this point by Dr. Martin Hoffert, Professor Emeritus of Physics at New York University. In a 2005 piece in the New Yorker (see appendix below), reporter Elizabeth Kolbert wrote of the disagreement between Hoffert and Pacala. Kolbert writes,
In the "business as usual" scenario that Socolow uses, it is assumed that decarbonization will continue. To assume this, however, is to ignore several emerging trends. Most of the growth in energy usage in the next few decades is due to occur in places like China and India, where supplies of coal far exceed those of oil or natural gas. (China, which has plans to build five hundred and sixty-two coal-fired plants by 2012, is expected to overtake the U.S. as the world's largest carbon emitter around 2025.) Meanwhile, global production of oil and gas is expected to start to decline -- according to some experts, in twenty or thirty years, and to others by the end of this decade. Hoffert predicts that the world will start to "recarbonize," a development that would make the task of stabilizing carbon dioxide that much more difficult. By his accounting, recarbonization will mean that as many as twelve wedges will be needed simply to keep CO2 emissions on the same upward trajectory they're on now. (Socolow readily acknowledges that there are plausible scenarios that would push up the number of wedges needed.)
What are the implications of this paper?
Pielke et al. conclude, "enormous advances in energy technology will be needed to stabilize atmospheric concentrations of carbon dioxide at levels that are currently considered acceptable... In the end, there is no question whether technological innovation is necessary -- it is. The question is, to what degree should policy focus explicitly on motivating such innovation?"
Breakthrough Institute believes that there are many implications. The first is that we should acknowledge that the current proposals in Congress to deal with global warming are based on scenarios that radically underestimate the technology gap. While we should take immediate action to curb emissions, we should also acknowledge that we do not have all the technologies or other strategies needed to reduce emissions. That means that we need a much larger national commitment to energy technology. Finally, we believe that Pielke et al. further emphasizes the importance of taking action to prepare and adapt to a warmer world as quickly as possible.
Aren't you worried that policymakers will look at this report and conclude that the challenge is so large that we can't do anything?
Breakthrough Institute believes that we can both prevent and prepare for global warming, but only if we first acknowledge the size and nature of the challenge. Breakthrough Institute agrees with Pielke et al when they conclude, "Climate policy will be much better informed with a clear-eyed view of the size of the technology challenge, rather than obscuring it through built-in assumptions of spontaneous decarbonization. Perhaps more importantly, however, if the IPCC has underestimated the future technological challenge of decarbonization then it will have compounded the challenge of stabilization by downplaying the scale of the additional investments needed in technological research, development and related activities."
Appendix A: Excepts from the 2005 New Yorker article on Dr. Robert Socolow and Dr. Martin Hoffert
"The Climate of Man," by Elizabeth Kolbert, March 2005.
In climate-science circles, a future in which current emissions trends continue, unchecked, is known as "business as usual," or B.A.U. A few years ago, Robert Socolow, a professor of engineering at Princeton, began to think about B.A.U. and what it implied for the fate of mankind. Socolow had recently become co-director of the Carbon Mitigation Initiative, a project funded by BP and Ford, but he still considered himself an outsider to the field of climate science. Talking to insiders, he was struck by the degree of their alarm. "I've been involved in a number of fields where there's a lay opinion and a scientific opinion," he told me when I went to talk to him shortly after returning from the Netherlands. "And, in most of the cases, it's the lay community that is more exercised, more anxious. If you take an extreme example, it would be nuclear power, where most of the people who work in nuclear science are relatively relaxed about very low levels of radiation. But, in the climate case, the experts -- the people who work with the climate models every day, the people who do ice cores -- they are more concerned. They're going out of their way to say, 'Wake up! This is not a good thing to be doing.' "
Socolow, who is sixty-seven, is a trim man with wire-rimmed glasses and gray, vaguely Einsteinian hair. Although by training he is a theoretical physicist -- he did his doctoral research on quarks -- he has spent most of his career working on problems of a more human scale, like how to prevent nuclear proliferation or construct buildings that don't leak heat. In the nineteen-seventies, Socolow helped design an energy-efficient housing development, in Twin Rivers, New Jersey. At another point, he developed a system -- never commercially viable -- to provide air-conditioning in the summer using ice created in the winter. When Socolow became co-director of the Carbon Mitigation Initiative, he decided that the first thing he needed to do was get a handle on the scale of the problem. He found that the existing literature on the subject offered almost too much information. In addition to B.A.U., a dozen or so alternative scenarios, known by code names like A1 and B1, had been devised; these all tended to jumble together in his mind, like so many Scrabble tiles. "I'm pretty quantitative, but I could not remember these graphs from one day to the next," he recalled. He decided to try to streamline the problem, mainly so that he could understand it.
There are two ways to measure carbon-dioxide emissions. One is to count the full weight of the CO2; the other, favored by the scientific community, is to count just the weight of the carbon. Using the latter measure, global emissions last year amounted to seven billion metric tons. (The United States contributed more than twenty per cent of the total, or 1.6 billion metric tons of carbon.) "Business as usual" yields several different estimates of future emissions: a mid-range projection is that carbon emissions will reach 10.5 billion metric tons a year by 2029, and fourteen billion tons a year by 2054. Holding emissions constant at today's levels means altering this trajectory so that fifty years from now seven billion of those fourteen billion tons of carbon aren't being poured into the atmosphere.
Stabilizing CO2 emissions, Socolow realized, would be a monumental undertaking, so he decided to break the problem down into more manageable blocks, which he called "stabilization wedges." For simplicity's sake, he defined a stabilization wedge as a step that would be sufficient to prevent a billion metric tons of carbon per year from being emitted by 2054. Along with a Princeton colleague, Stephen Pacala, he eventually came up with fifteen different wedges -- theoretically, at least eight more than would be necessary to stabilize emissions. These fall, very roughly, into three categories -- wedges that deal with energy demand, wedges that deal with energy supply, and wedges that deal with "capturing" CO2 and storing it somewhere other than the atmosphere. Last year, the two men published their findings in a paper in Science which received a great deal of attention. The paper was at once upbeat -- "Humanity already possesses the fundamental scientific, technical, and industrial know-how to solve the carbon and climate problem for the next half-century," it declared -- and deeply sobering. "There is no easy wedge" is how Socolow put it to me.
Consider wedge No. 11. This is the photovoltaic, or solar-power, wedge -- probably the most appealing of all the alternatives, at least in the abstract. Photovoltaic cells, which have been around for more than fifty years, are already in use in all sorts of small-scale applications and in some larger ones where the cost of connecting to the electrical grid is prohibitively high. The technology, once installed, is completely emissions-free, producing no waste products, not even water. Assuming that a thousand-megawatt coal-fired power plant produces about 1.5 million tons of carbon a year -- in the future, coal plants are expected to become more efficient -- to get a wedge out of photovoltaics would require enough cells to produce seven hundred thousand megawatts. Since sunshine is intermittent, two million megawatts of capacity is needed to produce that much power. This, it turns out, would require PV arrays covering a surface area of five million acres -- approximately the size of Connecticut.
Wedge No. 10 is wind electricity. The standard output of a wind turbine is two megawatts, so to get a wedge out of wind power would require at least a million turbines. Other wedges present different challenges, some technical, some social. Nuclear power produces no carbon dioxide; instead, it generates radioactive waste, with all the attendant problems of storage, disposal, and international policing. Currently, there are four hundred and forty-one nuclear power plants in the world; one wedge would require doubling their capacity. There are also two automobile wedges. The first requires that every car in the world be driven half as much as it is today. The second requires that it be twice as efficient. (Since 1987, the fuel efficiency of passenger vehicles in the U.S. has actually declined, by more than five per cent.)
Three of the possible options are based on a technology known as "carbon capture and storage," or C.C.S. As the name suggests, with C.C.S. carbon dioxide is "captured" at the source -- presumably a power plant or other large emitter. Then it is injected at very high pressure into geological formations, such as depleted oil fields, underground. No power plants actually use C.C.S. at this point, nor is it certain that CO2 injected underground will remain there permanently; the world's longest-running C.C.S. effort, maintained by the Norwegian oil company Statoil at a natural-gas field in the North Sea, has been operational for only eight years. One wedge of C.C.S. would require thirty-five hundred projects on the scale of Statoil's.
In a world like today's, where there is, for the most part, no direct cost to emitting CO2, none of Socolow's wedges are apt to be implemented; this is, of course, why they represent a departure from "business as usual." To alter the economics against carbon requires government intervention. Countries could set a strict limit on CO2, and then let emitters buy and sell carbon "credits." (In the United States, this same basic strategy has been used successfully with sulfur dioxide in order to curb acid rain.) Another alternative is to levy a tax on carbon. Both of these options have been extensively studied by economists; using their work, Socolow estimates that the cost of emitting carbon would have to rise to around a hundred dollars a ton to provide a sufficient incentive to adopt many of the options he has proposed. Assuming that the cost were passed on to consumers, a hundred dollars a ton would raise the price of a kilowatt-hour of coal-generated electricity by about two cents, which would add roughly fifteen dollars a month to the average American family's electricity bill. (In the U.S., more than fifty per cent of electricity is generated by coal.)
All of Socolow's calculations are based on the notion -- clearly hypothetical -- that steps to stabilize emissions will be taken immediately, or at least within the next few years. This assumption is key not only because we are constantly pumping more CO2 into the atmosphere but also because we are constantly building infrastructure that, in effect, guarantees that that much additional CO2 will be released in the future. In the U.S., the average new car gets about twenty miles to the gallon; if it is driven a hundred thousand miles, it will produce almost forty-three metric tons of carbon during its lifetime. A thousand-megawatt coal plant built today, meanwhile, is likely to last fifty years; if it is constructed without C.C.S. capability, it will emit some hundred million tons of carbon during its life. The overriding message of Socolow's wedges is that the longer we wait -- and the more infrastructure we build without regard to its impact on emissions -- the more daunting the task of keeping CO2 levels below five hundred parts per million will become. Indeed, even if we were to hold emissions steady for the next half century, Socolow's graphs show that much steeper cuts would be needed in the following half century to keep CO2 concentrations from exceeding that level. After a while, I asked Socolow whether he thought that stabilizing emissions was a politically feasible goal. He frowned.
"I'm always being asked, 'What can you say about the practicability of various targets?' " he told me. "I really think that's the wrong question. These things can all be done.
"What kind of issue is like this that we faced in the past?" he continued. "I think it's the kind of issue where something looked extremely difficult, and not worth it, and then people changed their minds. Take child labor. We decided we would not have child labor and goods would become more expensive. It's a changed preference system. Slavery also had some of those characteristics a hundred and fifty years ago. Some people thought it was wrong, and they made their arguments, and they didn't carry the day. And then something happened and all of a sudden it was wrong and we didn't do it anymore. And there were social costs to that. I suppose cotton was more expensive. We said, 'That's the trade-off; we don't want to do this anymore.' So we may look at this and say, 'We are tampering with the earth.' The earth is a twitchy system. It's clear from the record that it does things that we don't fully understand. And we're not going to understand them in the time period we have to make these decisions. We just know they're there. We may say, 'We just don't want to do this to ourselves.' If it's a problem like that, then asking whether it's practical or not is really not going to help very much. Whether it's practical depends on how much we give a damn."
Marty Hoffert is a professor of physics at New York University. He is big and bearish, with a wide face and silvery hair. Hoffert got his undergraduate degree in aeronautical engineering, and one of his first jobs, in the mid-nineteen-sixties, was helping to develop the U.S.'s antiballistic-missile system. Eventually, he decided that he wanted to work on something, in his words, "more productive." In this way, he became involved in climate research. Hoffert is primarily interested in finding new, carbon-free ways to generate energy. He calls himself a "technological optimist," and a lot of his ideas about electric power have a wouldn't-it-be-cool, Buck Rogers sound to them. On other topics, though, Hoffert is a killjoy.
"We have to face the quantitative nature of the challenge," he told me one day over lunch at the N.Y.U. faculty club. "Right now, we're going to just burn everything up; we're going to heat the atmosphere to the temperature it was in the Cretaceous, when there were crocodiles at the poles. And then everything will collapse."
Currently, the new technology that Hoffert is pushing is space-based solar power, or S.S.P. In theory, at least, S.S.P. involves launching into space satellites equipped with massive photovoltaic arrays. Once a satellite is in orbit, the array would unfold or, according to some plans, inflate. S.S.P. has two important advantages over conventional, land-based solar power. In the first place, there is more sunlight in space -- roughly eight times as much, per unit of area -- and, in the second, this sunlight is constant: satellites are not affected by clouds or by nightfall. The obstacles, meanwhile, are several. No full-scale test of S.S.P. has ever been conducted. (In the nineteen-seventies, NASA studied the idea of sending a photovoltaic array the size of Manhattan into space, but the project never, as it were, got off the ground.) Then, there is the expense of launching satellites. Finally, once the satellites are up, there is the difficulty of getting the energy down. Hoffert imagines solving this last problem by using microwave beams of the sort used by cell-phone towers, only much more tightly focussed. He believes, as he put it to me, that S.S.P. has a great deal of "long-term promise"; however, he is quick to point out that he is open to other ideas, like putting solar collectors on the moon, or using superconducting wires to transmit electricity with minimal energy loss, or generating wind power using turbines suspended in the jet stream. The important thing, he argues, is not which new technology will work but simply that some new technology be found. A few years ago, Hoffert published an influential paper in Science in which he argued that holding CO2 levels below five hundred parts per million would require a "Herculean" effort and probably could be accomplished only through "revolutionary" changes in energy production.
"The idea that we already possess the 'scientific, technical, and industrial know-how to solve the carbon problem' is true in the sense that, in 1939, the technical and scientific expertise to build nuclear weapons existed," he told me, quoting Socolow. "But it took the Manhattan Project to make it so."
Hoffert's primary disagreement with Socolow, which both men took pains to point out to me and also took pains to try to minimize, is over the future trajectory of CO2 emissions. For the past several decades, as the world has turned increasingly from coal to oil, natural gas, and nuclear power, emissions of CO2 per unit of energy have declined, a process known as "decarbonization." In the "business as usual" scenario that Socolow uses, it is assumed that decarbonization will continue. To assume this, however, is to ignore several emerging trends. Most of the growth in energy usage in the next few decades is due to occur in places like China and India, where supplies of coal far exceed those of oil or natural gas. (China, which has plans to build five hundred and sixty-two coal-fired plants by 2012, is expected to overtake the U.S. as the world's largest carbon emitter around 2025.) Meanwhile, global production of oil and gas is expected to start to decline -- according to some experts, in twenty or thirty years, and to others by the end of this decade. Hoffert predicts that the world will start to "recarbonize," a development that would make the task of stabilizing carbon dioxide that much more difficult. By his accounting, recarbonization will mean that as many as twelve wedges will be needed simply to keep CO2 emissions on the same upward trajectory they're on now. (Socolow readily acknowledges that there are plausible scenarios that would push up the number of wedges needed.) Hoffert told me that he thought the federal government should be budgeting between ten and twenty billion dollars a year for primary research into new energy sources. For comparison's sake, he pointed out that the "Star Wars" missile-defense program, which still hasn't yielded a workable system, has already cost the government nearly a hundred billion dollars.
A commonly heard argument against acting to curb global warming is that the options now available are inadequate. To his dismay, Hoffert often finds his work being cited in support of this argument, with which, he says, he vigorously disagrees. "I want to make it very clear," he told me at one point. "We have to start working immediately to implement those elements that we know how to implement and we need to start implementing these longer-term programs. Those are not opposing ideas."
"Let me say this," he said at another point. "I'm not sure we can solve the problem. I hope we can. I think we have a shot. I mean, it may be that we're not going to solve global warming, the earth is going to become an ecological disaster, and, you know, somebody will visit in a few hundred million years and find there were some intelligent beings who lived here for a while, but they just couldn't handle the transition from being hunter-gatherers to high technology. It's certainly possible. Carl Sagan had an equation -- the Drake equation -- for how many intelligent species there are in the galaxy. He figured it out by saying, How many stars are there, how many planets are there around these stars, what's the probability that life will evolve on a planet, what's the probability if you have life evolve of having intelligent species evolve, and, once that happens, what's the average lifetime of a technological civilization? And that last one is the most sensitive number. If the average lifetime is about a hundred years, then probably, in the whole galaxy of four hundred billion stars, there are only a few that have intelligent civilizations. If the lifetime is several million years, then the galaxy is teeming with intelligent life. It's sort of interesting to look at it that way. And we don't know. We could go either way."