by Carl Sagan
When greenhouse gases are added to the atmosphere, the Earth’s climate does not respond instantaneously. Instead it seems to take about a century for two-thirds of the total effect to be felt. Thus, even if we stopped all CO2 and other emissions tomorrow, the greenhouse effects would continue to build at least until the end of the next century. This is a powerful reason to mistrust the “wait-and-see” approach to the problem—it may be profoundly dangerous.
When there was an oil crisis in 1973–79, we raised taxes to reduce consumption, made cars smaller, and lowered the speed limits. Now that there’s a glut of petroleum we’ve lowered taxes, made cars larger, and raised the speed limits. There’s no hint of long-term thinking.
To prevent the greenhouse effect from increasing still further, the world must cut its dependence on fossil fuels by more than half. In the short term, while we’re stuck with fossil fuels, we can use them much more efficiently. With 5 percent of the world’s population, the United States uses nearly 25 percent of the world’s energy. Automobiles are responsible for almost a third of U.S. CO2 production. Your car emits more than its own weight in CO2 each year. Clearly, if we can get more miles per gallon of gasoline, we’ll be putting less carbon dioxide into the atmosphere. Nearly all experts agree that huge improvements in fuel efficiency are possible. Why are we—self-professed environmentalists—content with cars that get only 20 miles to the gallon? If we can drive at 40 miles per gallon, we’ll be injecting only half as much CO2 into the air; at 80 miles per gallon, only a quarter as much. This issue is typical of the emerging conflict between short-term maximizing of profits and long-term mitigation of environmental damage.
No one will buy the fuel-efficient cars, Detroit used to say; they’ll have to be smaller and so more dangerous; they won’t accelerate as quickly (although they certainly could go faster than the speed limits); and they’ll cost more. And it is true that in the middle 1990s, Americans have been increasingly driving gas-guzzling cars and trucks at high speeds—in part because petroleum is so cheap. So the American auto industry fought and more indirectly still fights meaningful change. In 1990, for example, after great pressure from Detroit, the Senate (narrowly) rejected a bill that would have required significant improvements in fuel efficiency in American automobiles, and in 1995–96 already-mandated fuel efficiencies in a number of states were relaxed.
But downsizing cars is not required, and there are ways of making even smaller cars safer—such as new shock-absorbing structures, components that crumble or bounce, composite construction, and air bags for all seats. Apart from young men in the throes of deep testosterone intoxication, how much do we lose in forgoing the ability to exceed the speed limit in a few seconds, compared with how much we gain? There are quick-accelerating gasoline-burning cars on the road today that get 50 or more miles per gallon. The cars might cost more to buy, but certainly would cost far less to fuel: According to one U.S. Government estimate, the added expense would be recouped in only three years. As far as the claim that no one will buy such cars, this underestimates the intelligence and environmental concern of the American people—and the power of advertising let loose in support of a worthy goal.
Speed limits are established, driving licenses mandated, and many other restrictions levied on the drivers of automobiles in order to save lives. Automobiles are recognized as potentially so dangerous that it is the obligation of the government to set some limits on how they’re manufactured, maintained, and driven. This is even more true once we recognize the seriousness of global warming. We’ve benefitted from our global civilization; can’t we modify our behavior slightly to preserve it?
The design of a new, safe, fast, fuel-efficient, clean, greenhouse-responsible class of autos will spur many new technologies, and make a great deal of money for those with a technological edge. The greatest danger for the American automobile industry is that if it resists too long, the necessary new technology will be provided (and patented) by foreign competition. Detroit has a particular and parochial motivation to develop new greenhouse-responsible cars: its survival. This is not a matter of ideology or political prejudice. It follows, I believe, directly from greenhouse warming.
The three big Detroit-based auto manufacturers—prodded and partly financed by the federal government—are sluggishly but collaboratively attempting to develop a car that will achieve 80 miles a gallon, or its equivalent for cars that run off something other than gasoline. If gasoline taxes were to rise, the pressures on automakers to build more fuel-efficient cars would increase.
Lately some attitudes have been changing. General Motors has been developing an electric automobile. “You must incorporate your environmental directions into your business,” advised Dennis Minano, the vice president of Corporate Affairs at GM in 1996. “Corporate America is beginning to see that it is clearly good for business.… There’s a more sophisticated market now. People will measure you as you take environmental initiatives and incorporate them to make your business successful. They’re saying, ‘We won’t call you green, but we’ll say you have low emissions, or a good recycling program. We’ll say you’re environmentally responsible.’ ” Rhetorically, at least this is something new. But I’m waiting for that affordable 80-miles-per-gallon GM sedan.
What is an electric car? You plug it in, charge its battery, and drive away. The best such autos, made of composites, achieve a few hundred miles per charge, and have passed standard crash tests. If they are to be environmentally sound, they will have to employ something other than massive lead-acid batteries—lead is a deadly poison. And of course the charge that makes an electric car go has to come from somewhere; if, say, it’s a coal-fired electric power plant, it has done nothing to mitigate global warming, whatever its contribution to reducing pollution of cities and highways.
Similar improvements can be introduced throughout the rest of the fossil-fuel economy: Coal-fired plants can be made much more efficient; large rotating industrial machinery can be designed for variable speeds; fluorescent rather than incandescent lamps can be made much more widespread. Innovations in many cases will in the long run save money and help us to extricate ourselves from a risky dependence on overseas oil. There are reasons to increase the efficiency with which we use our fuels wholly independent of our concern about global warming.
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But increasing the efficiency with which we extract energy from fossil fuels isn’t enough in the long run. As time goes on there will be more of us on Earth, and greater power demands. Can’t we find alternatives to fossil fuels, ways of generating energy that don’t produce greenhouse gases, that don’t warm the Earth? One such alternative is widely known—nuclear fission, releasing not chemical energy trapped in fossil fuels, but nuclear energy locked in the heart of matter. There are no nuclear autos or airplanes, but there are nuclear ships and there certainly are nuclear power plants. The cost of electricity from nuclear power is, under ideal circumstances, about the same as that from power plants that run off coal or oil, and these plants generate no greenhouse gases. None at all. Nevertheless …
As Three Mile Island and Chernobyl remind us, nuclear power plants can release dangerous radioactivity, or even melt down. They generate a witches’ brew of long-lived radioactive waste that must be disposed of. “Long-lived” means really long-lived: The half-lives of many of the radioisotopes are centuries to millennia long. If we want to bury this stuff, we have to be sure that it will not leach out and enter into the groundwater or otherwise surprise us—and not just over a period of years, but over periods of time much longer than we have been able in the past to plan for with confidence. Otherwise, we are saying to our descendants that the wastes we will to them are their burden, their lookout, their danger—because we couldn’t find a safer way to generate energy. (Indeed, this is just what we now do with fossil fuels.) And there’s one other problem: Most nuclear power plants use or generate uranium and plutonium that can be employed to manufacture nuclear weapons. They provide a continuing tempt
ation for rogue nations and terrorist groups.
If these issues of operational safety, radioactive waste disposal, and weapons diversion were solved, nuclear power plants might be the solution to the fossil fuel problem—or at least an important stopgap, a transitional technology until we find something better. But these conditions have not been satisfied with high confidence, and there does not seem to be a strong prospect that they will. Continuing violations of safety standards by the nuclear power industry, systematic cover-up of those violations, and failures of enforcement by the U.S. Nuclear Regulatory Commission (driven in part by budgetary restrictions) do not inspire confidence. The burden of proof is on the nuclear power industry. Some nations such as France and Japan have made a major conversion to nuclear energy, despite these worries. Meanwhile, other nations—Sweden, for example—that had previously authorized nuclear power have now decided to phase it out.
Because of widespread public uneasiness about nuclear energy, all U.S. orders for nuclear power plants placed after 1973 have been canceled, and no new plants have been ordered since 1978. Proposals for new storage or burial sites for radioactive wastes are routinely rejected by the communities involved. The witches’ brew accumulates.
There is another kind of nuclear power—not fission, where atomic nuclei are split apart, but fusion, where they are put together. In principle, fusion power plants might run off seawater—a virtually inexhaustible supply—generating no greenhouse gases, posing no dangers of radioactive waste, and wholly uninvolved with uranium and plutonium. But “in principle” doesn’t count. We’re in a hurry. With enormous efforts and very high technology, we are now perhaps at the point where a fusion reactor will barely generate a little more power than it uses up. The prospect for fusion power is a prospect of hypothetical, enormous, expensive, high-technology systems, which even their proponents do not imagine being available on a commercial scale for many decades. We do not have many decades. Early versions are likely to generate stupendous quantities of radioactive waste. And in any case, it’s hard to imagine such systems as the answer for the developing world.
What I’ve talked about in the last paragraph is hot fusion—so called for a good reason: You have to bring materials up to temperatures of millions of degrees or more, as in the interior of the Sun, to make fusion go. There have also been claims for something called cold fusion, which was first announced in 1989. The apparatus sits on a desk; you put in some kinds of hydrogen, some palladium metal, run an electric current, and, it is claimed, out comes more energy than you put in, as well as neutrons and other signs of nuclear reactions. If only this were true, it might be the ideal solution to global warming. Many scientific groups all over the world have looked into cold fusion. If there’s any merit to the claim, the rewards, of course, would be enormous. The overwhelming judgment of the community of physicists worldwide is that cold fusion is an illusion, a mélange of measurement errors, absence of proper control experiments, and a confusion of chemical with nuclear reactions. But there are a few groups of scientists in various nations that are continuing to look into cold fusion—the Japanese Government, for example, has supported such research at a low level—and each such claim should be evaluated on a case-by-case basis.
Maybe some subtle, ingenious new technology—wholly unforeseen at this moment—is just around the corner that will provide tomorrow’s energy. There have been surprises before. But it would be foolhardy to bet on it.
For many reasons, developing countries are particularly vulnerable to global warming. They are less able to adapt to new climates, adopt new crops, reforest, build seawalls, accommodate to drought and floods. At the same time they are especially dependent on fossil fuels. What is more natural than for China, say—with the world’s second largest coal reserves—to rely on fossil fuels during its exponential industrialization? And if emissaries from Japan, Western Europe, and the United States were to go to Beijing and ask for restraint in the burning of coal and oil, wouldn’t China point out that these nations did not exercise such restraint during their industrialization? (And anyway the 1992 Rio Framework Convention on Climate Change, ratified by 150 countries, calls for developed countries to pay the cost of limiting greenhouse gas emissions in developing countries.) Developing countries need an inexpensive, comparatively low-technology alternative to fossil fuels.
So if not fossil fuels, and not fission, and not fusion, and not some exotic new technologies, then what? In the administration of U.S. President Jimmy Carter, a solar-thermal converter was installed in the roof of the White House. Water would circulate and on sunny days in Washington, D.C., be heated by sunshine and make some contribution—perhaps 20 percent—to White House power needs, including, I suppose, Presidential showers. The more energy supplied directly by the Sun, the less energy that had to be drawn from the local electric power grid, and so the less coal and oil that needed to be spent to generate electricity for the electric power grid around the Potomac River. It didn’t provide most of the energy needed, it didn’t work much on cloudy days, but it was a hopeful sign of what was (and is) needed.
One of the first acts of the Presidency of Ronald Reagan was to rip the solar-thermal converter off the White House roof. It was somehow ideologically offensive. Of course it costs something to renovate the White House roof, and it costs something to buy the additional electricity needed every day. But those responsible evidently concluded that the cost was worth the benefit. What benefit? To whom?
At the same time, Federal support for alternatives to fossil fuels and nuclear power was steeply cut, by around 90 percent. Government subsidies (including huge tax breaks) for the fossil fuel and nuclear industries remained high through the Reagan/Bush years. The Persian Gulf War of 1991 can be included, I think, in that list of subsidies. While some technical progress in alternative energy sources was made during that time—little thanks to the U.S. Government—essentially we lost 12 years. Because of how fast greenhouse gases are building up in the atmosphere, and how long their effects last, we did not have 12 years to waste. Government support for alternative energy sources is finally increasing again, but very sparingly. I’m waiting for a President to reinstall a solar-energy converter in the White House roof.
In the late 1970s there was a federal tax credit for introducing solar-thermal heaters into homes. Even in mainly cloudy places, individual homeowners who took advantage of the tax break now have abundant hot water, for which they are not charged by the utility company. The initial investment was recouped in about five years. The Reagan Administration eliminated the tax credit.
There is a range of further alternative technologies. Heat from the Earth generates electricity in Italy, Idaho, and New Zealand. Seventy-five hundred turbines, turned by wind, are generating electricity in Altamont Pass, California, with the resulting electricity sold to the Pacific Gas and Electric Company. In Traverse City, Michigan, consumers are paying somewhat higher prices for wind turbine electrical power to avoid the environmental pollution of fossil fuel electrical power plants. Many other residents are on a waiting list to sign up. With allowance for environmental costs, wind-generated electricity is now cheaper than electricity generated by coal. All of U.S. electricity use, it is estimated, could be supplied by widely spaced turbines over the windiest 10 percent of the country—largely on ranch and agricultural lands. Moreover, fuel made from green plants (“biomass conversion”) might substitute for oil without increasing the greenhouse effect, because the plants take CO2 out of the air before they’re made into fuel.
But from many standpoints, it seems to me, we should be developing and supporting direct and indirect conversion of sunlight into electricity. Sunlight is inexhaustible and widely available (except in extremely cloudy places like upstate New York, where I live); has few moving parts, and needs minimal maintenance. And solar power generates neither greenhouse gases nor radioactive waste.
One solar technology is widely used: hydroelectric power plants. Water is evaporated by the heat of
the Sun, rains down on highlands, courses through rivers running downhill, runs into a dam, and there turns rotating machinery that generates electricity. But there are only so many swift rivers on our planet, and in many countries what is available is inadequate to supply their energy needs.
Solar-powered cars have already competed in long-distance races. Solar power could be used for generating hydrogen fuel from water; when burned, the hydrogen simply regenerates water. There’s a great deal of desert in the world that might be gainfully employed in an ecologically responsible way, for harvesting sunlight. Solar-electric or “photovoltaic” energy has been routinely used for decades to power spacecraft in the vicinity of the Earth and through the inner Solar System. Photons of light strike the cell’s surface and eject electrons, whose cumulative flow is a current of electricity. These are practical, extant technologies.
But when, if ever, will solar-electric or solar-thermal technology be competitive with fossil fuels in powering homes and offices? Modern estimates, including those by the Department of Energy, are that solar technology will catch up in the decade following 2001. This is soon enough to make a real difference.
Actually, the situation is much more favorable than this. When such cost comparisons are made, the accountants keep two sets of books—one for public consumption and the other revealing the true costs. The cost of crude oil in recent years has been about $20 a barrel. But U.S. military forces have been assigned to protect foreign sources of oil, and considerable foreign aid is granted to nations largely because of oil. Why should we pretend this isn’t part of the cost of oil? We abide ecologically disastrous petroleum spills (such as the Exxon Valdez) because of our appetite for oil. Why pretend this isn’t part of the cost of oil? If we add in these additional expenses, the estimated price becomes something like $80 a barrel. If we now add the environmental costs that using this oil levies on the local and global environments, the real price might be hundreds of dollars a barrel. And when protecting the oil motivates a war, as for example the one in the Persian Gulf, the cost becomes far higher, and not just in dollars.