A second key to deep decarbonization brings up an inconvenient truth for the traditional Green movement: nuclear power is the world’s most abundant and scalable carbon-free energy source.76 Although renewable energy sources, particularly solar and wind, have become drastically cheaper, and their share of the world’s energy has more than tripled in the past five years, that share is still a paltry 1.5 percent, and there are limits on how high it can go.77 The wind is often becalmed, and the sun sets every night and may be clouded over. But people need energy around the clock, rain or shine. Batteries that could store and release large amounts of energy from renewables will help, but ones that could work on the scale of cities are years away. Also, wind and solar sprawl over vast acreage, defying the densification process that is friendliest to the environment. The energy analyst Robert Bryce estimates that simply keeping up with the world’s increase in energy use would require turning an area the size of Germany into wind farms every year.78 To satisfy the world’s needs with renewables by 2050 would require tiling windmills and solar panels over an area the size of the United States (including Alaska), plus Mexico, Central America, and the inhabited portion of Canada.79
Nuclear energy, in contrast, represents the ultimate in density, because, in a nuclear reaction, E = mc2: you get an immense amount of energy (proportional to the speed of light squared) from a small bit of mass. Mining the uranium for nuclear energy leaves a far smaller environmental scar than mining coal, oil, or gas, and the power plants themselves take up about one five-hundredth of the land needed by wind or solar.80 Nuclear energy is available around the clock, and it can be plugged into power grids that provide concentrated energy where it is needed. It has a lower carbon footprint than solar, hydro, and biomass, and it’s safer than them, too. The sixty years with nuclear power have seen thirty-one deaths in the 1986 Chernobyl disaster, the result of extraordinary Soviet-era bungling, together with a few thousand early deaths from cancer above the 100,000 natural cancer deaths in the exposed population.81 The other two famous accidents, at Three Mile Island in 1979 and Fukushima in 2011, killed no one. Yet vast numbers of people are killed day in, day out by the pollution from burning combustibles and by accidents in mining and transporting them, none of which make headlines. Compared with nuclear power, natural gas kills 38 times as many people per kilowatt-hour of electricity generated, biomass 63 times as many, petroleum 243 times as many, and coal 387 times as many—perhaps a million deaths a year.82
Nordhaus and Shellenberger summarize the calculations of an increasing number of climate scientists: “There is no credible path to reducing global carbon emissions without an enormous expansion of nuclear power. It is the only low carbon technology we have today with the demonstrated capability to generate large quantities of centrally generated electric power.”83 The Deep Carbonization Pathways Project, a consortium of research teams that have worked out roadmaps for countries to reduce their emissions enough to meet the 2°C target, estimates that the United States will have to get between 30 and 60 percent of its electricity from nuclear power by 2050 (1.5 to 3 times the current fraction), at the same time that it generates far more of that electricity to take over from fossil fuels in heating homes, powering vehicles, and producing steel, cement, and fertilizer.84 In one scenario, this would require quadrupling its nuclear capacity. Similar expansions would be necessary in China, Russia, and other countries.85
Unfortunately, the use of nuclear power has been shrinking just when it should be growing. In the United States, eleven nuclear reactors have recently been closed or are threatened with closure, which would cancel the entire carbon savings from the expanded use of solar and wind. Germany, which has relied on nuclear energy for much of its electricity, is shutting down its plants as well, increasing its carbon emissions from the coal-fired plants that replace them, and France and Japan may follow its lead.
Why are Western countries going the wrong way? Nuclear power presses a number of psychological buttons—fear of poisoning, ease of imagining catastrophes, distrust of the unfamiliar and the man-made—and the dread has been amplified by the traditional Green movement and its dubiously “progressive” supporters.86 One commentator blames global warming on the Doobie Brothers, Bonnie Raitt, and the other rock stars whose 1979 No Nukes concert and film galvanized baby-boomer sentiment against nuclear power. (Sample lyrics of the closing anthem: “Just give me the warm power of the sun . . . But won’t you take all your atomic poison power away.”)87 Some of the blame might go to Jane Fonda, Michael Douglas, and the producers of the 1979 disaster film The China Syndrome, so named because the melted-down nuclear reactor core would supposedly sink through the Earth’s crust all the way to China, after making “an area the size of Pennsylvania” uninhabitable. In a devilish coincidence, the Three Mile Island plant in central Pennsylvania suffered its partial meltdown two weeks after the movie’s release, creating widespread panic and making the very idea of nuclear power as radioactive as its uranium fuel.
It’s often said that with climate change, those who know the most are the most frightened, but with nuclear power, those who know the most are the least frightened.88 As with oil tankers, cars, planes, buildings, and factories (chapter 12), engineers have learned from the accidents and near-misses and have progressively squeezed more safety out of nuclear reactors, reducing the risks of accidents and contamination far below those of fossil fuels. The advantage even extends to radioactivity, which is a natural property of the fly ash and flue gases emitted by burning coal.
Still, nuclear power is expensive, mainly because it must clear crippling regulatory hurdles while its competitors have been given easy passage. Also, in the United States, nuclear power plants are now being built, after a lengthy hiatus, by private companies using idiosyncratic designs, so they have not climbed the engineer’s learning curve and settled on the best practices in design, fabrication, and construction. Sweden, France, and South Korea, in contrast, have built standardized reactors by the dozen and now enjoy cheap electricity with substantially lower carbon emissions. As Ivan Selin, former commissioner of the Nuclear Regulatory Commission, put it, “The French have two kinds of reactors and hundreds of kinds of cheese, whereas in the United States the figures are reversed.”89
For nuclear power to play a transformative role in decarbonization it will eventually have to leap past the second-generation technology of light-water reactors. (The “first generation” consisted of prototypes from the 1950s and early 1960s.) Soon to come on line are a few Generation III reactors, which evolved from the current designs with improvements in safety and efficiency but so far have been plagued by financial and construction snafus. Generation IV reactors comprise a half-dozen new designs which promise to make nuclear plants a mass-produced commodity rather than finicky limited editions.90 One type might be cranked out on an assembly line like jet engines, fitted into shipping containers, transported by rail, and installed on barges anchored offshore cities. This would allow them to clear the NIMBY hurdle, ride out storms or tsunamis, and be towed away at the end of their useful lives for decommissioning. Depending on the design, they could be buried and operated underground, cooled by inert gas or molten salt that needn’t be pressurized, refueled continuously with a stream of pebbles rather than shut down for the replacement of fuel rods, equipped to co-generate hydrogen (the cleanest of fuels), and designed to shut themselves off without power or human intervention if they overheat. Some would be fueled by relatively abundant thorium, and others by uranium extracted from seawater, from dismantled nuclear weapons (the ultimate beating of swords into plowshares), from the waste of existing reactors, or even from their own waste—the closest we will ever get to a perpetual-motion machine, capable of powering the world for thousands of years. Even nuclear fusion, long derided as the energy source that is “thirty years away and always will be,” really may be thirty years away (or less) this time.91
The benefits of advanced nuclear energy are incalculable.
Most climate change efforts call for policy reforms (such as carbon pricing) which remain contentious and will be hard to implement worldwide even in the rosiest scenarios. An energy source that is cheaper, denser, and cleaner than fossil fuels would sell itself, requiring no herculean political will or international cooperation.92 It would not just mitigate climate change but furnish manifold other gifts. People in the developing world could skip the middle rungs in the energy ladder, bringing their standard of living up to that of the West without choking on coal smoke. Affordable desalination of seawater, an energy-ravenous process, could irrigate farms, supply drinking water, and, by reducing the need for both surface water and hydro power, allow dams to be dismantled, restoring the flow of rivers to lakes and seas and revivifying entire ecosystems. The team that brings clean and abundant energy to the world will benefit humanity more than all of history’s saints, heroes, prophets, martyrs, and laureates combined.
Breakthroughs in energy may come from startups founded by idealistic inventors, from the skunk works of energy companies, or from the vanity projects of tech billionaires, especially if they have a diversified portfolio of safe bets and crazy moonshots.93 But research and development will also need a boost from governments, because these global public goods are too great a risk with too little reward for private companies. Governments must play a role because, as Brand points out, “infrastructure is one of the things we hire governments to handle, especially energy infrastructure, which requires no end of legislation, bonds, rights of way, regulations, subsidies, research, and public-private contracts with detailed oversight.”94 This includes a regulatory environment that is suited to 21st-century challenges rather than to 1970s-era technophobia and nuclear dread. Some fourth-generation nuclear technologies are shovel-ready, but are trussed in regulatory green tape and may never see the light of day, at least not in the United States.95 China, Russia, India, and Indonesia, which are hungry for energy, sick of smog, and free from American squeamishness and political gridlock, may take the lead.
Whoever does it, and whichever fuel they use, the success of deep decarbonization will hinge on technological progress. Why assume that the know-how of 2018 is the best the world can do? Decarbonization will need breakthroughs not just in nuclear power but on other technological frontiers: batteries to store the intermittent energy from renewables; Internet-like smart grids that distribute electricity from scattered sources to scattered users at scattered times; technologies that electrify and decarbonize industrial processes such as the production of cement, fertilizer, and steel; liquid biofuels for heavy trucks and planes that need dense, portable energy; and methods of capturing and storing CO2.
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The last of these is critical for a simple reason. Even if greenhouse gas emissions are halved by 2050 and zeroed by 2075, the world would still be on course for risky warming, because the CO2 already emitted will remain in the atmosphere for a very long time. It’s not enough to stop thickening the greenhouse; at some point we have to dismantle it.
The basic technology is more than a billion years old. Plants suck carbon out of the air as they use the energy in sunlight to combine CO2 with H2O and make sugars (like C6H12O6), cellulose (a chain of C6H10O5 units), and lignin (a chain of units like C10H14O4); the latter two make up most of the biomass in wood and stems. The obvious way to remove CO2 from the air, then, is to recruit as many carbon-hungry plants as we can to help us. We can do this by encouraging the transition from deforestation to reforestation and afforestation (planting new forests), by reversing tillage and wetland destruction, and by restoring coastal and marine habitats. And to reduce the amount of carbon that returns to the atmosphere when dead plants rot, we could encourage building with wood and other plant products, or cook the biomass into non-rotting charcoal and bury it as a soil amendment called biochar.96
Other ideas for carbon capture span a broad range of flakiness, at least by the standards of current technology. The more speculative end shades into geoengineering, and includes plans to disperse pulverized rock that takes up CO2 as it weathers, to add alkali to clouds or the oceans to dissolve more CO2 in water, and to fertilize the ocean with iron to accelerate photosynthesis by plankton.97 The more proven end consists of technologies that can scrub CO2 from the smokestacks of fossil fuel plants and pump it into nooks and crannies in the earth’s crust. (Skimming the sparse 400 parts per million directly from the atmosphere is theoretically possible but prohibitively inefficient, though that could change if nuclear power became cheap enough.) The technologies can be retrofitted into existing factories and power plants, and though they are themselves energy-hungry, they could slash carbon emissions from the vast energy infrastructure that is already in place (resulting in so-called clean coal). The technologies can also be fitted onto gasification plants that convert coal into liquid fuels, which may still be needed for planes and heavy trucks. The geophysicist Daniel Schrag points out that the gasification process already has to separate CO2 from the gas stream, so sequestering that CO2 to protect the atmosphere is a modest incremental expense, and it would yield liquid fuel with a smaller carbon footprint than that of petroleum.98 Better still, if the coal feedstock is supplemented with biomass (including grasses, agricultural waste, forest cuttings, municipal garbage, and perhaps someday genetically engineered plants or algae), it could be carbon-neutral. Best of all, if the feedstock consisted exclusively of biomass, it would be carbon-negative. The plants pull CO2 out of the atmosphere, and when their biomass is used for energy (via combustion, fermentation, or gasification), the carbon capture process keeps it out. The combination, sometimes called BECCS—bioenergy with carbon capture and storage—has been called climate change’s savior technology.99
Will any of this happen? The obstacles are unnerving; they include the world’s growing thirst for energy, the convenience of fossil fuels with their vast infrastructure, the denial of the problem by energy corporations and the political right, the hostility to technological solutions from traditional Greens and the climate justice left, and the tragedy of the carbon commons. For all that, preventing climate change is an idea whose time has come. One indication is a trio of headlines that appeared in Time magazine within a three-week span in 2015: “China Shows It’s Serious About Climate Change,” “Walmart, McDonald’s, and 79 Others Commit to Fight Global Warming,” and “Americans’ Denial of Climate Change Hits Record Low.” In the same season the New York Times reported, “Poll Finds Global Consensus on a Need to Tackle Climate Change.” In all but one of the forty countries surveyed (Pakistan), a majority of respondents were in favor of limiting greenhouse gas emissions, including 69 percent of the Americans.100
The global consensus is not just hot air. In December 2015, 195 countries signed a historic agreement that committed them to keeping the global temperature rise to “well below” 2°C (with a target of 1.5°C) and to setting aside $100 billion annually in climate mitigation financing for developing countries (which had been a sticking point in prior, unsuccessful attempts at a global consensus).101 In October 2016, 115 of the signatories ratified the agreement, putting it into force. Most of the signatories submitted detailed plans on how they would pursue these goals through 2025, and all promised to update their plans every five years with stepped-up efforts. Without this ratcheting, the current plans are inadequate: they would allow the world’s temperature to rise by 2.7°C, and would reduce the chance of a dangerous 4°C rise in 2100 by only 75 percent, which is still too close for comfort. But the public commitments, combined with contagious technological advances, could push the ratchet upward, in which case the Paris agreement would substantially reduce the likelihood of a 2°C rise and essentially eliminate the possibility of a 4°C rise.102
This game plan faced a setback in 2017 when Donald Trump, who had notoriously called climate change a Chinese hoax, announced that the United States would withdraw from the agreement. Even if the withdrawal takes place in November 2020 (the earliest possible da
te), the decarbonization driven by technology and economics will continue, and climate change policies will be advanced by cities, states, business and tech leaders, and the world’s other countries, which have declared the deal “irreversible” and may pressure the United States to keep its word by imposing carbon tariffs on American exports and other sanctions.103
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Even with fair winds and following seas, the effort needed to prevent climate change is immense, and we have no guarantee that the necessary transformations in technology and politics will be in place soon enough to slow down global warming before it causes extensive harm. This brings us to a last-ditch protective measure: lowering the world’s temperature by reducing the amount of solar radiation that reaches the lower atmosphere and Earth’s surface.104 A fleet of airplanes could spray a fine mist of sulfates, calcite, or nanoparticles into the stratosphere, spreading a thin veil that would reflect back just enough sunlight to prevent dangerous warming.105 This would mimic the effects of a volcanic eruption such as that of Mount Pinatubo in the Philippines in 1991, which spewed so much sulfur dioxide into the atmosphere that the planet cooled down by half a degree Celsius (about one degree Fahrenheit) for two years. Or a fleet of cloudships could spray a fine mist of seawater into the air. As the water evaporated, salt crystals would waft into the clouds and water vapor would condense around them, forming droplets that would whiten the clouds and reflect more sunlight back into space. These measures are relatively inexpensive, require no exotic new technologies, and could bring global temperatures down quickly. Other ideas for manipulating the atmosphere and oceans have been bruited about as well, though research on all of them is in its infancy.