One of the trickiest issues nations face in trying to reduce global greenhouse-gas emissions is the problem of fairness. The U.S., Western Europe, Japan, and a few other countries have a high standard of living, thanks largely to a long history of getting energy from burning cheap fossil fuels—coal, oil, and natural gas—which we now know are the main source of planet-warming carbon dioxide. But putting a lid on emissions makes energy more expensive, which means that developing countries wouldn't be able to improve their standard of living so easily. Why, they wonder, should they have to work harder than the already-developed countries did for their chance at the good life?
Back in 1997, the answer, enshrined in the Kyoto Protocol, was that they shouldn't. The document only assigned cutbacks to industrialized nations; that's one reason why American politicians rejected it. Now, though, China is a bigger greenhouse-gas emitter than the U.S. overall, and scientists have a better understanding of how deeply emissions need to be reduced globally to avoid overheating the planet. So the problem is more acute while the question of fairness is no less thorny.
But a new paper just published in Proceedings of the National Academy of Sciences may offer a way out—or at least the outlines of one. Instead of assigning limits based on a country's overall emissions, the focus should be on the highest emitters, no matter where they're located, argue lead author Shoibal Chakravarty, of Princeton University, and several colleagues. "Half of all emissions," Chakravarty says, "come from about 10 percent of the world's population." More of them are obviously in industrial countries, but, says Massimo Tavoni, another coauthor, "there are also people in China who drive Ferraris and fly a lot." So in this proposed new scheme, they write, "All of the world's high-CO2-emitting individuals are treated the same, regardless of where they live."
One way to do this is to put a cap on how much each person is allowed to emit, and calculate national targets from there. Say you want to guarantee that by 2030, emissions are no greater than they are today—about 30 billion metric tons of CO2 annually. Without some sort of cap, that figure is projected to rise to 43 billion by 2030.
But you can reach the goal if you assign a specific emissions limit to every individual in the world of 10.8 tons per person per year—and there are currently more than 1 billion people emitting above that level. "About a quarter of those," says Chakravarty, "live in the U.S., a quarter live in China, a quarter live in countries of the OECD [the Organisation for Economic Co-operation and Development, which is mostly European] and a quarter in the rest of the world."
"The average American," says Tavoni, "emits about 20 tons today, so that will be pretty tough. It tells you that a lot of Americans will have to reduce." In Europe, the average is closer to 10, so on average nobody will have to cut back, but in practice, anyone living above the limit will. (For the record, nobody keeps track of individual emissions, but it turns out, unsurprisingly, that high-income levels are correlated with high emissions. The scientists used World Bank data to estimate how many individuals in each country are above a certain emissions cap.) China's average is about four tons per person, and India's is about one—and the same rules apply. "So it turns out that even poor countries have to do something."
The authors also note that many people live entirely outside the fossil-fuel economy, in extreme poverty. "You want to bring these abjectly poor people up to the level of ordinary poverty," says Rob Socolow, another Princeton University coauthor, "to give them minimal electricity, access to motorized transport, even if it's only a motorbike, and some sort of cooking fuel that doesn't have to be gathered by hand." To do that, say the authors, the world could impose a carbon-emissions floor of, say one ton per year (which would lower the worldwide cap from 10.8 to about 10.3 tons). "There's an ideology out there," says Socolow, "that says, 'When you go to help the poorest people, don't hook them on fossil fuels.' This to me is outrageous. These are the people who deserve the cheapest solutions to their problems possible. Sure, sometimes it'll be biofuels or photovoltaic cells. But sometimes it will be kerosene, and that's just fine."
The authors don't pretend that their idea is the final word on dealing with the fairness problem—nor that it's the first. "At some point," says Chakravarty, "we found out others had thought about more or less similar schemes, although they differ in detail." But when more than 100 nations meet in Copenhagen next December at the Conference of the Parties to negotiate a successor agreement to the Kyoto Protocol, he says, ideas like these might just help break the fairness logjam.