As evidence accumulates about the impact of fossil fuel use on the global climate, China’s surge into the front ranks of the world’s carbon emitters is an elephant in the room that we can no longer ignore. The numbers are sobering: the Chinese economy is growing by almost 10 percent annually, and its electricity demand by nearly 15 percent; roughly two big new coal-fired power plants are completed in China each week; new generating capacity equivalent to that of nearly the entire U.K. power grid was added last year alone; private car ownership is rising rapidly. In its latest projections, the International Energy Agency estimates that China will overtake the U.S. to become the world’s largest carbon emitter within five years (see “China’s Coal Future”).

Some invoke such data to argue that it is pointless for the United States to curtail its carbon emissions unless the Chinese begin to reduce theirs, which they show no sign of doing. Others say that argument is disingenuous–a convenient excuse to avoid painful choices at home–and that attempts to pressure China (and other developing countries) to reduce carbon emissions will simply be ignored if we fail to get our own house in order.

The truth is that the United States and China–between them responsible for 40 percent of global carbon emissions–have many good reasons to collaborate on emission reductions. But as U.S. policymakers consider their options for engaging the Chinese, they should keep two points in mind.

First, as relations with China move toward the center of U.S. foreign-policy concerns in the coming years, the global-warming problem–serious as it is–will be just one of several issues in which the U.S. has a major interest. Others include trade investment and industrial competition; the North Korean nuclear crisis and security in Northeast Asia; the developing contest for power and influence in energy-rich central Asia, the Middle East, and Africa; Chinese nuclear technology exports; and the longer-run prospect of China’s emergence as a global superpower and geostrategic rival. America’s interest in reducing China’s carbon emissions will not always be aligned with its other objectives. (Consider, for example, that a successful effort to slow the growth of China’s huge domestic coal industry will inevitably increase its already voracious appetite for oil and gas from the Middle East and elsewhere.) Managing this complex policy agenda will require not single-issue zealotry but, rather, hard choices among competing priorities, disciplined execution, and sustained statesmanship.

Second, notwithstanding growing environmental awareness in China, Beijing’s ability to act on the global-warming issue will be limited. This is not only because the legitimacy of the central government rests on its ability to continue delivering rapid economic growth, so that any perceived threat to that growth will meet with resistance. It is also because the fragmented, decentralized system of energy-related governance in China will hamper the government’s ability to meet any carbon mitigation commitments it does make. The fact that the Chinese state is authoritarian does not mean that it is internally coherent or effectively coördinated. China’s energy system is in its own way as politically complex, fractured, and unwieldy as our own. And we would be unwise to expect of the Chinese what we are unable or unwilling to ask of ourselves.

Richard Lester, an expert on energy technology and policy, is a professor of nuclear science and engineering at MIT and the founding director of its Industrial Performance Center.