Thomas Donlan of Barron’s demonstrates less excitement than climate alarmists about President Trump’s decision to withdraw the United States from the Paris climate agreement.

The United Nations has been constructing frameworks for global cooperation on climate change since 1979. Each step has turned out to be a way of saying, “Choke the U.S. and other developed nations, while letting the Third World use fossil fuels to catch up.”

The Paris agreement is the latest in a series of U.N. productions offering forceful declarations of principles lacking teeth. But the U.N. apparently understands what Will Rogers was talking about when he said that diplomacy is “the art of saying ‘nice doggie’ until you can find a rock.”

Be sure that the sponsors and promoters of the Paris agreement have their eyes on many rocks, which they will throw against the modern economy as soon as they can, against the internal combustion engine, against fossil fuels, and even against the most powerful noncarbon source of energy, nuclear power.

Trump is unimpressed by climate-change diplomats saying “nice doggie.” He is pointing toward the exit from the Paris agreement. We could complain that his withdrawal is largely symbolic, since the terms of the agreement state that no signatory may begin to withdraw from it for three years, and the withdrawal process will consume another year. But we prefer to remember that the whole agreement is voluntary, and the president is simply volunteering to ignore it.

Meanwhile, a peculiar paradox arises: To make progress toward its share of the agreed reduction, the U.S. need do nothing except let the market work, because the market is already following price signals to switch the U.S. energy economy from coal to natural gas.

Climate change isn’t just an environmental issue; it is primarily an economic problem. The real question in the debate is whether the solution lies in markets or politics. Looking at the history of international economic agreements, we should prefer to rely on markets.