Beijing officials had been signaling for many months that the country would move beyond its existing experimental markets for emissions rights in five cities and two provinces. These provincial programs cover a variety of sectors, including electricity generation, steel mills, cement factories, chemical complexes and other energy-intensive industries. But the trading volume has been very low, with just $400 million in credits traded on all the exchanges combined in the first four years through last June, according to monitoring funded by the World Bank.

The national market could face its own political interference that could hurt its chances of becoming a model for others. Electricity generation in China from coal and natural gas is dominated by five giant, state-controlled companies. A sixth runs the civilian nuclear power sector. Regardless of effectiveness or economics, the companies will probably do what Beijing wants them to do.

Beijing’s efforts also sometimes go awry. Just in the past few weeks, China has had to retreat temporarily from an ambitious plan to cut coal use in some parts of the country and rely more on natural gas, which produces fewer emissions.

“I don’t take the carbon market seriously,” said Derek Scissors, an economist who specializes in China with the American Enterprise Institute, a conservative think tank. “The first thing I would ask people is, ‘What markets in China do you think work really well?’ ”

The national emissions trading system being started will initially cover power companies that emit at least 26,000 tons a year of carbon — the equivalent of burning 10,000 tons of coal a year, and a threshold high enough to cover mainly larger users of coal and natural gas. Experimental markets in the seven original provinces and cities, which further cities and provinces are starting to replicate, will continue to cover the cement and steel industries as well as other manufacturing and industrial sectors. The goal is to eventually move them into the national market.

Beijing already regulates emissions from China’s electricity sector. On the other hand, having them trade with each other might help the central government figure out more rules to regulate trading in less regulated sectors, and also to identify which companies are the most efficient at reducing emissions.

The announcement comes as the United States under Mr. Trump prepares to eliminate an Obama-era plan for reducing America’s emissions. The United States has also removed climate change from its new national security strategy and has vowed to abandon the Paris agreement, under which nearly 200 nations pledged to curb greenhouse gases voluntarily and help poor countries cope with the consequences of climate change.