Can China win the war on greenhouse gas emissions?.......

Anyone surprised that China, the world’s biggest greenhouse gas polluter, would agree to sharply curtail its emissions has not been paying attention.

China joined President Obama Wednesday in announcing the result of talks to jointly combat climate change. The announcement seemed a detour from China’s insistence that its continued economic growth is its only priority.

That stance, mirrored by second-most-populous India, has been at the heart of the stalemate in international negotiations over climate change. The United States has said it can’t make painful emissions cuts if developing nations continue to pollute; China and India have said they won’t jeopardize their economic growth just because Western nations have already fouled the atmosphere.

But while clinging to its tough negotiating stance, China also has been racing to develop alternative, nonpolluting energy sources.

China now holds two seemingly contradictory titles: It creates the most greenhouse gas pollution of any country, and it has developed more renewable energy than any country.

It is the largest producer of wind turbines, followed by the United States and Germany. It produces the most photovoltaic solar panels. It has shut down inefficient old manufacturing plants. And the agreement it announced Wednesday follows other ambitious — and largely successful — long-range planning goals to cut carbon.

Those goals started in 2006, when the central government became nervous about the consequences of the country’s fourfold expansion of energy consumption in the previous two decades. Those consequences included choking air pollution and degradation of the environment.

More to the point, the government began to see the regular protests over pollution in the cities and the countryside as a potential threat to its rule. And the political class — as well as their wives and children — are subjected equally to air pollution that in Beijing has soared to 20 times the World Health Organization safety standards.

The government in 2006 announced a 20 percent reduction in per-person energy use by 2010, and as that goal neared completion, it announced in 2009 a further 40 to 45 percent reduction in per-person carbon emissions by 2020.

The central government also has ordered a tenfold increase in nuclear power, a jump to 150 gigawatts from 3 gigawatts in wind power over 15 years, a tripling of solar power capacity to 70 gigawatts by 2017, and a massive expansion of hydro power. In the agreement announced Wednesday, China pledged to get 20 percent of its energy from nonpolluting sources by 2030, double its current proportion.

It is dabbling with several experimental cap-and-trade schemes, and has debated the possibility of adopting a game-changing carbon tax as a national strategy.

These are not paper tiger goals. China came very close to meeting its targets in 2010 by ordering the closure of factories and demanding higher auto fuel efficiency. China experts say that is one reason not to underestimate the country’s ability to meet ambitious goals: It can simply order compliance without running afoul of a recalcitrant Republican Congress.

This is not to suggest the map of China should be painted climate-friendly green. In a magnified version of President Obama’s “all of the above” energy strategy, China is pushing ahead with construction of coal plants at arate of one new plant every 10 days. It is eyeing what could be enormous shale gas fields.

Some of its ambitious conservation goals will be undermined by local industry officials who still are rewarded for exceeding production targets, not saving energy. And persistent corruption and manufacturing shortcomings may be obstacles; there are reports of fields of wind turbines standing idle because they do not work or aren’t connected to a grid.

But if China achieves only part of its potential, the result could be dramatic. With wind power alone, China theoretically could provide many multiples of the energy it now consumes.

The question, as Chris P. Nielson, executive director of the China Project at Harvard, put it in a New York Times op-ed last year, is whether China will win the battles but not the war on greenhouse gas emissions. It may be that the country’s economic growth has too much momentum, and the challenges of atmospheric change are too daunting, for anyone to stop the storm of climate change.