After high-level talks with the U.S., China has agreed to flesh out its earlier pledge to limit greenhouse-gas emissions through a set of new programs and policies.

Environmental groups welcomed the plans, which the U.S. and China announced jointly on Sept. 25, but a leading congressional critic said there was no assurance that China's promises would be fulfilled.

China’s climate-related moves, outlined in a joint statement by its President, Xi Jinping, and President Obama, include launching, in 2017, a system to cap carbon emissions and set up a system to trade emissions credits.

China also pledged that 50% of its new urban buildings would meet green building standards by 2020 and said it would contribute $3.1 billion to a bilateral fund aimed at helping developing countries to cut their greenhouse gases.

In addition, the White House said the U.S. and China “reached an important new understanding on the need to control financing for high-carbon projects internationally.”

Gene Karpinski, League of Conservation Voters president, said in a statement, “China’s commitment to limit and price the pollution fueling climate change, to help developing countries reduce their emissions and to significantly cut back its support for overseas coal plants is a big deal.”

The new cap-and-trade program would apply to industries such as power generation, steel, chemicals and nonferrous metals as well as building materials, including cement. “They’re the sectors that account for the vast majority of China’s emissions,” says Jake Schmidt, director of the Natural Resources Defense Council’s international program.

Schmidt says China has been developing pilot cap-and-trade programs, and there have been discussions about a 2017 start for a national system.

As Xi made the announcement, it should have an impact, Schmidt observes, adding, “As things work in China, when the boss’s boss speaks, that makes it official and makes it quite clear to those lower-level officials that this is for real and that we’re going to move forward with it.”

Bob Perciasepe, president of the Center for Climate and Energy Solutions and a former deputy Environmental Protection Agency administrator, pointed to a key detail in the cap-and-trade announcement, saying in a statement: “In setting a start date for its national emissions trading system, China sends a powerful signal that market-based strategies will play a critical role in the transition to a low-carbon future.”

Given the magnitude of China’s urban development despite the country’s recent economic slowdown, the green-buildings target could affect a substantial volume of new construction. “It’s an ambitious goal,” Schmidt says, noting that, in 2012, only 2% of new urban facilities were green.

China last December took a small step to help developing countries deal with greenhouse gases, pledging $20 million to the China South-South Cooperation Fund on Climate Change. Since the latest, much larger $3.1-billion commitment to that same fund was announced in a public appearance with President Obama, it has “a much larger meaning on the ground,” Schmidt adds.

China also agreed to bolster its policies and rules "with a view to strictly controlling public investment flowing into projects with high pollution and carbon emissions both domestically and internationally."

In 2013, the U.S. pledged to end government financing for new coal-fired powerplants except in the poorest nations.

In addition, China said it would carry out a “green dispatch” program in power generation, giving priority to renewable sources. It would continue to use fossil fuels but set sector guidelines to draw power first from the most efficient and cleanest generation sources.

But Senate Environment and Public Works Committee Chairman James Inhofe (R-Okla.) said China’s pledge to reduce emissions “has no guarantee of enforcement” and contends the Obama administration’s carbon-emission regulations will drive U.S. manufacturing jobs and investment to China.

Inhofe said, “This is a great deal for the Chinese, who are slated to continue increasing emissions with the potential of capping them years from now.”

The two presidents reaffirmed their November 2014 climate announcement in which China agreed to “peak” its carbon emissions by 2030, its first such limit.

For its part, the U.S. said it would seek to cut its greenhouse-gas emissions 26% to 28% below 2005 levels by 2025.