Governments have set a goal of signing an agreement next year in Paris to curb emissions of climate-changing gases. Unlike the previous 1997 Kyoto Protocol, which exempted developing nations from emissions limits, this deal is supposed to cover every country. Progress has been stymied by conflict over how much of the burden poor countries should bear.
China, the biggest emitter, has promised to curb its output but with its economy slowing, and Beijing under pressure to generate jobs, has resisted binding limits.
Obama's proposal Monday to reduce emissions from the nation's power plants, many of which are coal-fired, would give American negotiators a fresh gesture to respond to demands for U.S. action, even though some environmentalists say the measure is too lax.
The proposed cuts are "not nearly enough," said Clare Perry, a campaigner for the London-based Environmental Investigation Agency, in an email. But they "should help bring China to the table," she said.
As the biggest emitter, China has to be on board for any global climate agreement to work, environmentalists say. Other big emitters in the developing world such as India, Brazil and South Africa are also crucial.
Like many developing countries, China's status has changed drastically since the 1997 agreement. It has grown into an export powerhouse and the second-largest economy, prompting American lawmakers who see it as a commercial rival to say any new treaty must cover China. Beijing says it is still too poor, with an income per person barely one-tenth the U.S. level, to take on the limits imposed on rich countries.
"Obama's plan to cut greenhouse gas may have some impact on China's decision-making," said Wang Ke, a professor at the School of Environment and Natural Resources at People's University in Beijing. "But China's goal will be based on its domestic needs in the transformation of its economy and handling smog."
The Chinese Ministry of the Environment did not respond to a request Tuesday for comment.
China accounted for 29 percent of global emissions in 2012, more than the United States and the 27-nation European Union combined, according to the Netherlands Environmental Assessment Agency.
While U.S. and European emissions decreased by 4 percent and 1.6 percent that year, China's rose by 3 percent. That came on top of 10 percent annual increases over the preceding decade.
Obama's proposal calls for reducing carbon dioxide emissions from U.S. power plants by 30 percent from 2005 levels by 2030.
Power plants are America's largest source of greenhouse gases, accounting for 38 percent of annual emissions. Plants have already reduced carbon emissions nearly 13 percent since 2005, meaning they are about halfway to meeting the administration's goal.
"This is to be welcomed and may refocus global attention on the challenge of climate change," said Shyam Saran, a diplomat who was India's chief climate negotiator in 2008-10.
Scientists say far larger cuts are required to avoid drastic environmental change.
Emissions must drop by 40-70 percent by 2050 to keep the global temperature rise below the 2-degree C (3.6-degree F) cap set in U.N. climate talks, according to a report in April by the Intergovernmental Panel on Climate Change.
Instead, emissions are rising. The IPCC said that global emissions increased by 2.2 percent a year between 2000 and 2010, outpacing growth in previous decades to reach "unprecedented levels."
Some group's fear Obama's plan will accelerate those trends.
Chandra Bhushan, deputy director general of the Delhi-based Center for Science and Environment, said the U.S. proposal is so lacking in ambition it might spur less action overall.
Other countries "will conclude that if the biggest economy in the world can do only this much, then why should we do more?" he said.
Chinese negotiators argue rich countries that account for most of the historical output of carbon dioxide since the start of the Industrial Revolution in the 18th century should bear the burden of cuts. China's CO2 output of 7.1 tons per person in 2012 was less than half the U.S. level of 16.4 tons. But China's emissions are rising so fast that its total historical output is forecast to match that of the United States by the end of this decade.
Beijing has taken some steps that made a dent in its voracious appetite for coal and oil such as promoting use of hydro and wind power to curb reliance on imported energy.
In the latest global talks, though, China has resisted giving up its status as a developing country.
At a meeting in November in Warsaw, China and India clashed with Western governments, demanding that rich countries continue to operate under stricter conditions than developing economies. In an attempt to keep talks on track, negotiators agreed to require only more vague "contributions" rather than "commitments."
AP researcher Yu Bing in Beijing and AP Writer Katy Daigle in New Delhi contributed.