On Monday, the Obama administration announced the biggest step the U.S. has ever taken to curb emissions of greenhouse gases that cause global warming. The proposed rules, which would go into effect in one year, would reduce carbon emissions from power plants by 30% compared to 2005 levels by 2030. Obama has expressed hope that the rules would help the U.S. gain a leadership role on climate change leading up to an international climate summit in Paris next year.

Now, just one day later, it appears the administration's actions may already be motivating China, which is the biggest player in global climate talks, to act at home as well, by instituting a national cap on carbon emissions.

According to Reuters, He Jiankun, a university professor and deputy chairman of China's Advisory Committee on Climate Change, told a conference in Beijing on Tuesday that China will use a carbon cap when it forms and implements its next five-year plan that would guide government policies. It would also continue to use a metric known as carbon intensity, which measures the amount of emissions per unit of economic output.

"The government will use two ways to control CO2 emissions in the next five-year plan, by intensity and an absolute cap," Professor He said, according to Reuters.

However, it's unclear how much authority He has, since he is an advisor to the government, rather than a high-ranking official. Still, any sign of movement toward a national carbon cap in China is a big deal. (Reuters later updated their story to make clear that professor He was speaking in his capacity as an adviser and academic, not from the government's point of view.)

Ailun Yang, a senior associate who focuses on China at the World Resources Institute, a Washington think tank, told Mashable that Professor He is an influential advisor to the Chinese government on climate issues. "Whatever he said shouldn't be said to be equivalent to government statements," Yang said. "However his views are very important in the Chinese context."

As Reuters also reported, China's emissions have skyrocketed by 50% since 2005. In contrast, U.S. emissions have dropped 10% since 2005, largely due to the economic downturn and a switch from coal to natural gas for generating electricity in many states.

The possibility that China will cap its carbon, plus the U.S. announcement on Monday, could signal that the moribund international climate talks are in for a major revival.

The United States currently produces approximately 15 percent of global carbon emissions, second to China. Image: White House Council on Economic Advisors

China and the U.S. are the world's top two greenhouse gas emitters. China's economic expansion, powered largely by coal, is leading to growing emissions and increasingly foul and hazardous air quality in many Chinese cities.

For more than two decades of climate talks, China has resisted any absolute carbon emissions reductions, instead favoring measures that would be pegged to their economic development, Yang says.

"I think it's very positive to see that they are considering more formal and absolute targets," Yang said in an interview. "... Just the fact that they're considering an absolute form of an emissions target, that itself is a very positive signal."

However, the details of any climate plan matter a great deal, Yang said.

According to Brad Plumer at Vox, He Jiankun also signaled that China's emissions would continue to rise through 2030, which is inconsistent with what scientists have said is necessary in order to limit global warming below dangerous levels.

Those pesky details matter. Back in 2011, China introduced a cap on overall energy consumption. But that "cap" was more a set of guidelines than a binding limit. And, as a result, many of China's provinces continued to consume more energy than was allowed by the cap — in part because they have plenty of incentives to keep using coal and boost economic activity, Plumer wrote.

China's actions are critical to addressing a common refrain from those who oppose U.S. action to reduce emissions. As the argument goes, such reductions will only be overwhelmed by emissions abroad from countries like China and India. But, if China enacts a meaningful carbon cap, that argument may have less potency in Washington.

In a recent report from the White House Council on Economic Advisors, the administration laid out its case for seizing the initiative. "While some might suggest that the growing international share of GHG emissions means that U.S. reductions are too small to matter, in fact the opposite is true," the report says. "U.S. leadership is vital to the success of international negotiations to set meaningful reduction goals."