At the United Nations Climate Summit on Tuesday in New York, President Obama issued a strong challenge to the Beijing leadership. China and the United States “have a special responsibility to lead” on climate change, he said. “It’s what big nations have to do.” Obama said he had talked directly with Chinese Vice Premier Zhang Gaoli at the summit (President Xi Jinping did not attend) and urged the two countries to work together to cut global greenhouse gas emissions.

China is not likely to warm to the challenge. First, China has already committed itself to carbon-reduction targets that, at least on paper, are more ambitious than the US plan. Last month, China announced that it would launch a nationwide carbon cap-and-trade system, which, if it goes to plan, will be the largest carbon-reduction market in the world. China has the largest deployments of solar power in the world and has established significant new installations in wind and hydro power. The country is currently on track to reach its goal of reducing the CO2 emissions per unit of GDP output by 40–45 percent from 2005 levels by 2020. According to vice premier Zhang, China has already achieved a reduction of 28.8 percent.

Most of China’s ambitious climate policies are based on its “war on air pollution”—a series of policies launched by Beijing this past spring to combat the country’s growing pollution crisis. The “war” includes plans to reduce air pollution by 25 percent from 2012 levels by 2017. Most of the reductions will come from Beijing’s heat and power-generation sectors, including a 50 percent reduction in coal use in that city [PDF]. The cities of Hebei, Tianjin, Shandong, Chongqing and Shaanxi have also set hard targets for coal reduction.

Most notably, Zhang Gaoli said at the UN Climate Summit that China would announce new emissions reduction targets “as soon as possible,” including a target for “the peaking of total carbon dioxide emissions.” According to Professor Angel Hsu of Yale University, we can expect China to provide more specifics on its peak emissions target in its next Five Year Plan, due out in 2016. At that time, according to Hsu, “China will potentially announce an absolute cap in emission.” China has already announced peak emissions levels for “high carbon sectors” like cement and steel. The scientific community has long stated the importance of a total emissions cap. But so far, no other country has taken the important step of committing to one.

The second reason Obama’s challenge will fail to inspire Beijing is China’s commitment to the principle of common but differentiated responsibilities, which it has reiterated dozens of times. The principle is taken directly from the text of Article 3 of the United Nations Framework Convention on Climate Change (UNFCCC), which reads: “The Parties should protect the climate system for the benefit of present and future generations of humankind, on the basis of equity and in accordance with their common but differentiated responsibilities and respective capabilities. Accordingly, the developed country Parties should take the lead in combating climate change and the adverse effects thereof.”

China is not the only country to adopt this principle as the basis of its climate policy. Most developing countries, expressed through negotiating groups in the UN systems such as the G77 and China or the Like-Minded Developing Countries, or the Alliance of Small Island States or the Least Developed Countries, support that clause. It is this difference of opinion between developed and developing states that has stalled the UN climate talks since 2009.

If Obama is challenging China to set targets for emissions reductions, he is too late. China has already done that, and in many respects, its targets are more ambitious than those of the United States. To demand that China join the United States in co-leadership sounds good on the surface, but it dredges up a bitter debate that has divided the two countries since the UNFCCC was signed, in 1992.

The challenge that Obama should present to Beijing is to insist that China follow through on its commitments in a transparent and measurable way. Indeed, while China’s climate targets look good on paper, many of its policies have not been implemented satisfactorily, and others have backfired completely.

For example, the central mechanism of Beijing’s war on air pollution may clean the air in Beijing, but it will also create an increase to overall emissions. The Washington Post reported in September 2013, when a portion of the plan was first announced, that the initiative could amount to a “climate disaster.” “China is currently building a series of big new synthetic gas plants to turn coal into natural gas,” the Post observed, but “the synthetic gas plants themselves are extremely energy-intensive and could lead China to produce far more carbon-dioxide emissions in the long run—heating the planet even more drastically.”

Additionally, China has struggled with technological problems and connectivity issues in solar and wind energy, leaving massive renewable-energy installations inert, glistening in the sun, not generating a single watt of energy.

Corruption, non-compliance and poor data quality also threaten to derail China’s climate plans. Just one day after the summit in New York, the former head of China’s National Energy Administration, Liu Tienan, was charged with corruption and accepting nearly $6 million in bribes. Increasingly, there are stories of factories evading energy-efficiency targets. According to a recent report by the World Resources Institute, “Weak GHG data quality has become a major obstacle for China’s low-carbon development in the long-run.” The US government has questioned whether China has the “institutional capacity” and “political will” to publish accurate statistics.

China has come a long way, but it needs to go farther, especially as the pressure mounts. China has been the world’s largest emitter of GHGs since 2007. But China’s low per capita emissions—just one-seventh of US per capita emissions in 2007, and still just a little less than half of US emissions by 2013—have always given that country a back door in the climate blame game. Moreover, how can we blame China when nearly one-quarter of its emissions can be directly linked to products made for export—many of them to the United States? And, finally, how can we solely blame China when we also know that most of the emissions in the atmosphere now came from the United States and Europe and their respective industrial revolutions?

But China cannot hide behind these facts much longer. A shocking new report, released this month, shows that China’s per capita emissions are now higher than those of the European Union. This statistic alone could change China’s role in the international effort to reverse climate change.

China is indeed on the big stage now. But if Obama wants to present the United States as a reliable partner with China on climate change, he needs to recognize what China has already done. And Obama must realize that China’s biggest challenge is not making targets, but following through on them.

It’s important to get the diplomacy with China right. The United States and China are the world’s largest emitters and, as Obama says, the two must work together if there is to be any progress. Both countries are models for the rest of the world—if they don’t act, no one will. And if the two giants don’t change course, as The New York Times grimly warns, “the earth could warm by as much as 10 degrees Fahrenheit above the preindustrial level, which would likely be incompatible with human civilization in its current form.”