As the sun rises in mid-july over andrews Air Force Base near Washington, D.C., Secretary of State John Kerry climbs quickly – he’s positively bouncing – up the carpeted stairs of his blue-and-white government­issue 757. Kerry is heading to Beijing to talk with Chinese leaders about, among other things, one of President Obama’s top priorities in the waning days of his second term: the urgent need to reduce carbon pollution and limit the damage from climate change. But the rest of the world isn’t cutting Kerry any slack right now – there’s trouble with the elections in Afghanistan, rising conflict in the Middle East and upcoming negotiations with Iran on nuclear weapons. As he ducks into the plane, Kerry is already talking intensely on his cellphone, deeply wired into the global chaos. An aide shoulders his bags as well as a large black case that contains his acoustic guitar, which he takes with him everywhere and often plays late at night when he’s alone in his hotel room.

For nearly a decade, the U.S. and China, the two most powerful nations on the planet, have met every year to talk about how to run the world together. When the talks began in 2006, they focused on issues like currency-exchange rates, trade barriers and China’s never-ending disputes with Taiwan. In 2009, shortly after Obama’s inauguration, the U.S. pushed to add climate change to the mix, hoping that a better understanding between the U.S. and China would lead to a better deal at the Copenhagen climate summit that year. (It didn’t help – mistrust between the countries was a large part of the reason why the talks imploded.)

This year’s U.S. delegation includes many of the administration’s most influential climate hawks – Energy Secretary Ernest Moniz, top climate negotiator Todd Stern and John Podesta, counselor to Obama, who has become the administration’s de facto point man for climate policy. This is the diplomatic equivalent of a full-court press. In the past couple of years, Obama has made some important moves, including investing billions in clean energy, jacking up vehicle-efficiency standards and proposing rules to limit pollution from U.S. coal plants. But climate change is a global issue. Unless the West can persuade other countries to take climate action seriously, nothing any single nation does is going to matter much when it comes to solving the problem.

Except, that is, for China. The blunt truth is that what China decides to do in the next decade will likely determine whether or not mankind can halt – or at least ameliorate – global warming. The view among a number of prominent climate scientists is that if China’s emissions peak around 2025, we may – just barely – have a shot at stabilizing the climate before all hell breaks loose. But the Chinese have resisted international pressure to curb their emissions. For years, they have used the argument that they are poor, the West is rich, and that the high levels of carbon in the atmosphere were caused by America’s and Europe’s 200-year-long fossil­fuel binge. Climate change is your problem, they argued – you deal with it. But that logic doesn’t hold anymore. China is set to become the largest economy in the world this year, and in 2006, it passed the U.S. as the planet’s largest carbon polluter. China now dumps 10 billion tons of CO₂ into the atmosphere every year. That number is expected to grow to 15 billion tons by 2030, dwarfing the pollution of the rest of the world. If that happens, then the chances that the world will cut carbon pollution quickly enough to avert dangerous climate change is, according to Kevin Anderson, deputy director of the Tyndall Centre for Climate Change Research in the U.K., “virtually zero.”

John Kerry knows this. He also knows that when the nations of the world gather in Paris next December to try to hammer out a global climate agreement, it may be the last best chance to address this problem before the Years of Living Dangerously begin. Like other climate negotiations held under the banner of the United Nations Framework Convention on Climate Change, the Paris meeting is likely to be warped by 25-year-old grudges and a profound sense of distrust. “But right now, Paris is the only game we have,” one member of the State Department’s climate team told me. “If it fails, there is no Plan B.”

In Beijing, one of Kerry’s goals will be to find out all he can about China’s strategy for Paris – what kind of commitment the Chinese might make, how sincere they are, what tactics they will use. But for Kerry, this is anything but a straightforward conversation, because it’s twisted up in the shadow play of U.S.-China relations, which are marked by suspicion, paranoia and saber rattling on both sides as the U.S. adjusts to China’s rising power in the world. “What we are living through now is the end of 500 years of Western predominance,” historian Niall Ferguson has written. The issue is not whether China will challenge America’s dominance, but when and how.

Secretary of State Kerry met with China’s Preisent Xi in Beijin in July. (Photo: © Jim Bourg/Reuters/Corbis)

Shortly before takeoff, Kerry wanders down the aisle to chat. He talks idly about his July 4th celebration and the recent storm damages to his house on Nantucket. But when asked about his expectations for the Beijing summit, he looks grave: “Frankly, we’re not sure where this is all going.” He remembers what happened in Kyoto, Japan, in 1997, when the U.S. was mocked for signing an agreement that the Senate would never ratify, and in Copenhagen in 2009, when Obama arrived at a conference that was supposed to save the world but ended up being gridlocked by squabbles over money and emissions targets. Kerry is determined not to let that happen again.

After 25 years of failed climate negotiations, it’s easy to be cynical about the upcoming talks in Paris. But there are at least three factors that make a meaningful agreement next year possible.

The first is that climate change is no longer a hypothetical problem – it’s happening in real time all around us. Droughts, floods, more destructive storms, weird weather of all sorts – just look out your window. In the latest reports from the Intergovernmental Panel on Climate Change, the world’s top scientists called the fact that the Earth is warming “unequivocal” and stated that humans are the cause of it. Without dramatic action, the planet could warm up as much as 4 degrees Celsius (7.2 F) by the end of the century, which would be catastrophic. As Kerry said of a report last September, “The response must be all hands on deck. It’s not about one country making a demand of another. It’s the science itself demanding action from all of us.”

The second factor is that until now, the biggest obstacle to an international agreement to reduce carbon pollution has been the United States. But that’s starting to change. Thanks to Obama’s recent crackdown on pollution, as well as the boom in cheap natural gas, which has displaced dirty coal, carbon emissions in the U.S. are on the decline. “What the president has done is very important,” says Robert Stavins, director of the Harvard Project on Climate Agreements. “It allows the U.S. to look at other countries and say, ‘Hey, what are you doing?'”

The final reason for hope, paradoxically, is China’s relentless demand for energy. China is in the midst of a profound economic and social transformation, trying to reinvent itself from an economy based on selling cheap goods overseas to an economy based on selling quality consumer goods at home, while keeping growth rates high and cutting dependence on fossil fuels. Energy demand is expected to double by 2030, and at that pace, there is not enough oil, coal and gas in the world to keep their economy humming. So China’s ongoing energy security depends on the nation developing alternative energy sources in a big way. “We need more of everything,” says Peggy Liu, a sustainability leader who works across China. “Wind, solar, a modernized grid. We need to leapfrog over the past and into a clean-energy future.”

China’s leaders are also waking up to the fact that recent decades of hypergrowth, most of it fired by coal, have exacted a steep price. Air pollution in China’s big cities is among the worst in the world; one recent report found that poor air quality contributed to 1.2 million premature deaths in 2010. As Hank Paulson, former Secretary of the Treasury and longtime China observer, has put it, “What is another point of GDP worth, if dirty air is killing people?” Earlier this year, a riot broke out in Zhongtai, a town in eastern China, when protests against a new waste incinerator turned violent, leaving police vehicles torched and at least 39 people injured; in southern China, protests erupted over the construction of a coal-fired power plant. Similar clashes are increasingly frequent in China as pollution-related illnesses rise.

And it’s not just the air that’s a problem in China. More than 20 percent of the country’s farmland is polluted. Sixty percent of its groundwater supply is unfit for human consumption. Rivers are industrial sewers. Last year, 16,000 swollen and rotting dead pigs were found dumped in the Huangpu River near Shanghai.

What looks to be the impacts of climate change are starting to register too. Droughts have become longer and more frequent, forcing China to import ever-increasing amounts of staples like wheat and soy. By one count, 28,000 rivers in China have vanished. China’s southern provinces have the opposite problem: devastating floods as a result of intense rainfall. In addition, much of the coastline, including cities like Shanghai, are highly vulnerable to sea-level rise.

Chinese leaders know this trajectory is unsustainable – economically and politically. Earlier this year, Premier Li Keqiang “declared war” on pollution. Party leaders in China now routinely talk about the importance of “rebalancing the economy” and creating an “ecological civilization.” China Daily, the Communist Party house organ, regularly runs stories about air pollution and toxic waste. While I was in Beijing, I asked U.S. Ambassador to China Max Baucus why the Chinese were now willing to talk so openly about environmental issues. “The fragility of their government,” he said bluntly. “They will have a social revolt on their hands if they don’t come up with a way of dealing with this.”

Pollution from coal plants has helped make China the larges carbon-emitter on the planet. (Photo: © Imaginechina/Corbis)

So a big push for clean energy makes a lot of sense. In fact, you could easily argue that China has already done far more than the U.S. to transform its energy supply: Including hydropower, renewables now make up 20 percent of the energy mix (compared to 13 percent in the U.S.), a share targeted to double by 2030. China is the largest producer of wind and solar power on the planet. In 2013, nearly 60 percent of new-power generation was renewable. They also have 28 new nuclear plants under construction, more than any other country. Policywise, Chinese leaders have also been innovative. In the U.S., neither a carbon tax nor a cap-and-trade system to put a price on carbon pollution is under serious consideration; in contrast, China’s carbon-trading program, which includes more than 2,000 pollution sources, is the second-largest trading system in the world (after the EU’s). “If China is successful in using market forces to cap carbon and transform its economy, that may be the best shot we have to limit climate change,” says Dan Dudek, vice president of the Environmental Defense Fund.

The problem for China, in a word, is coal: About 70 percent of the country’s electrical power comes from burning dirty rocks. The Chinese consumed nearly 4 billion tons in 2012, almost as much as the rest of the world combined. Like the oil industry in the U.S., the coal industry has enormous sway in China, making it all the more difficult to kick the habit. But as the rising power of the 21st century, China is under enormous political pressure to behave responsibly, lest it be seen as a pariah like Russia. “The choices that Chinese leaders make in the next decade will be absolutely pivotal to solving the climate crisis,” says former Vice President Al Gore. And for China’s economic and social stability, the consequences couldn’t be higher. “Politically, it’s very difficult to be fingered as the one most responsible for a looming catastrophe,” Gore continues. Or, as Harvard’s Stavins says, “If it’s your century, you don’t obstruct – you lead.”

In the decade or so after 9/11, when U.S. foreign policy revolved around hunting down and killing Islamic terrorists, we didn’t make China a priority. Then in 2011, the Obama administration announced an “Asia pivot” in U.S. foreign policy to counter China’s rising influence. Among other things, the U.S. increased its military presence and surveillance missions in the region, stoking suspicion in China that one of the goals of U.S. foreign policy is to “contain” China – both economically and militarily (if it were, the U.S. was certainly not going to admit it).

China’s response only seemed to play into our fears. China had been investing in new long-range missiles, upgrading its navy, and began using its new muscle­ to claim disputed territory in the South China Sea. China has been playing more subtle games, too: blocking access to Google and The New York Times, and having hackers raid computers at a number of U.S. corporations, stealing trade secrets. Foreign-policy journals openly speculate about the possibility of war with China, a suggestion that U.S. officials dismiss as absurd. “If there is a war between the U.S. and China,” argues Cheng Li, director of the China program at the Brookings Institution, “it will not be over economics or security, it will be because of misjudgment and misunderstanding.”

Of course, even the most rabid warmongers realize that a war between the U.S. and China would be disastrous. That’s one reason why leaders on both sides are looking for common ground – and two of the biggest shared interests are climate and energy. “In a relationship fraught with tension, these are places where we can do business,” says Obama’s adviser Podesta.

On the flight to Beijing, there is a lot of talk about what that common ground between the U.S. and China might look like. Granted, climate catastrophe is bad for everyone. But what leverage does the U.S. really have over China? On a practical level, the Chinese would like access to American technology. (“The deal here is that the U.S. will let you buy lots of energy equipment at exorbitant prices,” jokes one journalist on the flight.) But the Chinese also understand that, given the GOP-held Congress, Obama doesn’t have the power to make any big future commitments to cut carbon pollution – and so why should they?

On a more human level, there’s also a lot of nervousness about China’s notorious difficulty as a negotiating partner. “China has a very top-down culture – you have to speak to people right at the top,” one of Kerry’s top advisers tells me. “And they are very motivated on climate, due to air-pollution issues. But it’s hard to get China to do hard things, in part because, unlike other Asian countries, doing things for the greater good is not a big motivation for them.”

The mismatch between the urgency of taking action and the self-destructive diddling of diplomacy is frightening to witness. A few weeks before heading to China with Kerry, I attended a UNFCCC climate conference in Bonn, Germany. The two-week-long meeting, one of several designed to begin mapping out an agreement for Paris next year, was held in the gray, bureaucratic-feeling Maritim Hotel near the banks of the Rhine and attended by nearly 2,000 delegates from more than 180 countries. But neither John Kerry nor Todd Stern was anywhere to be found; the U.S. delegation was headed by Trigg Talley, an affable white-haired man who is one of Stern’s deputies. If Bonn was a preview of how things will go next year in Paris, then you can kiss human civilization goodbye. Because nothing will get done. And if it appears that something might get done, you can be sure that somebody – most likely the Saudis, who are infamous for their ability to throw a monkey wrench into negotiations at the last minute – will do everything they can to derail it.

The sheer tedium of the discussions is difficult to capture, but let me try: During the plenary session on the final day, which was held in a conference room the size of a football field and was supposed to be where important breakthroughs were announced, I listened for hours to delegates from Singapore discuss the kind of formatting that should be used on the proposal and to delegates from Bolivia argue that bullet points should be used, not paragraph breaks. I never heard the words “carbon” or “greenhouse gas” in the entire session (although “adaptation” got tossed around a lot). The most memorable words were spoken by a delegate from South Africa: “We are sheep in need of herding.”

In Bonn, the stench of nearly 25 years of broken promises and failed agreements was palpable. The U.S. was viewed with particular skepticism and disdain, not just because the U.S. signed but then failed to ratify the Kyoto Protocol, but because until this administration, American presidents and congressional leaders never did anything intentional to substantively curb carbon pollution, despite the obvious impacts it would have on poorer nations. “You talk a lot, but you are not sincere,” one Turkish delegate sniffed to me. Trust in U.S. negotiators had been further undermined when documents made public by WikiLeaks and Edward Snowden revealed that the U.S. had been spying on negotiators from other countries before and during Copenhagen, trying to gain intelligence on their positions. The revelations were particularly damning given the good-faith nature of climate negotiations. “After almost 30 years of this kind of thing,” one longtime participant in these talks puts it, “what measure of trust can possibly exist? How do you strike a deal on issues that are central to your country’s survival with someone you think is out to screw you?”

Issues of trust aside, several things are immediately apparent to me in Bonn about the content and design of the agreement that is likely to emerge in Paris next year. One is that it is going to disappoint and anger a lot of people, particularly those who think the job of a climate treaty is to force big polluters to change their ways. The Paris agreement will largely be a “bottom up” treaty, in which each country will put forward a “contribution” for what each is willing to do to reduce carbon pollution. Those contributions will then be reviewed in the future – exactly how and by whom isn’t clear – to make sure each nation is keeping its promise. There will be no legally binding caps on emissions, no mandated “targets” that countries need to reach. In fact, it will not be a treaty at all (a treaty would need to be ratified by the U.S. Senate, which everyone knows will never happen). It will likely be an agreement “with legal force,” which means, basically, that some parts of the agreement might be legally binding in some countries.

However toothless this approach might seem, there is logic behind it. Since Kyoto, international climate efforts have largely failed because they were too prescriptive. Few nations were willing to bow to the demands of an international carbon police. And beyond that, there was no way to enforce carbon limits.

But even if the talks succeed in creating a sustainable basis for international cooperation, whatever emerges from Paris next year is extremely unlikely to put the world on a path that would limit warming to below 2 degrees Celsius (3.6 F), which was enshrined in the Copenhagen Accord as the threshold for dangerous climate change. For that to happen, says the Tyndall Centre’s Kevin Anderson, “global emissions from energy need to reach a peak by around 2020, and then rapidly reduce to zero by 2050 at the latest.” “I’m not giving up hope,” Kerry told me. “Physically, it’s possible. But politically, it will be very difficult.” Podesta is even more blunt. “If we wait until we have a binding international agreement that actually puts us on track for 2 C,” he says, “we’ll hit 2 C before we get an agreement. But we have to get started if we hope to get to the destination.”

The second revelation is that the Paris agreement is likely to be more about money than about carbon. That is not inappropriate: Climate change is, at its base, an environmental-justice issue, in which the rich nations of the world are inflicting damage on the poor ones. One question that has always haunted climate agreements is, how should the victims be compensated? In past U.N. agreements, developed countries have promised aid to poorer nations. But in translating these general commitments into hard numbers, says Elliot Diringer, a climate-policy expert at the Center for Climate and Energy Solutions, “the cash flows really have never been enough.”

In Paris, they will try again. The delivery vehicle of choice is called the Green Climate Fund, which was one of the few concrete accomplishments to come out of Copenhagen. The idea is simple: Rich countries pay into the fund, the fund’s 24-member board examines proposals from developing countries for clean-energy and climate-adaptation projects, and then it awards funds to those it finds worthy.

The Green Climate Fund was born in the closing days of the Copenhagen negotiations, when then-Secretary of State Hillary Clinton tried to lure China and other developing nations into a deal by promising that, in exchange for agreeing to a binding cap on carbon pollution as well as outside monitoring and verification of pollution rates, rich nations like the U.S. would pledge a combined $100 billion a year to help poor nations. Many negotiators thought it was a clever (or not so clever) ploy by the U.S. to make China take the fall for the collapse of the Copenhagen deal, since it was clear that China considers emissions data a state secret and would never allow outsiders to pore through the books. But regardless of the intentions, the deal fell apart. The $100 billion promise lingered, however, and was codified in later agreements. (Although $100 billion sounds like a lot, it’s a small part of the $1 trillion a year that will be necessary to transform the energy system.)

Right now, developed nations have a long way to go to live up to Clinton’s promise. The Green Climate Fund has taken four years to get up and running, and still nobody knows if it will primarily make loans or grants. So far, only Germany has come through with a meaningful pledge, offering $1 billion over the next nine years. Stern says the U.S. is putting “a lot of blood, sweat and tears” into getting the fund set up right, and that the $100 billion a year will come from a variety of sources, including private investment. But if the point of the fund is to demonstrate the commitment of rich nations to help the poor, it will need them to make real financial commitments. “Big new public funds are not viable,” says David Victor, a climate-policy expert at the University of California, San Diego. “This could be a train wreck of false expectations.”

In Bonn, the biggest question on many negotiator’s minds was, “Will China step up?” Despite the fact that China is the biggest carbon emitter on the planet, with the most dynamic economy in the world, the Chinese remain wedded to a 25-year-old idea that China is still a developing country, in the same category as, say, Uganda, and therefore not responsible for taking action. At least, not until the U.S. and the EU – which, with their cumulative emissions, have essentially caused the problem of global warming – take the first step. Among negotiators, China’s stance is widely viewed as a negotiating tactic to lower expectations for action and to allow it to play moral defender for other developing nations, some of whom fear that if China makes a big move, it will increase the pressure on them to do the same.

I got a preview of the kind of arguments U.S. negotiators will face when I bumped into Zou Ji, the deputy director general for the National Center for Climate Change Strategy and International Cooperation and a key member of the Chinese negotiating team, in the lobby of the Maritim Hotel. I asked him if the recent action by Obama to limit pollution from power plants and increase fuel-efficiency standards had changed the dynamics in the negotiations. “It is a good thing,” Ji told me. “But now, America says to us, ‘Your turn to step up.’ Well, we welcome what you have done, but we want to see more action from the U.S. first. It is very clear that Congress is a big constraint for you; Obama can only do what he can do.” Ji argues, accurately, that the U.S. is still the far richer country, and while China’s carbon emissions are enormous, if you break it down to per-capita emissions, the average American is responsible for dumping almost three times as much CO₂ into the atmosphere every year as the average Chinese.

I point out to him that this is true, but that cumulative emissions in China will soon dwarf those in the United States.

“China needs to do its part, but right now the U.S. still has huge potential to do more,” he says forcefully. “I have lived in the U.S., where everyone has a clothes dryer and an air conditioner and a big refrigerator and a big house and a big car. In the EU and Japan, they also live well, but people there only consume half the energy Americans do. You do have the capacity to live at the same standard and consume far less – if you choose.”

When Kerry’s plane lands in Beijing, we immediately jump into a line of SUVs and are whisked away to the Great Wall just north of the city for what one State Department staffer calls “a little cultural sightseeing.” When I visited the wall a few years ago, the air pollution was so bad, I could hardly see 15 feet in front of me; today, it’s clear enough to see the Xishan Mountains, which are 12 miles away at the western edge of the city. Kerry strolls along the wall with Chinese dignitaries, then we motorcade to the Marriott hotel in central Beijing, where the U.S. government has taken over two floors. Security is high: The entrance to the hotel is blocked, and armed agents are everywhere. The biggest concern seems to be Chinese spies; on an earlier trip to China, five members of Todd Stern’s team received spoof e-mails that contained a bot that could have given a hacker control of their computers, and shortly after I check into my hotel, I am told that I can assume my room is bugged and my e-mail is read. Across the street from the hotel is an Apple Store, Gucci, Hermès and, strangely, a coal-fired power plant with clouds and a blue sky painted on the sides, as if to disguise the dirty black rocks burning within.

The next morning, Chinese President Xi Jinping opens the talks at the Diaoyutai State Guesthouse, an elegant retreat in western Beijing. His address to 500 or so American and Chinese dignitaries isn’t exactly a rousing call to action on climate change. Instead, he talks about the importance of keeping the Chinese economy humming, declaring that China needs a peaceful and stable environment “more than ever.” Xi is a tough-looking guy with a Tony Soprano vibe, and his speech leaves no doubt that he sees China as the rising power. “It is natural that China and the U.S. may have different views, and even frictions, on certain issues,” he says. Then he adds, “Confrontation between China and the United States would definitely spell disaster for the two countries and for the wider world.” Xi only mentions climate change once, in a passing reference to it as a significant challenge that both nations face.

Protestors take to the streets to fight construction of a chemical factory in May 2013. (Photo: AFP/Getty Images)

Xi, who came to power in 2013, is “a very strong leader for China,” says Cheng Li of the Brookings Institution. Li contrasts him with other recent Chinese leaders, most of whom tended to be pale figures who dutifully rose through the ranks of the Communist Party. Xi, who is 61, rules with authority and efficiency. He grew up the son of a deputy prime minister and revolutionary who was known as an architect of China’s special economic zones, which were important drivers in the liberalization of China. As president, Xi has cracked down on corruption and is a fierce defender of Chinese interests in disputed territories like the South China Sea. He has also toughened up China’s internal security forces (China spends more on domestic security than it does on national defense). But U.S. officials who have had close contact with Xi are impressed by his directness. One White House staffer pointed to a recent agreement to reduce hydrofluorocarbons, a potent greenhouse gas, that Xi worked out with Obama last year. “Xi rolled the Chinese bureaucracy to get that done,” the staffer says. Kerry also sees him as an effective leader. “I had long conversations with Xi while I was chair of the Foreign Relations Committee,” he tells me. “The kind of action we’ve seen in China recently doesn’t happen without his personal commitment.”

When Kerry takes the podium after Xi steps down, he is conciliatory. He reassures Xi and other Chinese leaders in the room that the U.S. does not seek to “contain” China, and that it welcomes the emergence of “a peaceful, prosperous China that . . . chooses to play a responsible role in world affairs.” He, too, talks a lot about economic growth and how “the true measure of our success will not be just whether our countries grow, but how our countries grow.” Kerry continues, “Step by step, we are shifting our focus . . . to the inescapable reality of a clean-energy future.”

When Kerry travels to countries where the U.S. might be perceived to have the upper hand, he can be very blunt about the potential ravages of climate change. A few months ago, in a speech in Jakarta, Indonesia, he called it the “world’s most fearsome” weapon of mass destruction. But Kerry doesn’t say a word here about melting ice caps, rising seas or weapons of mass destruction. Instead, he talks about how clean energy is “the biggest market the world has ever seen.” He talks investment flows, technology sharing and pollution-free prosperity. “Our goal,” Podesta tells me, “is to create a virtuous circle in the Pacific, where they match our ambition, and then we match theirs.”

For the U.S., pushing for action is imperative: If China makes an aggressive move on carbon, it kills a favorite political talking point from climate deniers in Congress. “I can’t tell you how many meetings I’ve sat in where the subject of ‘What is China doing?’ comes up,” says Podesta. “For us, it’s important that we take that objection off the table.”

For the Chinese, beyond the obvious motivation to clean up the air, the question is what they want from the U.S. in return. As Kerry put it to me later, “The Chinese have a lot of stuff they want from us. We have natural gas. We have coal. We have clean-energy technology.” How this bargaining works out is the heart of the negotiations and gets into complex areas like protection of intellectual property rights. In the past, the Chinese simply wanted to buy our technology, copy it and manufacture it more cheaply than anyone else. “But that dynamic has changed,” says one Department of Energy official. “Now the deals are much more about joint ventures and shared investment.”

Later in the day, top members of the U.S. and China delegations meet in a conference room on the second floor for the Joint Session on Climate Change and Clean Energy. It is a stiffly formal scene, with Kerry, Podesta, Stern, U.S. Energy Secretary Moniz and science adviser John Holdren on one side of a long mahogany table, and Chinese leaders, including Vice Premier Wang Yang and lead climate negotiator Xie Zhenhua, on the other side. In this more intimate group, the Chinese are much blunter and more forthright about the risks of climate change. But it isn’t clear if this is because they feel more relaxed or because they are more willing to say what the U.S. wants to hear. State Councilor Yang, who opens the discussion, calls climate change “a common and grave challenge to mankind.” He talks about actions the Chinese government has taken to promote clean energy and efficiency, and he underscores China’s support of the UNFCCC climate negotiations. “We have also maintained close dialogue in consultation on [the U.S.’s and China’s] respective climate-change policies,” he says.

Kerry nods politely and then reads from prepared remarks: “Every one of us in this room is well aware that the climate crisis is one that respects no border. It’s transboundary. It affects the planet.”

The Chinese leaders listen carefully, just as the American team listened carefully to Yang’s remarks, attuned to nuances and gestures that gain trust or lose it, that show respect or haughtiness. And yet, I get the strong sense at this meeting, and at every other one I’ve attended, that 15 levels of chess are being played, that the motives and impulses of each side remain unknowable to the other, and that both sides are making calculations that will shape their careers, their economies and the future of the planet. And always the fear – expressed in the glint of an eye, a moment of hesitation – that each is being played. The Chinese worry that the U.S. won’t keep their word or has a secret plan to thwart their economic growth; the Americans worry that the Chinese are using shady data, and that they are only in it for the money.

Sometimes, the enormous gap between how the Chinese run their country and how the Americans run theirs reveals itself. One of those moments occurs on the second day of the talks in the Great Hall of the People in Tiananmen Square, which is China’s parliamentary chamber. Kerry and Yang appear at a press conference to bestow six “EcoPartnership” awards to American and Chinese organizations that are collaborating on clean-energy and climate solutions. In the context of the talks, it is a small-bore event, with a handful of dignitaries and some Chinese press.

But maybe because of this, Kerry’s remarks at the event are looser and less diplomatic than anything I’ve heard him say earlier. They are also more dangerous politically, because he talks about the one thing the Chinese leadership is most afraid of: the power of social activism. He describes how, in 1970, after 20 million Americans attended Earth Day rallies, public outrage led to the creation of the Environmental Protection Agency, as well as the passage of the Clean Air Act and, later, the Clean Water Act. “So I have seen the power of grassroots action, of local efforts becoming magnified and ultimately creating action at a larger, federal level,” Kerry says, his voice rising. “And I see that same kind of drive, that same kernel of innovation, and of demand for a difference, right here [in China], today.”

Kerry’s larger point is undoubtedly true – there is a rising consciousness of environmental issues in China, a sense that civilized societies don’t let their rivers catch fire. But as Kerry knows very well, there will be no organized demonstrations of millions of people marching on the streets in China, demanding change. If they tried, they would likely be tear-gassed or thrown in jail. Activism, such as it is in China, is either well-behaved and sanctioned by the state, or it is deemed reckless and dangerous and quickly shut down.

After his remarks at the Great Hall of the People, Kerry gets polite applause and then sits down to listen to a boilerplate speech from Yang. If anyone noticed that the secretary of state of the United States had just suggested that a populist movement in the People’s Republic of China could challenge the status quo, it wasn’t apparent.

One person who understands the dangers of social activism as well as anyone is Shuo Li, 27, a climate-policy officer for Greenpeace East Asia. Shortly after Kerry’s talk, I visited Li at Greenpeace’s office in Beijing. A year earlier, Greenpeace had published an investigation into the development of a coal-to-liquids plant in Inner Mongolia. Transforming coal into liquid fuels like diesel (or, in a similar process, natural gas) is expensive and, more importantly, an environmental disaster. Compared with typical refining processes, coal liquefaction produces 14 times the amount of carbon dioxide.

What’s interesting about Greenpeace’s investigation is that it targeted the owner of the plant, Shenhua Group, which is China’s biggest coal producer and a political powerhouse. (“Shenhua is the monster,” Li says.) In the U.S., enviros go after big companies all the time. But in China, this kind of action is unprecedented. As was its effectiveness. Li says the company called in Greenpeace, and Shenhua agreed to quit pumping out groundwater for use in the plant.

I ask Li if this is a sign that Chinese leaders are becoming more tolerant of environmental activism?

“Maybe a little,” Li says. He explains that unlike, say, publicly celebrating the Dalai Lama or arguing for the ethical treatment of the Uighur minority in China, it’s OK to raise questions about environmental problems. “But you have to do it the right way. You can go after local officials or individual power plants.” But, as he points out, there is no clear line between what is acceptable and what is not. “That is something everyone has to discover for themselves,” he says. He adds with a sly smile: “For the government, it is more effective that way.”

But Li knows he’s treading dangerous ground. In 2012, a 65-year-old former forestry official was threatened with five years in prison for publishing and distributing books that questioned the overdevelopment of Hainan Island in southern China. (He received a three-year suspended sentence and a fine.) Two years earlier, one of Beijing’s most respected science reporters, Fang Xuanchang, who earned a reputation for calling bullshit on many government-funded research projects, was brutally beaten on his way home from work. His assailants were never found. The message, as one journalist wrote in Foreign Policy, was clear: “Don’t go there, or you could be next.”

I asked about the rising number of protests around the country against industrial plants found to be dumping chemicals­ into rivers, or protesters throwing bricks at police to halt the construction of a new power plant. “Individual NIMBY actions are acceptable,” Li says. “But when you try to mobilize people on a larger scale, that is when you get in trouble.”

“Trouble, how?”

“You don’t even want to think about it,” Li answers, fear flashing in his eyes.

The rise of China, which was driven by the biggest and fastest industrial revolution the world has ever seen, was fueled almost entirely by coal. And its continued success – not to mention, in many ways, the fate of human civilization – depends on how quickly it can wean itself off this cheap, dirty, abundant fossil fuel. “The big question,” Moniz told me in Beijing, “is how fast they can bend down the curve of coal.”

“Bending down the curve of coal” is geek-speak for reducing dependency on coal. Because coal – by far the most carbon­intensive fossil fuel – will most likely be replaced by cleaner energy sources; in that case, the moment China’s coal consumption plateaus will also be the moment their greenhouse-gas pollution plateaus. And that could be the moment the world begins a transition toward a stable climate.

But the question is: When will that moment occur? In China, this question will not be answered by the invisible hand of the market but, ultimately, by the strong hand of President Xi and other party leaders. Xi and his advisers will make a complex economic and political calculation about how far they want to push clean energy – and whether they want to encourage a shift away from coal by, say, expanding the existing carbon-trading market, passing a straightforward tax on carbon, or simply issuing a dictum that caps the amount of coal the nation can consume. A few weeks before my conversation with Moniz, a respected Chinese academic had speculated that China would cap coal consumption by 2030. “That would be a big step in the right direction,” Gore told me. But as Gore well knows, unless that cap is followed by a radical and almost unimaginable global shift toward zero-carbon energy, it’s not a big enough step to avert climate chaos in the coming decades.

China has already taken a number of measures to move away from coal. It is reportedly closing down 50,000 small coal-fired furnaces and has essentially stopped building new coal plants in big eastern cities like Beijing and Shanghai. In 2020, burning coal will be banned in Beijing. But given the enormity of China’s coal addiction, these are just baby steps compared to what is needed.

And that’s one reason why the Chinese are very interested in natural gas. Natural gas has about half the carbon of coal, and burning it creates much less air pollution. China has the biggest shale-gas reserves in the world and would dearly like to unleash an American-style fracking boom (which is its own kind of environmental nightmare, of course). But the technology used to extract the gas from shale, which was invented in the U.S., is complex and not easy to replicate. In addition, shale gas in China is more deeply buried than in the U.S., and the soil is less porous, making the gas more difficult to extract. And thanks to methane leaks during fracking operations (methane, the principal component of natural gas, is a short-lived but potent greenhouse gas), the climate benefits of natural gas are questionable.

Imagining a fracked-out China is not pretty, but it might beat the alternative – making natural gas out of coal. The process is similar to the coal-to-liquids plant in Inner Mongolia that Greenpeace singled out, and like that process, it is both water- and carbon-intensive. China already has two coal-to-gas plants in operation, with as many as 48 more on the drawing board. Most of them are slated to be built in western China, far from population centers, where Chinese leaders are eager to spur development and provide jobs. But the cost to the atmosphere will be enormous. If all of these plants get built, they will collectively emit more than a billion tons of CO₂ each year – more than the entire nation of Germany emitted last year.

Moniz calls coal-to-gas plants in western China “a major issue” for Chinese and U.S. negotiators. “Burning natural gas may help them solve the problem of air pollution,” says Moniz. “But if they get it by manufacturing it from coal, they will be creating another, much larger problem.” And it’s one that impacts everyone on the planet.

The talks ended on a hot, humid afternoon in the Zhongnanhai compound in central Beijing, which houses offices for the Politburo’s most senior members. The compound, which is heavily guarded and closed to the public, is a reminder of China’s Imperial era, with a collection of traditional pavilions scattered around three lovely lakes. Kerry met with Chinese Premier Li Keqiang in the Purple Light Pavilion, a brightly painted pagoda-style building with small porcelain animals on the corners of the roof. Li has none of the bluster – or power – of President Xi, and after exchanging greetings and thank-yous, Kerry seemed eager to hit the road. They spoke in private for a half-hour, then Kerry climbed back into his SUV, and we motorcaded back to the Marriott for a final press conference.

Within minutes, the State Department was e-mailing a list of accomplishments to reporters, including joint U.S.-China demonstration projects on smart grids, technology to capture carbon from coal plants, and new initiatives on forestry and industrial boilers. It was all both important and unimportant, small steps in a long, long march. Later, Kerry would tell me he was impressed by what he’d seen from the Chinese on climate during the trip – “There was no backsliding,” he says. Others on the U.S. team described their sense that key Chinese leaders they’d met were “extraordinarily forward-leaning.”

But huge questions still loom about how far the U.S. and China and every other big polluter on the planet will go to cut emissions. For negotiators who are pushing for a tough agreement with meaningful reductions and clear financial accounting, the biggest fear is not that the U.S. and China won’t agree on key issues, but that they will agree on too much: “We are afraid that the U.S. and China will strike a bargain that makes them both comfortable, but does little or nothing to reduce the risk of climate change,” says Mohamed Adow, senior adviser for Christian Aid, a U.K.-based relief agency that works in many developing nations. “Then the rest of the world will have to decide if they want to go along, or fight for a stronger agreement.”

A few hours later, Kerry and his team jet off to Afghanistan. The world is a big, complicated place, and everyone – even the most committed climate warriors like Kerry – has a lot of other things to think about beyond how much carbon we are dumping into the atmosphere. And that, in a way, is always the problem: There is always something more urgent, more immediately catastrophic to seize the attention of policymakers – and in the coming years, many of the crises that will distract us from dealing with the realities of climate change will largely have been caused by climate change. Through all these short-term emergencies, the Earth will keep warming, the droughts will get worse, food will grow scarce, ice will vanish, the seas will rise, and starting around 2030, climate change will emerge from the background and eventually become the only thing we talk about. It will be the story of the century.

When we get to the Marriott, I walk across the sleek marble lobby with Podesta, who looks uncharacteristically somber. Just before we step into Kerry’s press conference – where he will again underscore the importance of taking action on climate change – I ask Podesta if two days of talks with the Chinese have made him feel more hopeful about Paris next year.

“Yes,” he says. “But it’s going to be a hard road.”