Could a Trump presidency, in effect, ruin the global climate forever?

The answer is yes. The global, delicate effort to mitigate climate change already faced so many challenges, took so long to build, and came into being so desperately late. Trump, who has denied climate change is real and has an energy strategy based almost entirely on fossil fuels, could derail the effort entirely if he pulls the US out.

But it doesn’t have to be so—especially if key actors like China step up and take on responsibility for their actions, and for the world.

China to the fore

Let’s get this out of the way: China is the biggest emitter of greenhouse gases in the world. It’s responsible for about a fifth of all emissions, having taken over as the top polluter from the US in 2006. China burns so much coal that air pollution there has been estimated to kill up to 1 million people a year.

And back in 2009, when the world came together in Copenhagen and reached a (non-binding) agreement on cutting emissions multilaterally, China stood out for the wrong reasons: It was uncooperative and committed to its particular brand of economic growth—which meant emissions growth.

But in recent years the country has changed its stance and its ways. In 2015, China committed to cutting its emissions per unit of GDP by 60%-65% from 2005 levels. Total emissions there are still rising, but China has said it would work hard to reach peak total emissions by 2030.

It hasn’t committed to cuts in absolute terms, as many countries—most of the European Union, for example—have. But it has made a massive financial commitment to clean energy, becoming the biggest builder of new renewable infrastructure in 2014.

It’s also improved the efficiency with which energy is used. From 1990 to 2000, China cut its energy intensity—the energy used to produce each unit of GDP—by 5.9%, according to the International Energy Association, significantly more than the global average of 1.5%.

None of this is leadership, which to date has come mainly from Europe. But there are tentative signs that is shifting, too.

China’s chief climate negotiator, Xie Zhenhua, said that Trump should honor the US’s existing global commitments.

Ahead of the US elections, China’s chief climate negotiator, Xie Zhenhua, took the rare step of commenting on a foreign election to say that Trump should honor the US’s existing global commitments. A “wise” politician, Xie said, was one who conformed to global trends.

While that’s fairly oblique compared to many of the criticisms of Trump, it is an unusual example of China publicly weighing in on the climate policies of another country. Now that China has accepted the need for unified action, perhaps it is becoming more ready to push for it.

Meanwhile, it’s becoming clear that as far as China is concerned, climate change is central to the global agenda. And that commitment isn’t likely to change. China’s leadership style may be authoritarian, but it’s good for policy continuity.

America’s recently acquired mantle

There are two parts to every country’s climate policy.

The first is domestic: The efforts to cut emissions at home through policies like taxes on fuel and carbon or subsidies on renewable-energy infrastructure.

The other part is international. This can mean showing leadership in the intricate negotiations necessary to get dozens of countries to agree to policies requiring them to work together for a common good. Negotiators need the skills to find a way forward that feels fair to actors with incredibly different needs—and, potentially, then selling the policies to the people back home. In recent years, international leadership has also meant richer nations taking responsibility for past emissions—the industrial eras that saw their economies grow vast, fast—by agreeing to essentially fund poorer nations’ transition away from fossil fuels.

The US is important in both arenas.

Its greenhouse-gas emissions were the highest in the world until 10 years ago and are still second highest, so cutting at home has an impact globally. And as the world’s biggest economy, it is looked to as a leader. It’s hard, though not impossible, for global policy-makers to act effectively without American buy-in.

Until very recently, the US was not leading in global climate change policy. Far from it.

But until very recently, the US was not leading in global climate-change policy. Far from it. Al Gore, who ran in 2000 on a platform that included very clear climate policies, could have become the first president to make a meaningful impact globally. Instead, George W. Bush won and promptly pulled America out of the Kyoto Protocol, the hard-fought agreement between nations to work multilaterally towards protecting the climate.

Barack Obama was the first president to make serious efforts to tackle climate change through domestic policy. A hostile legislature derailed many of these endeavors, and Obama was criticized abroad for failing to provide more global leadership. It wasn’t until winning a second term, with less to lose domestically (US presidents can serve only two terms) and the climate menace clearer than ever, that Obama took bigger steps to make the US less dependent on oil. And it took until 2014 for him to announce a bilateral agreement with China, in which both countries agreed to cut emissions by a fixed amount for the first time.

America’s ability to cut emissions has always been hampered by the need to balance a climate-friendly policy with domestic needs like cheap gasoline. It has lagged far behind countries like Germany and others in Europe, but it was beginning to shoulder responsibility, provide vision, and set an example. That might not be the case for long.

What a Trump about-face could mean

Trump’s energy strategy calls for lifting constraints on domestic fossil-fuel production and reintroducing coal, the most polluting fuel, into the mix. He keeps promising “clean coal” technology, which is so expensive that, despite years of intensive R&D effort, it barely exists anywhere in the world.

He has also promised to cancel payment to United Nations climate programs, and use that money instead to “fix America’s water and environmental infrastructure.” Such spectacular abdication of responsibility for historical or future climate change would see the US instead focus on patching parts of a country damaged by some of the very things international climate strategy is seeking to mitigate, like pollution.

Putting Myron Ebell in charge of an agency with a climate remit is more dangerous than not having such an agency at all.

There is some hope Trump won’t actually enact all his campaign promises, perhaps by being persuaded out of them by the people he appoints. The likelihood of the latter is slim when it comes to climate. One of Trump’s first acts as president-elect was to appoint Myron Ebell to lead the transition team for the Environmental Protection Agency. Ebell denies that climate change is real. Putting him in charge of an agency with a climate remit is more dangerous than not having such an agency at all, as it will lend legitimacy to views that most scientists believe are laughable. The one ray of hope is that Ebell may find few allies in the House or the Senate because his views are so extreme.

Trump has also said he will pull out of the climate deal signed in Paris a year ago, which came into force on Nov. 4 and which the US has already ratified. That deal is the world’s current best hope for averting catastrophic climate change and most observers agree that even it does not yet go nearly far enough.

Trump’s promised policies would be a massive blow to the already-slim possibility of keeping global temperature from rising more than 2° C above pre-industrial averages—the threshold for preventing irreversible damage.

It isn’t clear whether Trump truly doesn’t believe in climate change, or just doesn’t care about the future. If the latter were the case, it wouldn’t be unusual. Voters want to be happy today, and can find it hard to understand the implications of policies that won’t be felt in their lifetimes.

That is the central issue to the whole history of climate change: politicians have neither the incentive to care nor, usually, a long enough mandate to make a difference.

How to hope

In the face of such terrifying prospects, turning to China for leadership might be a wild clutching at straws. The country has forged its own path to prosperity without much reference to the rest of the world and at massive cost to the environment.

But as China and others develop and Western economies stagnate, the bulk of emissions is shifting away from the developed world to newer economies. China could be a better model than the US for a nearby country like India, which is also guilty of massive, careless, carbon-intensive growth.

India can easily shirk responsibility if China is also shirking.

Since the two are regional rivals, a better way to express the relationship might be not as one of leadership, but of competition: India can easily shirk responsibility if China is also shirking, but if China is going green, Indians might be more easily persuaded to as well.

And in 2015, for the first time, global economic decoupled from from growing emissions. That was due, for the most part, to emissions cuts in two countries: China and the US.

In short, Donald Trump is assuming a frightening degree of power at what might be a tipping point in global climate negotiation. But he’s still one man, with a finite term both in office and on earth, contending with issues that are much larger than him, and trudging head-on against the flow of scientific knowledge, popular opinion, and—as Xie noted—global political trends.

Trump was elected on a platform of strength. Wisdom we might have to seek elsewhere.