In a year when climate change is moving from abstract theory to grimly tangible reality, a faint dot of hope may be on the horizon.

China, the world’s largest source of planet-warming carbon emissions, may have hit the peak it promised in the Paris climate accord well before its 2030 timetable. That’s the conclusion reached by scientists who looked at the country’s estimated carbon output between 2007 and 2016, as the country’s rapid industrialization slowed and its consumption of coal declined. The research is published in the journal Nature Geoscience.

“They are able to manage quite significant economic growth, but have been able to stabilize their emissions over the past few years,” said Dabo Guan, a professor of climate change economics at the University of East Anglia in Britain.

Guan and his colleagues estimate Chinese emissions of carbon dioxide and other greenhouse gases topped out in 2013 at about 9.5 billion tons. The numbers declined to about 9.2 billion tons in 2016, the last year of the study. And while other observers say there’s some fine print, every ton of CO2 that’s not released provides more breathing space in the global fight to hold global average temperatures at between 1.5 to 2 degrees Celsius (2.7 to 3.6 degrees F) over pre-industrial times.

“I wouldn’t call it a significant decline, but it’s stability,” Guan said.

After nearly three decades of rapid growth, China passed the United States to become the world’s largest source of carbon emissions in 2006. And with the Trump administration walking away from the Paris accord and trying to roll back its predecessors’ steps to meet that pact’s goals, what happens in China takes on outsized importance in the battle against climate change.

“If China doesn’t peak, there’s no hope,” said Jennifer Turner, who directs the China Environment Forum at the Woodrow Wilson International Center for Scholars in Washington.

Other analysts have been less optimistic, noting that China’s coal consumption went back up in 2017 and appears to be continuing in 2018.

“It looks like we have not yet reached that peak, but nevertheless I think it is within reach,” said Niklas Hohne, a partner at the Germany-based New Climate Institute. “It really depends now on their next developments.”

Guan’s conclusions are tentative, since changes in policy and the wider adoption of a Western-style consumer lifestyle by the Chinese could still turn that curve back upward. But he said structural changes in China’s economy are likely to mean the numbers posted in recent years are more than a short-term dip.

Beijing is burning less coal for power, demand for carbon-heavy products like steel and cement has dropped and the plants that remain have been modernized to run more efficiently. And as the country has become more prosperous, companies that once made their products in Chinese factories have moved those plants to lower-wage countries like Vietnam or Bangladesh.

“This is quite important, because it can play a demonstration role to the global South countries like India or Indonesia,” Guan said. The Chinese experience can show those large, still-developing nations that they too can bring prosperity to their people without an outsized carbon footprint.

“ All eyes are on China, and that’s why this issue is so important. ” — Niklas Hohne, New Climate Institute

“The future of climate change mitigation is in the hands of the global South countries,” he said.

China has cut back on coal not just to hit its Paris targets, but to reduce the notorious smog that wreaths its major industrial cities and the capital Beijing. It’s poured massive investments into wind and solar power, fueling a boom in renewable energy that’s made it cheaper worldwide. As its 1.4 billion people buy more cars, it’s trying to boost electric vehicles to reduce tailpipe emissions.

“Environmental authoritarianism has made some amazing leaps forward in terms of clean energy and crackdowns on pollution,” Turner said. “But at the same time, it still is vulnerable to the same pressures we feel here.”

The country’s power grid has been slow to incorporate the renewable capacity that’s been installed, leaving as much as 30 percent of those wind turbines and solar panels idled, she said. About two-thirds of its electric power is still generated by burning coal, roughly twice the share as in the United States. And while China is open to outside investment, its ruling Communist Party still keeps a firm hand on the economy—so when people start grumbling about losing jobs, the party will step in to boost the economy.

That may be happening now, fueled in part by the new trade war between Washington and Beijing, said Li Shuo, climate policy adviser for Greenpeace China.

“There is an increasing pressure from the policymakers in Beijing to keep GDP growth at a certain level, because GDP growth is an indicator of political stability,” Li said. If tit-for-tat tariffs depress one part of the economy, it can pump more money or cheap credit into others—and that often means carbon-intensive industries.

“If you produce one more ton of cement, you have some extra GDP regardless of whether that cement gets used or not,” Li said. “That’s basically what’s happening here.” As a result, coal consumption has been growing since late 2017 and is expected to continue growing this year at the fastest rate since 2011, he said.

“The transition has slowed since 2017, and we’re seeing more evidence of it slowing down,” he said.

Guan is still working on calculations for 2017, but he said he’s confident that even the past year’s increase won’t produce enough emissions to top 2013.

Even if China hasn’t hit its peak emissions already, it’s still expected to hit that goal and most likely hit it early, Li said. It’s also likely to hit its other Paris targets, like reducing the ratio of emissions to the size of its economy by 65 percent and boost its share of renewable power to about 20 percent.

But here’s where the fine print comes in: The longer it takes the hit a peak, the less ambitious it’s likely to be when negotiators sit down to hammer out new, steeper carbon cuts in 2020, Li said. Experts agree the current Paris pledges aren’t enough to keep the world from warming past two degrees, the point where scientists warn climate change could become catastrophic, and China’s pledge is ranked “highly insufficient” by the analysts at the Climate Action Tracker.

“They may be able to peak CO2 emissions much, much earlier and that would be a very good sign,” said Hohne, whose organization is part of the team behind the tracking website. But to do that China must not only keep cutting back on coal, but make sure that tailpipe emissions from its growing car and truck fleet don’t undo the carbon that once poured from smokestacks.

“All eyes are on China, and that’s why this issue is so important,” Hohne said.