An obscure negotiating session of the UN climate talks is suddenly in the spotlight – but for all the wrong reasons.

The United Nations opens its interim talks here in Bonn on Monday, a two-week negotiating session that traditionally sets the agenda for the larger fall meetings.

But as with so many political issues this year, the climate is anything but quiet: President Trump is mulling an exit from commitments Barack Obama inked in Paris in 2015, Europe stands poised to abandon its leadership role in emissions reduction, and delegates are watching to see if China, India or another country steps to the front and assumes the mantle of climate leadership.

“There are lots of questions about the intentions around the commitments made by northern countries,” said Clare Shakya, director of the Climate Change Group for the International Institute for Environment and Development, a London-based group negotiating on behalf of a coalition of the 48 nations deemed by the UN as the least developed countries in the world.

“The geopolitics has all gone wrong since Paris.”

In Paris two years ago, almost 200 nations inked a landmark, albeit nonbinding, agreement to cut emissions to stem climate impacts. Left for future negotiations were the details—rules, accountability, transparency and governance. Drafting this so-called “Paris rulebook” is agenda item No. 1 in Bonn.

“This is basically the user’s manual of the Paris agreement,” said Paula Caballero, global director of the Climate Program for the World Resources Institute. “It’s important to help clarify the pace and the trajectory of climate action by all parties.”

“This is what’s going to give both companies and countries confidence to ramp up their climate ambition.”

Storm clouds loom

Trump advisors meet on Tuesday to discuss whether the U.S. should withdraw from the pact. The United Kingdom, distracted by Brexit, appears inclined to use its climate finance moneys for trade deals, Shakya said. UK’s absence imperils European leadership, she added, as France and Germany alone might not have the pull to bring more reluctant countries, such as Poland, along.

“We might see the disappearance of the EU,” Shakya warned. “The U.S. was only there for a moment, but it was there.”

China has traditionally focused inward on the global stage. “The question is, ‘Can they step up and become a global leader?’” Shakya asked. “They’re seeking to.”

The United States will still have a negotiating team at the talks, although it will be small, with little real power. The U.S. still co-chairs the committee working to improve transparency in efforts to track progress on emissions cuts, said Andrew Light, a former senior advisor to the U.S. Special Envoy on Climate Change who is now a fellow at the World Resources Institute. And many of the negotiators are unchanged from the team that helped put together the Paris deal.

On the question of whether a U.S. withdrawal creates a difficult backdrop, Cabellero said, “the answer is definitely ‘yes.’”

“But this is not the first time these talks have faced difficulty.”

Several signposts suggest global efforts to curb emissions can succeed despite the absence of the globe’s economic heavyweights:

Almost 30 countries have submitted emissions reductions plans for review in Bonn. China’s president, Xi Jingping, speaking at the World Economic Forum in Davos in January, called Paris a “hard-won achievement” that all parties should stick to “rather than walk away.”

The private sector, where much work on climate solutions is underway, needs a rulebook to ensure the playing field remains fair and level. “There will be collateral damage to the United States’ businesses if the U.S. becomes a pariah on climate negotiations,” Light said.

India intends to triple its renewable energy capacity and is walking away from coal, hoping to use the Bonn talks to show off both that data and their commitment to increased transparency and ambition, said Yamide Dagnet, a senior associate at WRI’s Climate Action Initiative.

Mexico, Brazil and some of the Least Developed Countries could become climate leaders. “There are huge opportunities for the emerging economies to step into the vacuum,” Shakya said. “We’re very excited by the power that is coming to this grouping.”

That shift in global politics could be the main story out of the climate talks in Bonn the next two weeks.

“International leadership on climate is more diffuse than ever before,” Caballero said.

“Obviously it would be ideal and we would prefer if the U.S. stays in the agreement and works to develop rules that will underpin Paris.

“But the negotiations on the Paris Agreement will proceed. The willingness is there.”