John D. Sutter is a columnist for CNN who focuses on climate change and social justice. Follow him on Snapchat , Twitter and Facebook or subscribe to his email newsletter.

Bonn, Germany (CNN) There's a building here in Germany where Donald Trump doesn't exist -- or where people are trying very hard to believe that.

I stopped by on Tuesday to see what on Earth that's like.

The venue is the World Conference Center Bonn, and it's nothing to write home about on its own: glass ceilings, fluorescent lights and meeting rooms named for cities like Addis Ababa, Tokyo and Santiago. It's not far from the banks of the Rhine.

Inside, however, negotiators from more than 140 countries are gathering to talk about one of President Trump's least favorite topics: climate change.

Specifically the Paris Agreement, which seeks to shove the world out of the fossil fuel era, reduce pollution and avoid the very worst of global warming.

Given Trump's bombastic rhetoric on this subject -- as a presidential candidate he threatened to "cancel" the Paris agreement, and the US's role remains unclear as members of his administration continue to debate the pros and cons of withdrawal -- you'd think the climate wonks here would be talking all Trump all the time.

But the opposite is mostly the case.

"When someone important leaves the table -- (any) table -- there's one of two things you can do," said Ronald Jumeau, climate change ambassador from Seychelles, a small island nation that could drown beneath rising seas as warming continues. "Either you watch them going out of the door and start beating your chest and puling out your hairs saying, 'What are we going to do?!'" Or, he said, you go to work anyway.

"We're not all going to rush out and leave the table unattended."

'Let's dream big!'

Call it the other climate denial, but I found the enthusiasm echoing around the halls of Bonn refreshing. The world is bigger than the United States, and it's bigger than Donald Trump. Climate negotiators and observers here care little for the will-he, won't-he speculation game. US participation matters to them, certainly. But they're working to try to ensure the agreement could continue either way.

They're hosting panels on climate education and going to meetings with inscrutable titles like, "SBSTA Informal consultations on technology framework under Article 10, paragraph 4, of the Paris Agreement." They're trying to draft a rough outline of the so-called "rulebook" for the Paris Agreement ready to set the stage for negotiations later this year.

In summary: They're planning for a future with or without Trump.

"The science (of climate change) is grim, I don't deny that," said Sarah Marchildon, head of the Momentum for Change initiative at the United Nations Framework Convention on Climate Change. "But at the same time I'm going to choose hope. I'm going to choose optimism."

"Let's dream big! Let's act bigger!" a rosy-cheeked panel moderator said after a discussion that did not mention the US administration. Signs all over the convention center remind attendees that, "We're accelerating climate action."

Nick Nuttall, spokesman for the UN Framework Convention on Climate Change,or UNFCCC, told me Trump hasn't been coming up by name. "I don't know what (the delegates) are discussing over a beer or a pretzel, but in the hallways here, no," he said.

The talks continue through Thursday.

'High noon'

There are representatives from the Trump administration present at the talks in Bonn, although they have been keeping a low profile and declined my interview request. Trigg Talley, from the US State Department, is among the negotiators. On Saturday, he had the unenviable task of answering questions from other countries about US climate and energy policy.

"High noon, time for the US," the moderator said in introducing him.

Li Shuo, a Greenpeace employee in the room, told me the audience "giggled."

Talley didn't offer many specifics.

"So, as you know ... we have new US administration," he said in the meeting. "And along with that comes a substantial change in priorities and approaches ... Our climate policies are under review."

According to Nuttall, the UNFCCC spokesman, the United States sent 16 negotiators to Bonn this month. Compare that to 38 people from China and 26 from Fiji, which is the host of the upcoming COP23 talks.

'If the US steps back...'

There are, of course, delegates who will admit they are frightened about what would happen if the US abandons the Paris Agreement. Chai Qimin, a director at China's National Center for Climate Change Strategy and International Cooperation, told me it would be harder for China to boost its green ambitions if the US leaves.

"China promised to stick to our commitments and fulfill our responsibility on addressing climate change. We have confidence on our policies already made," he said, noting that he was speaking as a private individual and professor, not for the Chinese government.

"If US steps back, the Chinese government still will fulfill its (climate pledges to the Paris Agreement). But there would be different voices within the country, especially form the fossil fuel industries." Those industry voices might raise new objections to China's participation in the Paris Agreement if the US bails, he said.

"The US role cannot be filled by China," he said, "just like China's role cannot be replaced by the United States."

'Not a catastrophe'

Much of the optimism in Bonn is built off of good news from China and India.

China's consumption of coal has been declining for three consecutive years. India is investing heavily in renewable energy, with the government reportedly considering a plan to make all new cars electric by the early 2030s.

On Monday, Climate Action Tracker released a report saying that China and India are doing so much better than expected at slowing their rates of pollution that they will make up for additional US pollution that's expected as a result of Trump's climate policy changes. So it remains possible for the world to meet the terms of the Paris Agreement even if the US steps away temporarily, said Bill Hare, CEO and senior scientist of Climate Analytics, a non-profit that worked on the report.

"In the long run the US has to be in the game and has to reduce emissions, otherwise we won't get to the Paris goals," Hare told me. "But in the short run it's not a catastrophe. It's not insignificant, but it's not a catastrophe."

Not a catastrophe.

Perhaps that's the best we can hope for.

Or perhaps there's still time for Trump to change his tune.