Climate changers are sweating Donald Trump’s victory, worried that a president-elect who who has referred to their global environmental concerns as a “hoax” will affect their recent progress.

Trump had said he would “cancel” the United States’ participation in the Paris Agreement – the “world’s first global climate pact” – if he were to win the White House, reported the Los Angeles Times.

Less than a year ago, the U.S. along with nearly 200 other countries adopted the Paris Agreement, USA Today noted. Trump has said he will renegotiate the deal.

Climate change advocates attending the Marrakech Climate Change Conference assured attendees the agreement would continue on.

“We’ve got a new administration and a new opportunity to surge forward on climate action,” said Mariana Panuncio-Feldman, a senior director for World Wildlife Fund, adding that it was President Barack Obama who played a major role in finalizing the Paris deal.

“Our new president needs to carry that legacy forward and make good on the promise to make America into the world’s clean-energy superpower,” she said.

Others were more realistic about the challenge of keeping Obama's promises with Trump in the oval office.

“Donald Trump has the unflattering distinction of being the only head of state in the entire world to reject the scientific consensus that humans are driving climate change,” said Michael Brune, the Sierra Club’s executive director.

“Because they were done with existing authority, not through Congress, it’s easier for another administration that has another view to roll all those things back and I worry a lot that that’s what’s about to happen,” said Jason Bordoff, the director of Columbia University’s Center on Global Energy Policy and a former energy advisor to Obama.

Carola Ortega, 21, a resident in New Jersey and student observer in Marrakech, also spoke of the challenges ahead.

“Before, we were told our job would be to use the next months to try to push the Hillary Clinton administration to do more when it came to climate change,” she said. “After the election, we were told we would have to try to push the Trump administration to do something, anything.”