When Donald Trump was a candidate for president, he criticized scientists who blamed pollution for rising temperatures on Earth's surface.

Trump rejected scientific documentation of climate change, calling it a hoax or unreal. And he promised to pull out of the Paris Agreement on climate change. That agreement was the product of negotiations involving about 200 countries.

Trump won the presidential election in the United States. He will replace Barack Obama as president on January 20, 2017.

Government officials and scientists are in Morocco this month for climate talks. They worry that if Trump pulls out of the Paris agreement, as he promised, it will have a major effect on their work.

"This is critical to protect our planet, safeguard the most vulnerable, and drive shared prosperity," said United Nations Secretary-General Ban Ki-moon. He spoke at the opening of the conference in Marrakech.

Ban said he hopes Donald Trump will listen to scientists and "understand the seriousness" of climate change.

Trump has said he plans to pull back from Obama's climate change rules during his first 100 days in office. He said he wants to put American coal miners back to work and make the United States more energy independent.

Mike Duncan heads The American Coalition for Clean Coal Electricity. The group opposes Obama administration climate change regulations.

Duncan told VOA that Trump can move the country away from "costly" rules that "limited our access to affordable and reliable power."

Al Gore served as U.S. vice president during the administration of former President Bill Clinton. Gore has been warning for years that temperatures will continue rising if greenhouse gases like carbon dioxide are not reduced. And that means more deadly storms and natural disasters, and land falling into the sea, he said.

Gore released a statement after Trump won the presidential election.

"President-elect Trump said he wanted to be a president for all Americans," Gore said. "In that spirit, I hope that he will work with the overwhelming majority of us who believe that the climate crisis is the greatest threat we face as a nation."

Trump's election was likely to be a subject of discussion at the climate conference taking place in Marrakesh, Morocco. The meeting was called to discuss the next steps to move the Paris Agreement forward.

Secretary of State John Kerry was asked by a reporter how he felt, given that Trump has said he will cancel some U.S. climate change regulations.

Kerry told reporters that Trump's election makes the meeting in Morocco, in his words, "perhaps even more important."

I'm Bruce Alpert.

Henry Ridgwell reported on this story for VOANews. Bruce Alpert adapted this story and did additional reporting for Learning English. George Grow was the editor.