MARRAKESH, Morocco (Reuters) - U.S. Secretary of State John Kerry had hoped his presence at a Marrakesh conference to decide on the finer points of a historic agreement to stave off climate change would be a victory lap.

Instead, he found himself having to address the uncertainty created by the election of Donald Trump, and what his presidency might mean for the U.S. commitment to the 2015 Paris agreement to cut global greenhouse gas emissions.

In a speech on Wednesday, Kerry urged countries to treat the earth’s changing climate as an urgent threat, citing melting glaciers, stronger storms, and record-breaking droughts.

“While I can’t stand here and speculate about what policies our president-elect will pursue, I will tell you this: In the time that I have spent in public life, one of the things I’ve learned is that some issues look a little bit different when you’re actually in office compared to when you’re on the campaign trail,” he said.

Trump has called climate change a hoax, and said he would rip up the Paris deal, halt any U.S. taxpayer funds for U.N. global warming programs, and revive the U.S. coal sector.

If he follows through on his promises, he would undo the legacy of President Barack Obama, who has made climate change a policy priority and called the rising temperatures and other fallout from climate change “terrifying”.

Kerry spoke of his trip last week to Antarctica, where he met scientists alarmed at the trends.

“CRITICAL JUNCTURE”

“For those in power in all parts of the world, including my own, who may be confronted with decisions about which road to take at this critical juncture, I ask you, on behalf of billions of people around the world: Don’t take my word for it ... I ask you to see for yourselves.”

The Paris accord won backing from enough countries to enter into force on Nov. 4, four days before the U.S. election, and the conference in Morocco was in part a celebration of that landmark.

The United States worked closely with China last year to build support for the Paris agreement, and the partnership of the two biggest greenhouse gas emitters helped persuade other countries to back the agreement.

The agreement seeks to phase out net greenhouse gas emissions by the second half of the century and limit global warming to “well below” 2 degrees Celsius (3.6 Fahrenheit) above pre-industrial times.

For now, the United States is proceeding as usual. The White House presented a plan in Marrakesh, in the works long before Trump’s victory, for a “deep decarbonisation” of the U.S. economy by 2050 that foresees an 80 percent cut in emissions from 2005 levels.

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Without mentioning Trump, the 111-page plan said it was “achievable, consistent with the long-term goals of the Paris Agreement, and an acceleration of existing market trends” that would “require increasingly ambitious decarbonisation policies”.

But Trump’s election raises the prospect of the United States not fulfilling its commitments and has raised doubts among delegates in Marrakesh about whether Washington will still be a partner in the agreement come mid-century.

U.S. “ESSENTIAL”, SAYS CHINA

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China, the biggest greenhouse gas emitter, ahead of the United States, said it would push ahead with its promises to limit climate change and urged Trump to reconsider.

“As the largest developed economy in the world, U.S. support is essential. We have to expect they will take a smart and wise decision,” Liu Zhenmin of the Chinese delegation told a news conference in Marrakesh.

In his speech, Kerry emphasized the dangers of inaction.

“2016 is going to be the warmest year of all. Every month so far has broken a record,” he said.

“At some point, even the strongest skeptic has to acknowledge that something disturbing is happening.”

It is unclear what Trump will do on climate policy. On other issues, he has made contradictory statements and has said unpredictability is an asset in international negotiations.

Trump denied during a debate with his election rival Hillary Clinton that he had called climate change a hoax perpetrated by the Chinese, but in speeches and on Twitter he has repeatedly called it a hoax.