The world expects the United States to uphold its commitments under the landmark Paris climate treaty, despite Donald Trump's vow to pull out of it, the incoming head of its UN implementing body told AFP Friday.

"The Paris Agreement is here," Moroccan foreign minister Salaheddine Mezouar, who took over stewardship of the 196-nation forum from France earlier this week, said in an interview.

"It's entry into force means that governments must face up to their responsibilities."

"It would be, I think, extremely difficult to retreat -- there's no turning back," he added.

The news that avowed climate change denier Trump had captured the US White House stunned participants arriving Wednesday at the 12-day talks, which run from November 7 to 18.

Delegates from several countries have taken a "wait-and-see" attitude after the victory by the New York real estate developer, who has vowed to pull the United States out of the hard-won deal, two decades in the making.

Under the Paris pact, countries have submitted voluntary pledges to cut the greenhouse gas emissions that cause dangerous global warming.

- 'Impatient to hear from US' -

The agreement commits nations to collectively capping Earth's average temperature increase at under two degrees Celsius (3.6 degrees Fahrenheit).

With barely 1.0C (1.8F) of warming to date, the world has already seen an uptick in deadly storms, droughts, heatwaves and flooding.

Mezouar has not yet reached out to Trump or his team, he told AFP.

"As the president of COP22" -- the acronym for the 22nd meeting of the Conference of the Parties -- "I am waiting with impatience to encounter the new American administration," he told AFP.

"I have absolutely no doubt as to our capacity to keep this momentum, and that the United States will pursue its commitments alongside the rest of the international community."

A report Thursday by three research groups, however, said the US was likely to miss its emissions reduction targets without new climate policies, which Trump has vowed he would not put in place.

Experts and diplomats here insist that the global market-based transition from a fossil fuels to clean energy is too far advanced to peel back.

But Trump's ascension has shaken hard-won political unity at the UN forum, which has also agreed to give hundreds of billions of dollars to poor, climate-vulnerable nations.

This uncertainty makes Mezouar's role even more crucial, said Liz Gallagher, an analyst at London-based thinktank E3G.

"The Moroccans need to be more proactive in driving the process, using all the diplomatic tools at their disposal, to make sure we get a clear outcome," she told AFP.

National carbon-cutting plans submitted under the Paris Agreement go into effect in 2020.

Some ministers arriving next week for a high-level session will announce more ambitious pledges, which still fall far short of what is needed to stave off devastating climate impacts.