Nations that adopted the Paris Agreement with champagne two years ago, regroup next week amid grim omens of climate peril and with an anxious eye on Donald Trump's America.
The November 6-17 meeting in Bonn, Germany, is the first for UN climate envoys since the US president announced he will extricate Washington from the deal, carefully crafted over many years and helped over the finish line by Trump's predecessor Barack Obama.
In a year marked by severe flooding in Asia, drought in Africa and an exceptional North American hurricane season, Washington's position "remains unchanged", a state department official said.
"The United States intends to withdraw from the Paris Agreement as soon as it is eligible to do so".
This can officially happen no sooner than November 4, 2020.
In the meantime, the world's biggest historical greenhouse gas polluter will send a delegation "to represent US interests" at the 23rd round of annual UN talks, with Fiji as president, in the former German capital.
According to Fiji's top negotiator Nazhat Shameem Khan, veteran US envoys have expressed the intention to continue to "take part constructively".
"We should not entertain the US as a destructive force in Bonn," warned Mohamed Adow of Christian Aid, which lobbies for poor country interests at the two-decades old UN process.
"Since they have already announced their decision to withdraw, they shouldn't be actively influencing an agreement they don't intend to be party to," he told AFP.
- 'Miserable future' -
A total of 195 nations agreed in the French capital in 2015 to limit average global warming caused by greenhouse gases from fossil-fuel burning to under two degrees Celsius (3.6 degrees Fahrenheit) over pre-industrial levels, and to 1.5 C if possible.
The 1 C mark has already been passed.
Countries, including the United States, made non-binding pledges of emissions cuts in support of the goal, though scientists say the shortfall is still far too great.
The talks open days after the UN's environment organ, UNEP, warned that current pledges sentence the world to a 3 C-warmer future, fuelling heatwaves, superstorms, drought, and sea level rise.
Warned UNEP head Eric Solheim: "we are not doing nearly enough to save hundreds of millions of people from a miserable future."
Costa Rica's environment minister Edgar Gutierrez-Espeleta, president of the UN Environment Assembly, said the Paris Agreement may have boosted climate action, but "momentum is clearly faltering."
"We face a stark choice: up our ambition or suffer the consequences," he said this week.
Some 20,000 people are due to attend the 23rd UN "Conference of Parties" or COP23, with UN chief Antonio Guterres, French President Emmanuel Macron, German Chancellor Angela Merkel, California governor Jerry Brown, former New York mayor Michael Bloomberg, and actor-turned governor Arnold Schwarzenegger expected among them.
This year's conference is the first with a small island developing state as president.
The gathering is expected to be quite technical in nature. It is meant to design common rules for countries to weigh the adequacy of their individual and common greenhouse gas pledges, and to ramp these up to get closer to the 2 C target.
- 'Urgency' -
"Given the American decision," the conference will also "be an important political moment for countries to reaffirm their commitment to the Paris Agreement," said former French negotiator Laurence Toubiana who now heads the Europe Climate Foundation, an NGO.
"It will be important to listen to the statements of governments... to see that countries are still committed, that there is no rowing back," she told AFP.
Since the pact was adopted two years ago, the Palestinian Authority and more recently Nicaragua, have joined the pack.
Now, "the only country that is with the US (outside of the agreement) is Syria," said Adow. "That tells you the direction of travel."
Many hope the Fijian presidency will breathe new life into a process that has struggled to focus ever since the election last November of Trump, who has described climate change as a "hoax".
"We (Fiji) bring to the negotiations the sense of urgency that comes from living in the Pacific and seeing at first hand the impact of climate change on our people," said Khan.
"So it is that urgency that we infuse in the discussions in Bonn."
Bonn police have so far been notified of about a dozen marches planned for the duration of the conference, starting with an estimated 10,000 green activists taking to city's streets on Saturday.