Many fear that withdrawal by the United States, a champion of the deal under Barack Obama, would shatter the political goodwill.
A week after climate change denier Donald Trump's election to the White House, world leaders will on Tuesday address a key UN meeting in Marrakesh to keep a climate rescue plan on track.
UN chief Ban Ki-moon, King Mohammed of conference host Morocco, and France's President Francois Hollande will open a "high-level" segment of the annual UN forum -- the first since last year's adoption of the Paris Agreement to stave off calamitous global warming.
This will be followed by speeches from nearly 60 heads of state and government from mainly African countries, but also some from Europe and several island states.
"We expect of the heads of state to reiterate their commitment (to the deal)... and send a strong message to Trump and the rest of the world," Celia Gautier of the Climate Action Network, a grouping of NGOs, told AFP on Monday.
The election of Trump, who has called climate change a "hoax" and has threatened to "cancel" the Paris pact, has been uppermost on the minds of many delegates and negotiators gathered since last Monday to thrash out a roadmap for putting the agreement into action.
The hard-fought deal set an objective of limiting average global warming to two degrees Celsius (3.6 degrees Fahrenheit) over pre-Industrial Revolution levels by cutting planet-heating greenhouse gases from burning coal, oil, and gas.
Many fear that withdrawal by the United States, a champion of the deal under Barack Obama, would shatter the political goodwill built up over years of negotiations, and put the very planet-saving goals of the deal at risk.
While waiting for news from Washington, many now look to the rest of the world to strongly restate their commitment to the pact -- with or without the US.
All eyes will be on Marrakesh, where 39 kings and presidents and 18 prime ministers are scheduled to address the 22nd Conference of Parties (COP22 for short) of the UN's climate convention, which gathers 196 nations and the EU bloc.
To date, 109 of the 197 parties have officially ratified the Paris Agreement, which entered into force on November 4 after crossing the threshold of 55 ratifications by countries representing 55 percent of greenhouse gas emissions.
They included the United States, which represents about 14 percent of global emissions, and China which accounts for 25 percent.
Beijing's climate envoy Xie Zhenhua stressed Monday that tackling climate was a "common and shared responsibility".
"International cooperation is a must for us to address climate change," he said in Marrakesh.
In Marrakesh, developing nations have been pushing for stronger finance commitments from the developed world, particularly for infrastructure to help them better cope with climate change-induced harms.
Scientists say warming over 2 C will yield dangerous sea level rise, harsher storms and droughts, disease spread and conflict over ever-scarcer resources.
"Now, more than ever, governments meeting in Marrakesh must commit to action to protect millions of vulnerable people from climate change," said Oxfam, which fights for poor people's interests at the climate talks.
Among the speakers on Tuesday's agenda is Sudan's Omar al-Bashir, for whom the International Criminal Court has issued an arrest warrant for war crimes, crimes against humanity and genocide in Darfur.
Approached for comment, the UNFCCC said by email on Monday Bashir was invited by Morocco, which is not a party to the court's founding Rome Statute.
"If even al-Bashir can contribute to the global climate effort, then President-elect Donald Trump will have no excuse," commented climate activist Mohamed Adow of ChristianAid.