Nations remain in deadlock over a crucial pact on climate aid, with divisions over who pays, and how much, threatening chances of a deal being landed at next month's COP29 summit.
The UN conference starts just six days after the US election and the possible return of Donald Trump -- who pulled the United States out of the Paris climate agreement -- looms over the negotiations.
World leaders will attend a two-day gathering at the opening of the summit in Azerbaijan, which faces scrutiny as the latest petrostate with limited tolerance for dissent to host the preeminent annual climate talks.
Organisers say over 50,000 attendees are expected between November 11-22 in the capital Baku.
COP29 has been dubbed a "finance COP" because rich countries most responsible for global warming are supposed to commit to substantially increasing their assistance to poorer countries for climate action.
The current amount of $100 billion a year expires in 2025 and is considered well below what developing nations need.
But major donors, including the European Union and United States, have still not said how much they are willing to pay, resisting pressure to put even a ballpark figure on the table.
They are being urged to turn billions into trillions at COP29, but the appeal for vast new sums of government money comes at a time of political and economic uncertainty for many donors.
- 'Complex negotiations' -
Azerbaijan, a former Soviet republic between Russia and Iran with little experience in international diplomacy, has urged parties to make the most of the "critical final stage" before COP29.
On Wednesday, government ministers will gather in Baku to try and make headway.
"These are complex negotiations –- if they were easy, they would have been resolved already –- and ministers will succeed or fail together," said COP29 president Mukhtar Babayev, a former oil executive and Azerbaijan's ecology minister, in September.
"The eyes of the world are now upon them."
Observers say climate leadership has been missing in action this year, with attention elsewhere even as fires, floods, heatwaves and drought have hit every corner of the globe.
As they stand, international efforts to reduce planet-heating greenhouse gases are insufficient to cap global warming to 1.5 degrees Celsius above pre-industrial levels, the safer limit of the Paris agreement.
"We are potentially headed towards 3C of global warming by 2100 if we carry on with the policies we have at the moment," Jim Skea, chairman of the Intergovernmental Panel on Climate Change, told The Telegraph in October.
Developing nations suffer disproportionately from climate change and are seeking a deal at COP29 that ensures upwards of $1 trillion annually in "climate finance" -- 10 times current amounts.
They want the new agreement to cover not just money for low-carbon technology and adaptation measures like sea walls but for disaster recovery as well, something developed countries do not want to include.
- Greenwashing -
Countries obligated to pay -- a list of industrialised nations drawn up in 1992, and reaffirmed in the 2015 Paris agreement -- intend to keep doing so, but want wealthy emerging economies to help out.
This has been flatly rejected by developing nations, who say adding donors is not up for discussion.
"We should not let others turn away from their responsibility," said Evans Njewa of Malawi, who chairs the Least Developed Countries group of the 45 most climate vulnerable nations.
The spectre of Trump's return was one of the "main issues" clamming up the negotiations, said Michai Robertson, lead climate finance negotiator for the Alliance of Small Island States.
"You see a lot more hesitancy in general from those who typically contribute. I do think... they're waiting to see whether there will be a government that will hopefully stay within the Paris agreement," he said.
With the negotiations stalled, Azerbaijan has asked fossil fuel producers to raise $1 billion for climate action and has promised, as an economy wedded to oil and gas, to make the first donation.
Campaigners slammed this as greenwashing by a country expanding its own fossil fuel production, and whose strongman leader called Azerbaijan's gas "a gift of the gods".
Andreas Sieber, from activist group 350.org, said Azerbaijan's reluctance to address the phase-out of fossil fuels -- a pledge made at COP28 in oil-rich United Arab Emirates -- had "become a worrisome pattern".
- Grim reality -
COP29 is the biggest international event Azerbaijan has ever hosted, bringing unprecedented scrutiny to a tightly-controlled state that Human Rights Watch has described as "repressive".
Amnesty International and US senators have raised concerns about a crackdown in Azerbaijan in recent months, with critical voices jailed on dubious charges.
"The situation on the ground is quite grim... By the time Azerbaijan actually hosts COP29 there won't be much of civil society left," said independent Azerbaijani journalist Arzu Geybulla.
The summit has a much lower profile than the extravaganza in Dubai and it remains unclear how many world leaders will attend, with COP30 in Brazil next year considered of greater import.