Getting a deal on the money has proved slow-going at the talks in Azerbaijan's capital of Baku, and the latest draft of the negotiating text arrived several hours later than scheduled as delegates entered, in theory, the closing 48 hours.
The talks, which began on Nov. 11, are due to end on Friday at 1400 GMT, but COP summits have a history of running long.
Major polluters must help nations most vulnerable to climate change.
A previous goal of $100 billion per year, which expires in 2025, was met two years late in 2022, the OECD said earlier this year, although much of it was in the form of loans rather than grants, something recipient countries say needs to change.
Planet-warming carbon dioxide emissions from oil, gas and coal rose to a new record high this year, according to preliminary research from an international network of scientists at the Global Carbon Project.
A group of lenders, including the World Bank, announced a joint goal on Tuesday of increasing this finance to $120 billion by 2030, a roughly 60% increase on the amount in 2023.
Environmental impacts, largely stemming from air travel, directly contradicts COP29's core mission.
Landing a new accord to boost money for climate action in developing countries is the top priority of negotiators at the UN COP29 summit in Azerbaijan.
The Global Carbon Budget report, published during the U.N.'s COP29 climate summit in Azerbaijan, said global CO2 emissions are set to total 41.6 billion metric tons in 2024, up from 40.6 billion tons last year.
"Many of you have been reporting on the climate implications of political events in the last weeks. I'll just say this: our process is strong. It's robust, and it will endure," Simon Stiell told reporters at the COP29 talks in Baku.
Here is some of the latest climate research
In a fresh report, UNHCR pointed to how climate shocks in places like Sudan, Somalia and Myanmar were interacting with conflict to push those already in danger into even more dire situations.
US envoy John Podesta acknowledged the next US administration would "try and take a U-turn" on climate action, but said that US cities, states and individual citizens would pick up the slack.
The period from 2015-2024 will also be the warmest decade ever recorded, the UN's World Meteorological Organization (WMO) said in a new report based on six international datasets.
Here's what the summit leaders had to say at the opening ceremony
The master's message was a testament: "If we want to prevent the disappearance of the truffle, we must protect the forests, stop polluting the waterways and plant new 'truffle' trees".
A guide to some of the terms in play at this year's COP29 discussions
Delegates gathering in Azerbaijan's capital of Baku are hoping to resolve the summit's top agenda item – a deal for up to $1 trillion in annual climate finance for developing countries.
Countries come to Baku for the main United Nations forum for climate diplomacy after new warnings that 2024 is on track to break temperature records, adding urgency to a fractious debate over climate funding.