The US is also under the spotlight at the conference, following the election victory of Donald Trump – a known climate sceptic.
On Monday, US President Joe Biden’s envoy John Podesta called out president-elect Trump’s view that climate change was a hoax and said the US team would continue to work on the deal passed at COP28 in 2023.
He added that Washington was also working on a deal passed last year in Dubai to triple renewable power by 2030.
Addressing the conference in Baku on Tuesday, UN Secretary General Guterres decried “doubling down on fossil fuels”.
“The sound you hear is the ticking clock,” he said.
“We are in the final countdown to limit global temperature rise to 1.5 degrees Celsius and time is not on our side.”
He called 2024 a “masterclass in climate destruction” with disasters being “supercharged by human-made climate change”.
The UN’s World Meteorological Organization previously said that 2024 is on track to be the world’s warmest year on record.
Guterres said “a new finance goal” was needed, with wealthiest countries paying the most.
“They are the largest emitters, with the greatest capacities and responsibilities,” he said. “Developing countries must not leave Baku empty-handed.”
The Azerbaijani president’s comments are unlikely to derail talks behind the scenes, which are largely about getting more cash for poorer countries to help implement their climate plans.
Developing nations are calling for richer countries to agree together on a fund that could add up to $1 trillion, using public and private money.
Leaders of most of the world’s biggest polluters were not present in Baku, including Biden, France’s leader Emmanuel Macron and India’s Narendra Modi.