World leaders pose for a group photo at the official opening of the COP29 Summit in Baku on Tuesday.

Several influential world leaders have opted not to attend an action summit this week at the center of climate talks in Azerbaijan. High on the agenda is a deal to boost climate funding for developing countries.

The two-day World Leaders Action Summit at COP29 got under way on Tuesday in Baku, Azerbaijan, with around 100 leaders taking part, although there are some noticeable absentees.

The top priority at this year's summit is expected to be landing a deal to boost funding for climate action in developing countries. Some are pushing for the current pledge of $100 billion (€93 billion) a year to be raised by ten times that amount at COP29 to cover the future cost of shifting to clean energy and adapting to climate shocks.

• Without adequate finance, developing nations have warned that they will struggle to offer ambitious updates to their climate goals, which countries are required to submit by early next year.

The leaders of the 13 biggest emitters of carbon — countries responsible for more than 70% of 2023's heat-trapping gases — will not appear at this year's gathering.

Chinese President Xi Jinping, US President Joe Biden, and also India's Narendra Modi and France's Emmanuel Macron are among G20 leaders skipping the event.

• "It's symptomatic of the lack of political will to act. There's no sense of urgency," climate scientist Bill Hare told the Associated Press.

Nevertheless, Azerbaijan's President and COP2 host Ilham Aliyev, UK Prime Minister Keir Starmer and Turkey's President Recep Tayyip Erdogan are among the nearly 50 leaders set to speak on Tuesday.

COP29 lead negotiator, Azerbaijan's deputy Foreign Minister, Yalchin Rafiyev, emphasized at a press conference on Tuesday that "success doesn't depend on one country alone."

"Unless all countries can slash emissions deeply, every country and household will be hammered harder than they currently are. We will be living in a nightmare," he said.

UN Secretary General Antonio Guterres warned that time was running out in the fight against climate change. "We are in the final countdown to limit the global temperature rise to 1.5 degrees Celsius," Guterres said. "And time is not on our side," he added.

• The Paris Agreement, a legally binding climate treaty signed by 196 countries after COP21 in 2015, calls for limiting global warming to 1.5 degrees compared to pre-industrial levels. However, this goal looks increasingly unlikely to be met. This year the limit is expected to be exceeded for the first time, while the target is a multi-year average.

• Guterres described 2024 as "a masterclass in climate destruction." The UN chief also said that nations needed to reach an agreement that does not leave poorer countries "empty-handed" in their fight against climate change. "Developing countries must not leave Baku empty-handed. A deal is a must," Guterres said.

In an address on Tuesday, Azerbaijan President Aliyev repeated a controversial quote that oil, gas and other natural resources are a "gift of the God" and said nations should not be judged by their natural resources and how they use them.

"Quote me that I said that this is a gift of the God, and I want to repeat it today here at this audience," he told delegates.

Azerbaijan has seven billion barrels of oil reserves and was one of the first places in the world to start commercial oil production.