UN Secretary-General Antonio Guterres on Sunday called on G20 leaders gathering in Rio de Janeiro to rescue stalled concurrent UN climate talks in Azerbaijan by showing "leadership" on cutting emissions.
"A successful outcome at COP29 is still within reach, but it will require leadership and compromise, namely from the G20 countries," Guterres, who will attend the summit of the world's biggest economies starting Monday, told a press conference in Rio.
The annual UN talks in Baku are deadlocked at the midway point, with nations no closer to agreeing a $1 trillion deal for climate investments in developing nations after a week of negotiations.
The talks are stuck over the final figure, the type of financing, and who should pay, with Western countries wanting China and wealthy Gulf states to join the list of donors.
All eyes have turned to Rio in the hope of a breakthrough.
"The spotlight is naturally on the G20. They account for 80 percent of global emissions," Guterres said, calling on the group to "lead by example."
Climate was an issue advanced by several of the leaders as they converged on Rio.
US President Joe Biden, making a stopover in the Amazon, talked up $11 billion in bilateral climate financing his administration has allocated this year.
He also -- in a reference to President-elect Donald Trump taking over from him in two months -- declared that "nobody" could reverse the "clean energy revolution" directed by his government.
European Union chief Ursula von der Leyen and South African President Cyril Ramaphosa in Rio jointly launched a campaign to boost renewable energies in Africa.
"Tripling renewables globally until 2030 would mean a cut of 10 billion tonnes of CO2 emissions," von der Leyen said at an event put on by the advocacy group Global Citizen.
She said the EU was increasing investment around the world for the building of infrastructure of renewables, "specifically in Africa" through the bloc's Global Gateway program -- designed to rival China's Belt and Road Initiative.
The European Union is the world's biggest contributor for climate financing, most of which goes through multilateral funds.
Chinese President Xi Jinping -- whose country is the planet's biggest polluter -- made his own plea for the G20 to step up international cooperation against climate change.
The leaders of the world's biggest economies should coordinate efforts in areas such as "green and low-carbon development, environmental protection, energy transition and climate change response," he said in a tribune published in Brazil's Folha de Sao Paulo newspaper.
The G20 should "provide more funding, technology and capacity-building support to Global South countries," he said.
Brazil is hoping to channel the focus on climate in the two-day G20 summit for it to feature prominently in the meeting's final declaration.
Marina Silva, Brazil's environment minister, said it was "fundamental" that the G20 participants "do their homework" and see to it that the COP29 negotiations move forward.
