Diplomatic tensions over global warming will take center stage at the G20 summit in Brazil this week, as negotiators at U.N. talks in Azerbaijan hit an impasse on climate finance that they hope leaders of the world's 20 major economies can break.

Negotiations were deadlocked Saturday at the midway point of the UN climate summit, with hopes pinned on G20 leaders intervening to strike a critical finance pact at the crunch talks.

The U.N.'s climate chief called on leaders of the world's biggest economies on Saturday to send a signal of support for global climate finance efforts when they meet in Rio de Janeiro next week, to help trigger a deal at COP29 talks.