Wealthy nations are yet to offer the hundreds of billions of dollars that economists say are needed to help the developing world cut emissions

Leaders of the world’s biggest economies meeting in Rio de Janeiro on Monday must agree to provide the finance that the world’s poorest need to tackle the climate crisis or face “economic carnage”, the UN has warned.

The G20 nations are about to gather in Brazil for two days of talks, while many of their ministers remain in Azerbaijan where crucial negotiations at the Cop29 climate crisis summit have stalled. Rich countries’ governments have not yet put forward the offers of hundreds of billions of dollars in financial aid that economists say are needed to help poorer countries cut their greenhouse gas emissions and adapt to the impacts of extreme weather.