By Kate Abnett, Olesya Astakhova and Virginia Furness BAKU (Reuters) -Countries at the COP29 summit tried to make progress on how to raise up to $1 trillion in climate finance for the world's most vulnerable,

At the United Nations climate talks in Baku, Azerbaijan, wars are top of mind for some leaders and activists who have converged to discuss ways to limit global warming.

A group of former leaders and climate experts said the annual U.N. COP climate talks were no longer fit for purpose and needed to be reformed, publishing a critical open letter mid-way through what has so far been a fractious summit.

The next major United Nations meeting on climate change, known as COP29, is about to get underway in Baku, Azerbaijan. These annual meetings are the key international summits as the world attempts to address the unfolding climate crisis.

The US election victory of Donald Trump - a known climate sceptic - could also prove to be a distraction, and some important leaders are not attending. COP29 is the world's most important meeting on climate change. It is led by the UN, and the 2024 event, the 29th such gathering, runs from 11-22 November.

Developing countries need at least $1 trillion per year by the end of the decade to cope with climate change, economists told U.N. talks in Baku, where early efforts to reach a finance deal risk being overshadowed by diplomatic rows.