The world's climate goal is hanging by a thread and countries need to dig deeper to provide the finance and set the policies needed to shift to a low-carbon economy, delegates to climate events in London heard this week.

As the first weeks of the Northern Hemisphere summer bring deadly heatwaves, the 45,000-plus attendees at London Climate Action Week events were warned that concrete commitments were needed at climate talks in Azerbaijan in November.

In the capital Baku, countries will seek agreement on a new annual target for the amount of investment needed in developing countries to replace the yearly $100 billion that rich countries had pledged in climate finance from 2020 and met in 2022.

Countries also need to make more ambitious plans to cut emissions to 2035, as average global temperatures hit fresh monthly records, some of which breached the world's target temperature increase limit of 1.5 degrees Celsius above the pre-industrial average. "We need finance at scale," Selwin Hart, Special Adviser to the United Nations Secretary-General on Climate Action said at an event this week.

"Despite the very clear economic case for urgency and ambition, we're simply not moving fast enough. And in my view, the climate crisis is a crisis of political will," he said.

A 2023 study estimated that by 2030 developing countries would need to invest around $2.4 trillion a year to decarbonise their economies, of which $1 trillion will come from external sources.

Preliminary talks earlier this month in Bonn, Germany, exposed continuing rifts among the world's biggest economies over who should contribute – and by how much.

"It's too early to talk about the quantum," Canada's Ambassador for Climate Change Catherine Stewart said in an interview, with more discussion needed on where the money will come from and "the fact we need everybody coming to the table".

Mahmoud Mohieldin, U.N. Climate Change High-Level Champion for Egypt, told Reuters the discussions were "still very far from reaching an agreement about almost everything from a developing economy or emerging markets perspective."

While the target finance amount was important, Mohieldin said any deal needed more clarity over the types of financing to be offered, such as loans, equity or guarantees, and how it would be counted to ensure governments deliver what they pledge.

"Unfortunately, some of the major advanced economies are not really doing their fair share... there are many pledges that are not honoured," he said.

Brian O'Callaghan, an adviser to the United Nations Economic Commission for Africa, said he was concerned that the dynamic nature of climate impacts were not being accurately reflected in the discussions around the finance target.

"The number to me should be higher than a trillion per year," he said. "And then there's a question of how that number changes over time and honestly that level of sophistication has been completely lacking in these technical expert dialogues."

Stronger policies were needed to encourage cleaner technologies and to cut emissions in developed countries, delegates heard, echoing a new initiative launched at the start of the week.

Mission 2025, backed by leading companies, investors and cities, aims to encourage governments to set ambitious policies when submitting their next round of climate goals to the United Nations early next year.

"The main barriers to achieving the climate action we need is not economics, it's not technology, it's politics and institutional change," said Nick Mabey, founder of the annual event and co-Chief Executive of independent research firm E3G.

(Reporting By Susanna Twidale, Virginia Furness and Simon Jessop, additional reporting by Gloria Dickie; Editing by Ros Russell)