The financial impact of climate change is growing rapidly as worsening mega-storms, floods and droughts claim lives and batter populations around the world, according to banking experts.

But getting trillions of dollars in cash to the projects that can quickly make a difference - from electric vehicles for Mexico to big-scale solar power for India - remains hugely challenging, they say.

This is largely because most of the plans individual countries have drafted in accordance with the 2015 Paris Agreement to cut their emissions and make themselves more resilient to climate change are not, at this point, much more than lists of potential projects.

“You can’t invest in one of these plans,” warned Chris Dodwell, head of international projects at Ricardo Energy and Environment, a consultancy that advises the UK government on climate policy.

Turning the proposals into detailed investment plans that financiers can back - and that can begin changing perceptions among bankers about what a good investment looks like - is key to shifting billions into climate-protecting efforts, he and others said.

“We’re confident the money is available at the scale we need it,” said Ed Wells, a sustainability expert and head of global markets policy at HSBC Bank in London.

Right now, “the supply of projects is what’s short, not the supply of money,” he added.

To kick-start a bigger pipeline of investment-friendly climate projects, international bankers and officials from Mexico, Nigeria and Colombia are meeting in London this week to attempt to thrash out a first set of ready-to-fund climate projects.

Vietnam is also participating in what’s being called the Climate Finance Accelerator effort, although only as an observer.

The aim of the meeting is to smooth obstacles in the way to getting funding flowing, and give country officials the chance to hammer out a template for finance-luring projects that can be replicated at home, and potentially used by other countries as well, Dodwell said.

“You can’t green the whole world at the same time. Let’s start with the four countries here today,” he said on Monday at the launch of the week-long effort at the London Stock Exchange.

Juan Carlos Arredondo, who works on climate change policy for Mexico’s environment and natural resources ministry, said his country needs about $135bn to meet its aim of reducing emissions by at least 22 per cent below expected “business as usual” levels by 2030.

That would pay for initiatives such as shifting the country to electric vehicles - including Mexico City’s huge fleet of taxis.

The Colombian government wants to protect its Andean water supplies, get farmers better climate information to keep growing in harsher conditions, protect forests and make the country’s energy supply and transport systems cleaner.

But “we realise that with only public finance we won’t be able to meet our commitments,” said Lina Marcela Penuela of the country’s Ministry of Environment and Sustainable Development.

Making the kind of changes needed around the world could cost $90 trillion (£68 trillion), said Roger Gifford, chair of the Green Finance Initiative: an effort to make London a leader in climate-friendly lending and investment.

But Wells, of HSBC, said two-thirds of that is already potentially available, in the form of private investment looking for good projects.

“Most of the money is there if we can just create the structure to let it flow,” he said.

Political and market changes - from ever cheaper solar energy to announcements by countries such as China, France and the UK to rapidly phase out petrol and diesel vehicles - are helping more investors and bankers see opportunities in a green shift, Wells said.

“Financing the transition to the low-carbon economy is possibly the biggest opportunity (HSBC) has ever faced,” he said.

More investors also are insisting on knowing the climate-related risks faced by companies they back, said Stephanie Sfakianos, head of sustainable capital markets at BNP Paribas.

As realisation of those risks grows among investors and bankers, “it’s a game changer” in terms of where money will flow, she said.