London Mayor Sadiq Khan has accused “climate action delayers” of costing lives and damaging the prospects of future generations.

In a speech on the environmental crises of climate change and air pollution on Thursday, Mr Khan highlighted how global warming is already hitting the capital, with soaring temperatures and flash flooding which closed 31 stations this summer.

And he warned things could get much worse quickly, with new climate risk maps for London warning that six boroughs faced very high risks of flooding and overheating.

A quarter of London’s railway stations, 10% of the rail network, one in five schools, almost half of hospitals and nearly 200,000 homes and workplaces in the city are at risk of flooding in the future.

He told the audience at the Barbican Centre there was only a small window of opportunity left to tackle the climate crisis.

“So I say to those climate action delayers, whether it’s nation states or the big corporations that financially benefit from inaction: you may say that we can’t move too quickly, that the necessary climate action would damage the economy, or that it’s not the right time to focus on climate change given the immediate challenges we face with Covid-19.

“But you’re wrong.

“Your slow response is costing lives right now, here and around the world, and damaging the prospects of future generations.”

He pointed to action on climate in the capital, including electrifying buses and taxies, scaling up solar energy, divesting pension funds from fossil fuels, skilling up Londoners for green jobs and investing in making homes and buildings more energy efficient.

And he said action was being taken to reduce air pollution that harms the health of Londoners and causes thousands of early deaths a year, including the expansion of the ultra low emissions zone to cut traffic fumes in the city.

But he said London could not take action on its own and urged the Government, as well as cities, businesses and governments around the world, to provide new funding and investment and devolve power to local authorities who would be delivering action on the ground.

Speaking to reporters after the speech, Mr Khan said Prime Minister Boris Johnson deserved credit for going to the UN and making a speech urging the world to take action ahead of the Cop26 climate summit being hosted in the UK.

“As hosts of Cop26 we’ve got a responsibility to show leadership, and it was important for the Prime Minister just to speak to the UN yesterday, I think, over the course of the next 40 days (until Cop26) having talked the talk, he’s got to walk the walk.”

He said there was no way the UK could meet its climate targets, including to cut emissions by 68% by 2030, without the PM working with cities, mayors and regions across the country.

“We want to be allies with the Prime Minister,” he said.

“Similarly you can’t disaggregate climate change from air quality, they’re interlinked, and that’s why it’s important to work with us in relation to giving us the powers and resources we need to make more progress.”

He called for more support to reduce transport emissions by helping electrify vehicles, and insulate and retrofit buildings across London and the country with low carbon heat pumps or heat networks.

In answer to those who say going green costs a lot of money, he said it was a good way of showing what the future of the country would be post-Brexit, with high-skilled, well paid jobs and a green economy.