The UK government is facing increasingly urgent calls for action to protect people against the intensifying effects of the climate crisis, as the highest maximum temperature record for June was broken for the third day in a row.

With the country in the grip of the worst heatwave ever recorded in western Europe – a direct result of global heating – the chair of parliament’s environmental audit committee warned ministers of the urgent threat and said the UK was falling “far short of what is needed”.

Toby Perkins said a significant number of deaths were likely as a result of the current heatwave. Previous heatwaves have killed thousands. He also warned of “devastating” effects on hospitals, care homes and schools, as well as transport, water, food and IT systems.

Perkins demanded answers from the environment secretary, Emma Reynolds, on how the government planned to tackle overheating in buildings and for its views on establishing maximum workplace temperatures, prescribing air conditioning for vulnerable people and changing school timetables. Others have warned of the danger to children in baking classrooms and of losses of hundreds of millions of pounds to the economy.

The highest maximum temperature record for June was broken three days in a row this week, with a provisional temperature of 37.3C recorded in Santon Downham, Suffolk, after two earlier Friday recordings also broke Thursday’s peak of 36.7C at Merryfield, Somerset.

Perkins said: “This week parts of the UK are facing a level of extreme heat that was once unthinkable. The effects of such extreme heat can be disruptive and devastating. Economic productivity will be hit, but more importantly we will likely see a significant number of deaths as a direct result of the current heatwave.”

He added: “The evidence could not be clearer that extreme heat is an urgent threat to the UK. Yet the government is currently falling ‘far short of what is needed’, according to its independent climate advisers.”

The Climate Change Committee has warned for more than a decade that the UK’s plans to protect people from rapidly worsening extreme weather are inadequate. It estimates that 92% of existing homes will overheat within about 20 years. In May, the CCC said the UK was “built for a climate that no longer exists” and needed urgent changes to survive global heating.

Perkins said: “Taking action carries a significant cost. But the cost of doing nothing is far, far greater.”

Emma Howard Boyd, the chair of the National Heat Risk Commission, said: “This week’s extreme temperatures risk losses to the economy of hundreds of millions of pounds due to lower productivity and infrastructure failures. More concerningly, it will cause the deaths of hundreds of people across the country. This is not normal.”

She said the UK was poorly prepared to deal with these extreme heat events. “It is time for us to treat this growing threat with the urgency it requires and make ourselves much more resilient to these extreme heat events.”

More than 1,000 schools have been closed due to the heatwave. Analysis by the campaign group Global Witness found that the average temperature at 3pm on Tuesday was almost 33C (91.4F) in London and more than 31C in the West Midlands, East Midlands, south-east, south-west and east of England. It also showed that more than 1,200 schools were in areas where outdoor temperatures breached 34C.

Flossie Boyd, of Global Witness, said: “It’s frightening to think of teachers and pupils trying to work and learn in swelteringly hot classrooms. This heatwave is a reminder of why we need climate adaptation now – to cool down our schools, and keep children safe.

“Investment in climate-friendly cooling measures, renewables that don’t heat our planet, and shade for our playgrounds, is vital. These measures should be funded by taxing the fossil fuel polluters who drove this extreme heat crisis.”

Hospitals in England have declared critical incidents as medical equipment and IT failed in the heat and sleep-deprived staff worked on sweltering wards. The heatwave has also caused a surge in admissions and people arriving at A&E, causing severe overcrowding in some places.

The climate minister, Katie White, told MPs on Wednesday: “If anyone still thinks that climate change is a problem for tomorrow, they should step outside today. We are upgrading transport, upgrading industry and upgrading infrastructure that in many cases was designed for a different century and a different economy.”

In response to the letter from Perkins, a government spokesperson said: “We are working across government to carefully consider the Climate Change Committee’s latest recommendations [from May] in relation to climate adaptation.”

The spokesperson said the government was already taking action by investing in clean power, ensuring new homes were designed to minimise unwanted heat and launching an adaptation advice service for local authorities.

The national adaptation programme published in 2023 was described by experts as “very weak”.

Perkins said: “It is imperative that the next iteration – due in 2028 – truly is a step change if we are to avoid the worst of the impacts from a changing climate.”