Scientists are warning that politicians are failing to appreciate the magnitude of the climate crisis after The Met Office forecast that temperatures in the UK could hit 40C for just the second time since records began. Rare red warnings have been issued over extreme temperatures that are this week set to hit record highs for June – smashing the record set in 1976 by several degrees. The hot conditions will have major knock-on effects for health, schools, workers and transport, with experts warning that the predicted temperatures are “incredibly alarming” and should be seen as a public health threat. “Our first 40C day was supposed to be a wake-up call, but clearly someone hit snooze,” said Professor Friederike Otto of Imperial College London, referring to the last time the UK hit 40C in 2022.Follow our live updates on the heatwave HERE“Hitting 40C again - and in June this time - would be incredibly alarming.”Professor Otto continued: “There’s a sad inevitability to all of this, with scientists like me trotting out the same quotes year after year. Yes it’s climate change, yes it’s us, no it’s not El Niño.Current Met Office UK temperature forecast for 16:00 on Thursday 25 June (Met Office)”Right now, children are struggling to finish their exams in sweltering classrooms and the elderly are enduring dangerously hot homes and care facilities with little relief,” she added.“This heat is not an inconvenience, it is a growing public health threat. Every heatwave puts lives at risk, and it’s long past time we treated it with the urgency it demands.”The soaring temperatures, caused by human-driven climate change intensifying the impact of a “heat-dome” settling over western Europe, come as people gather for London Climate Action Week: a key fixture in the global climate calendar that is expected to attract 75,000 delegates from around the world, including heads of state and UN secretary general Antonio Guterres. Extreme heat warnings have been emailed out to delegates, while venues are ferrying in air conditioning units and encouraging attendees to drink plenty of water. Organisers behind a series of high-profile events happening at Mansion House, the official residence for the Lord Mayor of London that was built in the 1740s, said that the venue had upgraded its air cooling systems since last year and that there would be an increased provision of ice and soft drinks. But only so much can be done to cover for the fact that the buildings and infrastructure of the UK were not built for the climate extremes that we are experiencing today. A major new report warned last month that the UK is doing not nearly enough to adapt to the escalating climate crisis.The findings, which come from government advisory body the Climate Change Committee (CCC), include warnings that more than nine in 10 homes are not well insulated enough to keep out the heat. By 2050. we should expect a daily shortfall in water supply of five billion litres.UK ‘simply not built for these conditions’Bill McGuire, professor emeritus of geophysical and climate hazards at University College London, said temperatures of more than 43C are now possible in the UK’s current climate, with heatwaves lasting for multiple days.The country’s health services, energy infrastructure and transport are also “simply not built for these conditions”, he warned.“As 40°C+ temperatures become ever more common, expect many thousands sleeping in the streets as poorly insulated homes become uninhabitable heattraps, widespread power cuts as power cables sag and break, transport chaos as rails, overhead wires and signalling fail, and A&E departments overwhelmed by the old, very young, and vulnerable suffering from overheating,” said Professor McGuire. ‘Global warming is playing out’Richard Allan, professor of climate science at the University of Reading’s meteorology department, said that the current weather shows how “the global warming talked about when I was young in the 1980s is now playing out”, and added that much more must now be done to both decarbonise and adapt to our new weather. “A warmer atmosphere’s greater thirst for water also means more rapidly onsetting droughts but also the intensification of extreme rainfall and associated flooding as excess water drained from the soil and oceans is channelled into storms that can often be sparked off by summer heat,” he said. “Yet the solution to avoid further dangerous climate change remains unchanged – upgrade our industry, transport and agriculture to vanquish greenhouse gas emissions across all sectors of society.”Forecasters are warning that high humidity is set to make this heatwave particularly difficult to deal with. It is now widely expected that the current UK highest temperature on record for June will be broken by the end of the week, with 35.6°C having been recorded in Southampton in June 1976 and Camden Square in June 1957.