The climate crisis poses a “significant and growing threat” to health in the UK, the country’s most senior public health expert has warned. Speaking to the Guardian, Prof Dame Jenny Harries, the chief executive of the UK Health Security Agency, said there was a common misconception that a warmer climate would bring net health benefits due to milder winters. But the climate emergency would bring far wider-reaching health impacts, she said, with food security, flooding and mosquito-borne diseases posing threats. “The heatwave this summer really brought home to people the direct impact,” said Harries. “But it’s the breadth of the impact. It’s not just the heat.” Referring to the recent floods in Pakistan, Harries said the UK needed to build resilience to protect the population from the health impacts of extreme weather events. “Colleagues from Pakistan … are suffering from the impacts of flooding. They are dealing with stagnant water, higher risks of sewage overflowing into publicly accessible water spaces,” she said. “We are seeing in some of the things that could be happening in the UK.” The aim is not to paint a “doom and gloom scenario”, she added, but to identify threats for which the UK could prepare. Speaking at the UKHSA’s annual conference in Leeds this week, Harries launched a Centre for Climate and Health Security. She argued that the threat to health should be considered as part of the UK’s broader climate policy, including the commitment to bring greenhouse emissions to net zero by 2050. Even with action to limit climate change, “there is an in-built element of temperature advance that we can’t control”, she said, and that would require adaptations to protect health. This summer, the UK experienced record temperatures of 40.3C and six separate heatwave periods associated with more than 2,800 excess deaths. “If several aeroplanes all exploded and we’d lost that many people it would be front-page news in health protection terms,” Harries said. It is projected that numbers of heat-related deaths will triple by 2050, with the hottest summers on record that we have observed in recent years becoming simply “normal” summers. “That’s quite a near-term risk and so a priority for us,” she said. “There are things we can do about it, so we should act.” Unlike hotter European neighbours, such as Spain or Italy, the UK’s infrastructure is not designed to allow people to live and work in such conditions. “[Hot] European countries will routinely have air conditioning, they will have stone floors which keep the buildings cool. We don’t have that in the UK,” said Harries. “There is an absolute need to think through what our buildings are like going forward.” Lifestyle adaptations such as not going outdoors in the middle of the day in summer and longer summer holidays for schools might also have a role in future, she said. “We have much to learn from countries that currently have warmer temperatures,” she said. “If we’re going to be a hot country soon we need to be thinking the same way.” Viewed purely in terms of annual excess deaths, the climate crisis was likely to have an interim benefit in the UK due to warmer winters, Harries said. But other factors could soon reverse this trend. As temperatures rise, Europe is becoming vulnerable to infectious diseases historically seen in the tropics. The Asian tiger mosquito, which carries dengue fever and chikungunya, is now established in southern Europe and this year France experienced its most severe outbreak yet of dengue, which mosquitos can transmit efficiently only when average temperatures rise above 28C. “In France, they have had cases of infectious disease that you would normally see in tropical climates and the vector has come right up to Paris,” said Harries. “We’re starting to witness the progression of this impact in European countries. In the UK, Asian Tiger mosquito eggs have been detected in the south-east and the Culex modestus mosquito, which can transmit West Nile virus, is present in parts of Kent and Essex. “We’ve already beefed up [our surveillance programme], but it’s one of those areas where we need to raise the flag and build out capacity in advance,” she said.