Four in five UK cities are ‘already highly vulnerable’ to becoming ‘urban heat islands, where their density of buildings and roads absorbs solar heat during the day, analysis by Ordnance Survey is warning.

Unlike rural areas, which cool rapidly after sunsight, cities retain their heat overnight creating pressure on people’s health, transport links and productivity.

Heat islands are set to intensify in London and cities such as Portsmouth, Leicester, Exeter, Nottingham, Brighton and Bristol.

Almost two in three are set to reach “severe heat vulnerability” by the turn of the century the analysis warns.

It found that 83% of Britain's cities (59 cities) are already highly vulnerable to urban heat, with the remaining 17% (12 cities) classed as moderately vulnerable today.

By 2040, rising summer temperatures are projected to push every city into the high vulnerability category, and by the turn of the century 63% (45 cities) are set to cross into severe heat vulnerability, the most serious level in the Index.

“These findings matter because cities are where millions of people live, work and spend their everyday lives,” said Ordnance Survey chief executive Nick Bolton.

“Extreme and sustained heat can affect people’s health and wellbeing, how comfortable our homes and workplaces are, and put additional pressure on transport, energy and emergency services.”

He added that the report is critical for planners, developers and local authorities preparing for a warmer future."

Last month a report published by Mayor of London Sadiq Khan and London Councils, which represents Boroughs in the capital, detailed the expected damage and strain on businesses, homes and public services due to extreme weather conditions.

It found that climate related damage could cost London up to £36bn a year by the 2050s.

Also last month a report released by think tank Verdant warned that successive heatwaves between May and July have cost the UK economy at least £4.4bn.

Investment in cooling programmes, green urban design and a national maximum working temperature are among measures needed due to increasing temperatures, says the think tank.

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