OS index examines which ‘urban heat islands’ suffer the most – and which cope the best with rising temperatures

Portsmouth, Leicester, Exeter, Bristol and Nottingham will be among the cities that warm the most by the end of this century as global heating turns British cities into urban heat islands, according to research.

Analysis from Ordnance Survey (OS) has created a heat vulnerability index for all cities in Great Britain. Portsmouth, which sits on the south coast of England and is home to 208,000 people, is the most vulnerable to extreme heat today and into the future, according to the research from the OS, the Met Office and the data analysis company 4 Earth Intelligence.