UK cities face rising heat vulnerability, with Portsmouth most at risk
Ordnance Survey research identifies Portsmouth as the most vulnerable UK city to extreme heat, with Leicester, Exeter, Bristol, and Nottingham also at high risk. The index shows that by 2040, all 71 cities in Great Britain will reach high heat vulnerability. Urban areas with less green space and tree cover are most affected by the urban heat island effect.
The heat vulnerability index, developed by Ordnance Survey alongside the Met Office and 4 Earth Intelligence, evaluates 71 royal charter cities across England, Scotland, and Wales. It projects that by 2040, every one of these urban centers will reach high vulnerability, with nearly two-thirds potentially facing the most severe category by 2100.
Portsmouth's most exposed neighborhoods, including Somerstown, Portsea, Southsea, and Fratton, feature sparse greenery and dense hard surfaces, often overlapping with areas of socioeconomic deprivation. Meanwhile, the City of London possesses the most extensive built environment and the weakest natural cooling capacity, illustrating how dense infrastructure exacerbates the urban heat island effect.
This research could significantly influence urban planning and public health strategies across Britain. Municipalities may need to prioritize tree planting and green infrastructure in deprived areas, as heat exposure disproportionately affects vulnerable populations like the elderly and those without air conditioning. Rising urban temperatures could also strain energy grids and emergency services during heatwaves, potentially prompting local authorities to reassess building codes and cooling centers. The projected rise in vulnerability suggests proactive adaptation measures will become increasingly essential for city resilience.