UK heatwaves this year may have cost economy £4.4bn in lost output

Green think tank Verdant has revised upward its estimate of the economic toll from this summer's UK heatwaves. Having previously put June's cost at £2.36bn, the organisation now calculates that adding July's extreme heat brings the total loss in output to £4.4bn.

These losses stem from workers becoming less productive during hot spells, along with infrastructure and equipment overheating and needing to be shut down. Verdant's director, James Meadway, said the economic costs of climate change are already being felt and will keep growing, arguing that government action to shield workers and businesses from extreme heat is overdue.

This week the Met Office issued an amber warning for extreme heat in England, marking a fourth heatwave following episodes in May, June and July. Forecasters say the UK is on track for its hottest summer on record.

Verdant is urging ministers to set a maximum workplace temperature and to prepare a compensation scheme for workers forced to reduce their hours because of extreme heat. The think tank also calls for investment in redesigning towns and cities to include more cooling green spaces.

The estimates leave out indirect costs such as wildfire-fighting expenses or extra electricity use from fans and air conditioning. Verdant says the impact has likely been greatest in London and south-east England, where temperatures have been highest. Should heatwaves keep intensifying at the pace seen over the past decade, the annual cost could exceed £25bn by 2030.

The figures draw on cross-European data from insurer Allianz, which finds worker output per hour falls by 3% for every degree above 30C. This aligns with separate research from the London School of Economics' Grantham Research Institute, which attributed over £1bn in lost output to June's heatwave alone. A survey by the institute found 3.6% of respondents did not work at all during the hottest week in June, while 87% reported at least one health impact, ranging from poor sleep to dizziness.

Nearly three-quarters of England has now been officially declared in drought. London mayor Sadiq Khan and TUC general secretary Paul Nowak have both urged the government to hold firm on climate targets and introduce stricter workplace heat rules, including halting work once temperatures reach 30C, or 27C for physically demanding jobs.