Britain's canal network, built for coal barges, may have a second career as climate infrastructure. Researchers from the University of Manchester's geography, planning and engineering departments built a new energy balance model and simulated the thermal behaviour of more than 2,300 canal sections across Great Britain and Ireland over a full year, in what is described as the first national-scale assessment of how canals cool the streets around them.
The averages are modest but the extremes are striking. Daytime cooling near canals averaged about 0.8°C across the year, but rose to between 1.5°C and 2.3°C during heatwaves, exactly when relief matters most. Modelling of thermal comfort found hours of moderate heat risk fell by about 58 per cent and high-risk hours by about 74 per cent, with canals eliminating periods of extreme heat risk entirely in many locations. The study, published in Nature Communications, estimates urban heat regulation by canals is worth about 14.41 million pounds a year through avoided productivity losses.
There are caveats: water retains heat longer than surrounding surfaces, so canals cause slight overnight warming, and rising humidity near the water partly offsets the comfort benefit the cooler air provides. But as councils search for affordable adaptation measures ahead of hotter summers, the finding that an existing, centuries-old waterway network already delivers measurable cooling gives urban planners a rare piece of genuinely good news.