A team of economists from universities in the UK, Mexico and the Netherlands have published an analysis in Nature Climate Change of the likely effects of climate change on 1,692 of the world’s largest cities.
They found that the total economic cost in cities this century could be 2.6 times higher when urban heat island effects are taken into account than when they are not.
The urban heat island effect occurs when natural surfaces, such as vegetation and water, are replaced by heat-trapping concrete and asphalt, and when heat from cars, air conditioners and other sources is added. This effect is expected to add a further two degrees centigrade to temperature rises due to global warming for the most populated cities by 2050.
Higher temperatures mean more energy is used for cooling, air is more polluted, water quality decreases and workers are less productive – all of which add to economic costs.
The researchers carried out a cost-benefit analysis of different policies for combating the urban heat island effect. The most cost-effective measure was found to the moderate-scale installation of cool pavements and roofs. Changing 20% of a city’s roofs and half of its pavements to “cool” forms could reduce air temperatures by about 0.8°C and save up to 12 times what they cost to install and maintain.