Shade That Travels

On hot afternoons, a shaded pavement can feel several degrees cooler than nearby asphalt. The difference comes partly from trees blocking sunlight before it heats roofs, walls, and roads. Leaves also release water vapour, which absorbs energy as it evaporates into the air. This process, called transpiration, cools the surrounding area, although its strength depends on available water. In tightly built districts, heat stored by concrete lingers after sunset, raising indoor temperatures overnight. Trees can soften that effect, but planting them is not a simple universal remedy. Where roots lack space, young trees may struggle, while dense canopies can obstruct airflow. Careful placement matters because shade is most useful where people walk, wait, and gather. As heat waves become more frequent, street trees are increasingly treated as public infrastructure. Their benefits are unevenly distributed, however, unless planting plans prioritize the hottest, least shaded neighbourhoods.