India, June 13 -- In the middle of an Indian summer, a tree can feel like a miracle. Step from a shaded avenue onto a treeless stretch of asphalt and the difference is immediate. The road burns, the air thickens, and the body seems to absorb heat from every direction. In cities such as Delhi, Kolkata, Ahmedabad, Chennai, Bengaluru and Hyderabad, this is becoming a public health crisis.

Indian cities are heating up for two reasons at once. The climate crisis is making heatwaves longer, harsher and more frequent. At the same time, the way our cities are built is trapping heat. Concrete, asphalt, glass and brick absorb heat during the day and release it slowly at night. This creates the urban heat island effect, where cities become hotter t...