Urban heat island effect exacerbating summer heatwaves, study shows

Reflective surfaces, green roofs can lower temperatures in sweltering cities

The sweltering heat endured by major American cities is being fueled by vast swaths of concrete and a lack of greenery that can ratchet up temperatures by nearly 9F (5C) compared with surrounding rural areas, new research has found.

In the past month, Phoenix experienced a string of four days above 115F (46C) for the first time and Boston hit 100F for the first time in a decade. A deadly heatwave in the US north-west, which scientists say would have been virtually impossible" without human-induced climate change, baked Seattle at a record 108F, while Portland, where roads buckled and power cables melted in the heat, reached an incredible new high of 116F.