A billion new air conditioners will save lives but cook the planet

Summer in India has always been hot. Increasingly, it's testing the limits of human survival. As temperatures have climbed across the world's most populous nation in recent weeks, more than a dozen people died at an event in central India and thousands crowded hospitals with heatstroke symptoms. Hundreds of schools were closed and the mercury is still rising: Temperatures will hover around 45C (113F) across the northern plains this weekend.