The modern energy systems created during the industrial revolution have delivered some really massive public health gains -- from transportation to heating and cooling systems, to higher standards of living. But the energy that we have been using to fuel those systems is creating some really significant public health costs, Trevor Houser explains in this presentation to the Global Climate Action Summit. He highlights new research that is helping us see just how large those costs are. Climate-driven heatwaves alone have the potential to become one of the largest causes of mortality around the world in the years and decades ahead, and that doesn't include other climate-related health impacts like ground pollution or ozone. That's the global average and, like with many public health threats, developing countries are going to face the biggest burden. Fortunately, that hot, polluted future is not predetermined. We can still change course, and in doing so we have the potential to deliver some of the most significant public health gains that the world has ever seen.