Paper finds that the amount of landmass on our planet that would be too hot for even healthy young humans (18-60-year-olds) to keep a safe core body temp will approx triple-an area almost the size of the US-if global warming reaches 2°C above the preind average https://www.preventionweb.net/news/half-degree-rise-global-warming-will-triple-area-earth-too-hot-humans