Five hundred million years from now, the Sun won’t be much larger than it is today but it will be swollen enough to start scorching the food chain. By then, Earth’s continents will have fused into a single landmass, a new Pangaea. As the Sun dilates, it will pour more and more radiation into the atmosphere, widening the daily swing between hot and cold. The supercontinent’s outer shell will suffer expansions and contractions of increasing violence. Its rocks will become brittle, and its silicates will begin to erode at unprecedented rates, taking carbon dioxide with them, down to the seafloor and into the deep crust. Eventually, the atmosphere will become so carbon-poor that trees will be unable to perform photosynthesis. The planet will be shorn of its forests, but a few plants will make a valiant last stand, until the brightening Sun kills them off, too, along with every animal that depends on them, which is to say every animal on Earth.