If you think climate change is scary now, wait a couple billion years. In a new study, scientists estimate that the rising temperatures will make the Earth completely uninhabitable within 1.75 billion and 3.25 billion years, the Guardian reports. And it has nothing to do with carbon emissions. The sun is simply going to "get progressively hotter, and there's nothing we can do about it," one scientist explains.
The study is based on the concept of the "Goldilocks zone," the band of space around each star that is theoretically the right temperature to support life. Stars naturally get hotter over their life cycles, and as the sun does, the Earth will cease to be in the zone. Mars, on the other hand, will be more comfortable than ever, so if humanity still exists by then, it should make for the red planet. (Read more Goldilocks zone stories.)