3. 800 Million Years From Now: Remaining Life Dies Out
Mass extinction doesn't, of course, mean that absolutely everything is dead. By this point, after the human race has been forgotten as the miniscule spot in history that we are, the Earth has still managed to be populated by some sort of life, which has adapted and evolved through countless dramatic changes in the world around it. It probably deserves a break from all this hardship, eh? Well, if it manages to get through that supernova that eliminates most things left living on the surface of the globe, then they do get to make the most of it for a good 300 million years. It's after that they need to start watching their backs. Because that's the point that carbon dioxide levels fall to the point at which C4 photosynthesis is no longer possible. Thanks to the volcanoes and ozone shenanigans the levels of carbon dioxide have been fluctuating wildly as it is, but it's 800 million years into our future that they're all but snuffed out completely. No if you'll remember your secondary school Science classes, you'll know that carbon dioxide is an important part in plant life existing, as well as an essential part of our atmosphere. Its disappearance not only precludes the continued existence of those few remaining plants, who have clung on for dear life for millennia, but also means that free oxygen and ozone also disappear from the atmosphere, killing off all multicellular life. All of it. 800 million years from now, the only inhabitants of the Earth will be single-celled organisms.
Tom Baker is the Comics Editor at WhatCulture! He's heard all the Doctor Who jokes, but not many about Randall and Hopkirk. He also blogs at http://communibearsilostate.wordpress.com/
