We hear a lot about global climate change these days, but the biggest threat to human life on this planet may actually come from a mass extinction. Are we currently facing one?
We know mass extinctions have happened at least five other times on Earth. Obviously, the dinosaurs all went extinct when an asteroid hit what we today call the Yucatan Peninsula. To qualify as a mass extinction, 90% of the planet’s species have to die off. By the estimates of some scientists, we’re currently losing 200 a day. Nonetheless, that still wouldn’t equal a mass extinction, even if we stayed on this current path. What worries some scientists is that we could be currently changing Earth’s atmosphere in a way that would start speeding up the process. Interestingly enough, something similar happened 2.4 billion years ago, when bacteria that were precursors to plants started producing massive amounts of oxygen, killing off much of Earth’s anaerobic bacteria.