When comets or asteroids crash into the world, they create global firestorms, massive tsunamis, massive global temperature fluctuations, and – most importantly – they can blanket the sky with soot and shut off photosynthesis, thereby killing off entire food chains.
The kinetic energy alone, however, is enough to make your head spin. The 10-kilometer-wide (6-mile) asteroid that finished off the already ailing non-avian dinosaurs released as much as 543,000 quintillion joules of energy. That’s 1000 times more than a day’s worth of hurricane, so already, asteroid impacts are ahead of the pack.
The most powerful impact event in Earth’s history involved a Mars-sized protoplanet named Theia crashing into it right at the start of the planet’s fiery birth – one ginormous enough to strip material off Earth that went on to form the Moon. This powerful impact released a mind-blowing 1 x 1030 joules of energy, equivalent to 1.84 million dinosaur-killing asteroid impacts. In terms of energy release, this event cannot be matched.
Mass Extinctions: Life’s Bottlenecks
So what about casualties? It’s worth highlighting that modern humans have only been around for 200,000 years of Earth’s 4.6 billion years of history. Even the most murderous natural disaster in human times will not even begin to match up to the most deadly, powerful events in the world’s ancient past – events called “mass extinctions”.
Mass extinctions are defined as prolonged periods of time wherein the global speciation rate remains far below the extinction rate. Although they are not really defined as “natural disasters”, they are complex beasts with always more than one cause, with each antagonizing force varyingly responsible. In many cases, scientists cannot agree which conspirator was the most culpable, so it’s worth taking them into account as mysterious smorgasbords of zoological destruction.
The five most clearly defined ones occurred between 443 and 66 million years ago with climate change, ocean chemistry fluctuations, trace element disappearances, massive volcanism, and asteroid impacts all to blame at various points.
Out of these, you might think that the famous asteroid impact that wiped out the non-avian dinosaurs (and almost all mammals and marine life) 66 million years ago would be the most “destructive”, and you’d almost be right. After all, it did wipe out as much as 75 percent of all life on Earth.
However, there’s a reason the end-Permian mass extinction 252 million years ago is referred to as the “Great Dying” – around 96 percent of all the world’s species were annihilated after prolonged, continental-scale volcanism from modern-day Siberia devastated the world’s climate. All living creatures we know today descended from the remaining 4 percent.
What of the other three mass extinctions? Well, most scientists agree that we are in the sixth right now, with species all across the world dying out thanks to our own species’ detrimental effects on the planet. The other two are fairly ambiguous.
Medium-sized asteroid impacts are enough to darken the sky and freeze the world. Mopic/Shutterstock