Why an Asteroid Strike Would Turn Humans Into Nightwalkers

Flattened cities, blankets of debris, earthquakes, tsunamis, wildfires, and shockwaves are just some of the ways a large asteroid impact could devastate life on Earth.

Now add depleting the ozone layer to that list.

A new model of asteroid smashes shows how a space rock plunging into the deep ocean would drastically alter atmospheric chemistry, leading to severe ozone depletion worse than anything in recorded history.

—Image courtesy Don Davis, NASA

Ozone is the name for the molecule made of three oxygen atoms, which can exist throughout Earth's atmosphere. Ground-level ozone is an air pollutant, and breathing it can cause serious respiratory issues.

But high-level, or stratospheric, ozone is the stuff that shields Earth from the most damaging types of the sun's ultraviolet light.

Holes in the ozone layer mean more of this harmful UV reaches the surface, and that can spell disaster for life—skin diseases, cataracts, and DNA mutations, for starters. Not to mention the damage "bad" UV can do to plant growth and thus the global food supply.

(Related: "Rocket Launches Damage Ozone Layer, Study Says.")

In the worst case seen in the new model, the amount of damaging UV hitting humans "would produce major sunburn" in just ...