An asteroid splashdown in one of Earth’s oceans could trigger a destructive chemical cycle that would wipe out half the ozone layer, according to a new study. The massive loss of protection against the sun’s ultraviolet (UV) radiation would likely force humans into a vampire-style existence of staying indoors during daylight hours.
The worst scenario based on an asteroid 0.6 miles (1 kilometer) wide would re-create the hole in the ozone layer, which appeared over Antarctica during the 1990s, except this would be worldwide. UV levels in the study’s simulation soared beyond anything measured so far on Earth by the UV Index’s daily forecasts of overexposure to UV radiation, and remained that way for as long as two years.
“An asteroid impact in the ocean is always dismissed as being a danger for coastal sites, but not much else has been discussed about it,” said Elisabetta Pierazzo, a senior scientist at the Planetary Science Institute in Tucson, Ariz. “I was looking at the asteroid hazard from climatic effects.”