Gamma-ray bursts could destroy the ozone layer which filters the ultraviolet rays of the sun. Ultraviolet radiation could destroy all plants and make living on the surface unbearable.

It’s not an extinction level event but it’s pretty ugly .

>>It’s not an extinction level event but it’s pretty ugly .

Depends on the intensity, duration, & proximity of the radiation.

http://en.wikipedia.org/wiki/Gamma-ray_burst#Rates_and_poten...