An expert discussed the effects of a gamma-ray burst (GRB) from a supernova would have on Earth. He said getting hit by a GRB would most likely destroy Earth's ozone layer.
GRBs are produced by supernova events or the explosion produced by a dying star. Since these are extremely energetic explosions, they are often referred to as one of the cosmic dangers that can destroy Earth.
Destroying The Ozone Layer
Fortunately, since supernova events and stars that might go supernova soon are very far from Earth, the planet is still relatively safe from the full effect of a GRB. As noted by Duncan Caincross, a retired engineer from New Zealand, the worst effect that a faraway GRB would have on Earth could be the destruction of half the planet's ozone layer. Although this seems bad since it would expose half the planet to cosmic radiation, Caincross noted that it's not enough to kill all life on Earth.
"Some people think that a GRB could destroy the Ozone layer - and they may be correct - but that will only affect one hemisphere - and by the time that the depleted zone has spread the chemical reaction will have run its course and the ozone layer will be rebuilding," Cairncross explained on Quora. "Removing the ozone layer would not be an extinction-level event - some vulnerable species would go - but most would survive to repopulate once the ozone layer rebuilt itself."
Causing Mass Extinctions
However, if a star very close to Earth suddenly goes supernova and sends a powerful GRB towards the planet, the outcome would be very different. During such an event, the Earth's entire ozone layer would get wiped out. This means the entire planet would be defenceless against the radiation coming from space. Unfortunately, this is only one of the effects of a powerful GRB strike on the planer.
Aside from destroying the ozone layer, the heat generated by the GRB would be enough to boil Earth's oceans in a matter of minutes. Due to the extreme conditions brought on by the GRB, mass extinctions across different species would occur on Earth. Eventually, the planet would become completely uninhabitable due to the effects of a powerful GRB.