PROPHETS of doom have another disaster to tout. If a large comet or
asteroid smashes into Earth, a searing “ultraviolet spring” would follow the
devastating “impact winter”.
An asteroid ripping through the atmosphere would ionise nitrogen and oxygen.
The nitric oxide that forms then destroys the stratospheric ozone that shields
us from damaging ultraviolet light. Dust thrown up into the atmosphere would
protect the surface for a while, but once it had settled, survivors would face
elevated ultraviolet levels that could suppress photosynthesis and damage DNA,
says Charles Cockell of the British Antarctic Survey.
Other researchers had suggested that impacts…
