Toronto, Sep 7 - Rapid climate changes are set to redistribute the already shrinking ozone layer, exposing earth's southern parts up to 20 percent more ultraviolet radiation, warns a Canadian study.

Concentrated in the stratosphere from 10 km to 50 km above the earth, the ozone layer protects life on the planet by absorbing more than 90 percent of deadly ultraviolet rays coming from the sun. Ultraviolet rays cause genetic changes and trigger various cancers.

Writing in Nature Geoscience on Sunday, University of Toronto researchers Theodore Shepherd and Michaela Hegglin warned that rising temperatures will change the circulation of the earth's upper atmosphere.

In their computer-generated model to highlight the impact of climate change in the next 100 years, the researchers said rising temperatures will cause a marked increase in the movement of ozone from the earth's upper to lower atmosphere.

As a result of ozone's climbing down, there would be less ozone in stratosphere (higher sphere) to protect humans from ultraviolet rays.

They estimated as much as 20 percent increase in ultraviolet radiation hitting high altitudes in the Southern Hemisphere in the spring and summer.

More ultraviolet rays hitting the Southern Hemisphere will also cause an upsurge in biological changes and cancers, the researchers said.