Using a state-of-the-art climate model, researchers now believe the level of ultraviolet (UV) radiation reaching the Earth’s surface could have been underestimated, with UV levels being up to ten times higher. UV radiation is emitted by the sun and can damage and destroy biologically important molecules such as proteins.

 

The last 2.4 billion years represents an important chapter in the development of the biosphere. Oxygen levels rose from almost zero to significant amounts in the atmosphere, with concentrations fluctuating but eventually reaching modern day concentrations approximately 400 million years ago. During this time, more complex multicellular organisms and animals began to colonise land. Gregory Cooke, a PhD researcher at the University of Leeds who led the study, said the findings raise new questions about the evolutionary impact of UV radiation as many forms of life are known to be negatively affected by intense doses of UV radiation.