An increase in the number of whales with sunburnt skin has been documented by scientists after they took photographs and tissue samples of the animals.
In the worst-hit species – the blue whale – researchers found that the numbers affected rose by 56 per cent between 2007 and 2009, which they said has "worrying" implications for their health.
"Whales need to come to the surface to breathe, to socialise and to feed their young, meaning that they are frequently exposed to the sun," said Laura Martinez of the Institute of Zoology in London.
"It is not clear what is causing this increase. A likely candidate is rising ultraviolet radiation as a result of either ozone depletion or a change in the level of cloud cover."