Melanoma cases likely to decline

New Zealand could lose its unenviable reputation as the skin-cancer centre of the world thanks to climate change.

Extreme levels of ultra-violet (UV) radiation caused by clear skies and bright sunshine kill between 250 and 300 Kiwis a year, giving New Zealand the highest death rate from melanoma in the world.

However, there may be cause for celebration, with some scientists believing that by the second half of this century the rate will be falling.

Scientists think that climate change will speed up a recovery of the ozone layer over much of the world and block out more of the damaging UV rays.

The maximum value of the UV index which at this time of year can reach "extreme" levels of 12 over the South Island and 13 further north would drop by two or more steps under such a scenario.

National Institute of Water and Atmospheric Research scientist Greg Bodeker said the peak in the skin-cancer rate was expected about 2040.

Beyond that, increased ozone concentrations were likely to take New Zealand and the rate back to where it was in the 1950s or 60s.

"It's a good story, absolutely. We are already seeing ozone recovery over New Zealand," Bodeker said.

"Skin-cancer rates of today are caused by UV exposure 20 or 30 years ago.

"All the indications are that climate change will accele-rate the recovery of the ozone levels."

Some people were concerned that if UV radiation levels fell lower than so far experienced that might lead to vitamin D deficiencies, but that seemed unlikely, he said.