Harmful ultraviolet radiation has increased by 15 per cent since the late 1970s, according to a disturbing new study.
Scientists at the National Institute of Water and Atmospheric Research say the long-term increases in peak summertime UV radiation have occurred because of record levels of ozone depletion causedby pollution.
It is the first time a direct link between decreases in ozone and increases in UV radiation has been clearly measured, the scientists say.
Last summer the peak levels of sunburning UV recorded at the institute's laboratory in Central Otago were 12 per cent higher than a decade ago when measurements first began.
The team measured larger increases for UV radiation, blamed for damaging skin cells and plants, whereas levels of less harmful UV-A radiation, which is not affected by ozone levels, were unchanged.
The scientists' finding are published today in the journal Nature.
"These results provide the strongest evidence yet of man-induced increases in UV radiation in a region where baseline levels of UV were already high," said Dr Richard McKenzie.
"Based on these measurements and their agreement with model calculations, we estimate that sunburning UV has increased 15 per cent at this site since ozone depletion began in the late 1970s.
"This is significant as even relatively small increases in UV radiation can have a serious impact on human health, the biosphere and plants.
"For example, each 1 per cent increase in sunburning UV leads to increases of about 2 per cent in non-melanoma skin cancers."
Last night the Cancer Society said the findings were a warning for New Zealanders to spend even less time in the sun.
"Melanoma cases are very high in this country and kill 200 New Zealanders a year," said the society's chief executive, Jo Bransgrove.
"Skin cancer is the third highest form of cancer in women and fourth highest in men.
"If you must go in the sun wear a hat and use sun block."
Dr McKenzie and colleagues Brian Connor and Greg Bodeker said UV radiation in the Southern Hemisphere was more intense because of lower ozone levels and the cleaner atmosphere.
Also, in the Southern Hemisphere, ozone depletion happened throughout the year but in the Northern Hemisphere the depletion was less severe in the summer.
The team said that although the amount of ozone-depleting substances in the stratosphere were thought to have reached maximum levels, scientists were now concerned that the effects of global warming could delay the recovery of ozone levels by decades.
