Analysis of tree rings of pink pines on the West Coast suggests global warming or the ozone hole is increasing the speed of growth of New Zealand's trees.
Meteorological records allow scientists to track changes in climate for about 150 years but tree ring analysis allows scientists to go back as far as 1000 years.
Dr Jonathan Palmer of the University of New South Wales said the pink pines study has told scientists that part of the country is in a period of warmer, drier weather unprecedented in 600 years.
He said current scientific thought is that the weather change is not due to global warming as such, but to ozone depletion in the atmosphere.