Changing rainfall extremes with climate change in New Zealand

INTRODUCTION
Heavy rainfall events occur when conditions force water-laden air to release its water. As the
climate warms the air holds more water vapour, with the potential to release an accordingly larger
amount of rain during extreme events. This document assesses the newest evidence1 on how warming
will affect extreme rainfall across New Zealand2.
We analyse data from three models3 of how the climate should change under human influence,
all slightly different in complexity, detail and size of dataset. Since each model has strengths and
weaknesses, agreement between models contributes to confidence in the accuracy of our predictions.
All three models have been run at various stages of global warming, ranging from a pre-industrial
climate, through the present day, to a range of warmer futures.