Computer fine tunes forecasting 

A new computer model has taken the guesswork out of climate forecasting and is confirming what scientists suspected about how global warming will affect New Zealand.

Over the next  80 years we can expect to see increases in temperature, droughts and more extreme floods.

The big Manawatu flood was described as a one-in-100 year event, but scientists say over the next 80 years we are likely to see many more.

Climate modeller Sam Dean says New Zealand can expect "heavy rainfall events" and senior climate forecaster David Wratt says that has got implications "for planning where we build and those sort of issues".

British scientists predict temperature increases will see drought affecting half the world's land mass and its NZ's east coast that will bear the brunt.

"Much of New Zealand warms up by about 3-4 degrees and those changes are greatest in the southern alps due in part to a loss of snow," says Dean.

In the alps temperatures are expected to rise by up to seven degrees and the hotter conditions will be felt up the length of the country.

For Auckland that might mean that temperatures similar to what Sydney currently has or for Tauranga temperatures could be similar to the top of Northland.

The scientists say their computer modelling takes predicting the climate out of the realm of guesswork. The conclusions, based on conservative estimates of greenhouse gas, are not the worst case scenario.

"There are uncertainties in how the globe's economy will develop...in how greenhouse gases and still some uncertainties in the models. They're not perfect predictors," says Wratt.

But the experts say that knowing what is to come should help us plan how to deal with it.