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New studies have confirmed that climate change is likely to bring New Zealand stronger winds, a wetter west and a drier east.
Niwa, the National Institute for Water and Atmospheric Research, is close to completing a series of climate change projections for the Ministry of the Environment. They are based on 17 different weather pattern models, and will replace projections from 2001, which were based on just six models.
Niwa principal climate scientist Jim Salinger said the research had found similar results to the previous scenarios.
"It's reassuring that the results are consistent, but there are also reasons for concern in that it is confirming that parts of New Zealand will get warmer but parts will also get wetter. [In] the bits that get drier, water will be a very important issue."
Scientists expect New Zealand's mean temperature will rise by an average 1.8C by the 2080s. By 2100, there will be up to 70 more days with temperatures over 30C, and frosty days will also drop, by five to 20 days in the North Island, and 10-30 days in the South Island.
Snowlines will rise and westerly winds will be 20 per cent stronger. Severe droughts are likely to occur up to four times as often, but heavy rain will be more frequent.
Niwa scientist Brett Mullan said the predicted range of temperature change matched the earlier research. In the 1990s Australian scientists had been forced to reverse previous climate change guidelines after studying new data, so it was pleasing New Zealand predictions were consistent.
"You don't really want to have to reverse what you were saying before, but there certainly were some differences from what we saw in the first assessment. I think we're on a firmer basis now."
East Coast farmers recovering from a severe drought can take some small comfort from the main difference between the old and new research: Dr Mullan said the east may not dry out as much as expected.
"However, there is still a wide range in terms of how much warming and whether it gets wetter in a particular season in the east of New Zealand or drier," Dr Mullan said.
Scientists could also not take into account the impact of any efforts to reduce climate change.
"If it does happen in a big way then the worst predictions won't come to pass after all," Dr Mullan said.
