The Waipawa River in southern Hawke's Bay during Cyclone Gabrielle. The cyclone was "definitely made worse because of climate change", Renwick says. Photo: RNZ / Angus Dreaver
A senior climate scientist says New Zealand may be relatively insulated from the extremities of future weather changes, but is urging the government to look at its implications, including the possibility of huge immigration numbers.
Victoria University's senior climate scientist, Professor James Renwick, told Afternoons New Zealand's temperate climate meant the country would not be affected as intensely by global warming and associated chaotic weather patterns as other nations, including neighbours Australia.
However, the author of new book Under the Weather A Future Forecast for New Zealand warned Aotearoa still faced climate chaos caused by out-of-control carbon emissions.
Cyclone Gabrielle, which wrecked havoc across the North Island earlier this year, was a recent example, he said.
"I think it will take longer for the extremes of climate change to really be felt here, compared to other countries that are more exposed to those extremes," he said.
"Australia's a good example of that. It's closer to the equator, it's hotter, it's drier. And so you don't have to push the climate there so hard to get extremes that are difficult to adapt to, such as the big fires that hit a couple of summers ago.
"New Zealand is less likely to see those extremes so quickly. So we will be I think, a bit of an oasis region in terms of climate change for a while. But if you push the climate hard enough, it'll become pretty difficult to deal with even here. But, assuming that we do get on top of emissions reductions soon, this country may well, comparatively speaking, be doing all right."
Renwick, however, said this was not necessarily all good news for the country, as it operated in a global community and would face external pressures.
"A lot of people around the world are going to look at this country and think, 'oh, would be quite a good place to go to avoid some of these extreme events we're experiencing where I live'.
"New Zealand is less likely to see those extremes so quickly" - Victoria University's senior climate scientist, Professor James Renwick
"We might have a lot of people who want to come here to live to get away... So how we deal with that, how that plays out, I think as an important issue - whether we end up with a much larger population because we are this climate change oasis. I'm not entirely sure. But there are consequences of being a country that doesn't feel the effects of climate change quite so intense as some others."
Another important issue facing New Zealand will be insurance companies pulling out of areas prone to climate disasters, which Renwick said was now happened in other parts of the world.
In May corporate giant State Farm said home and business property insurance was not being offered for new customers in southern California, citing rising costs from raging wildfires and skyrocketing repairs.
"The same kind of thing is starting to happen here that, if you live in a place that is very exposed to say coastal erosion or river flooding, such as the kind of things we saw with Cyclone Gabrielle, insurance companies are probably going to be reluctant to keep covering properties that are very risky.
"That's a situation that needs to be certainly discussed nationally, and we need to find solutions that involve central government and local government and individual property owners around who pays for the cost of this kind of thing."
Renwick said global warming was accelerating due to the amount of greenhouse gas emissions accelerating, with the rate of warming definitely going up in the last 30 to 50 years.
"I'm hoping that that rate of rise will start to slow down - we really need to see emission reductions happening and and we just need to take our foot off the accelerator pretty much, literally, to see the rate of change of extreme starting to ease off," he said.
Victoria University's senior climate scientist Professor James Renwick has released a new book charting weather changes in New Zealand. Photo: Supplied
The incremental changes introduced by the government demonstrated an incredible lack of urgency, even with recent initiatives like the introduction of the Climate Commission, he added.
In terms of the overall climate system, he did not envisage passing any thresholds or tipping points through the century that would suddenly make it an awful lot warmer or, or a lot more extreme. It would just gradually get worse over time.
It was a fact climate change was behind with the significant volumes of rain brought by Cyclone Gabrielle, he said.
"It was definitely made worse because of climate change. We've had one study of this already and way more to come, no doubt.
"The main thing that happens with cyclones or storms generally is that higher temperatures mean more moisture, more water vapour in the air, so you've got more fuel for rain events. When you have a storm that water vapour gets condensed out, rains out and if you've got more water vapour to start with, you're going to get more rain coming out of the sky on average...
"So we know that the amount of rain fell out of Cyclone Gabrielle was partly as a result of climate change and of course the energy released when you condense all that water vapour and create the rain feeds the storm, so the intensity of the storm went up because of that as well."