Mozzies will come up trumps but winter snow on the Tararua Range and Martinborough's famed pinot noir are under threat from global warming.
While leading Wairarapa winemakers say the region's top drop is safe for a while yet, climate scientist Jim Salinger is warning its days could be numbered as temperatures rise.
He said New Zealand just ended its second warmest year since records began in 1870 and last winter was New Zealand's warmest on record.
High temperatures were expected to continue this year and while individual years could experience a drop in average temperatures, New Zealand and the world would get warmer through the years, Dr Salinger said. It was a direct impact of gases increasing the "greenhouse effect", he said. By 2030 to 2040 New Zealand would be about 1 degree Celsius warmer.
Last year's average temperature was 13.03C, 0.84C above average. Some bugs - notably mosquitoes, which got knocked back by annual frosts - would thrive, he said. Water would be more likely to fall on the Southern Alps as rain, rather than snow, and run straight off in winter. Snow that settled would melt earlier, meaning less water coming down the rivers to the plains. Around the lower North Island, winter snow on the Tararua Range "may well become a thing of the past", Dr Salinger said. Wairarapa vineyards might have to switch from grapes that grew in colder climates - such as pinot noir - to varieties such as those now grown in the warmer Hawke's Bay, he said. But Margrain Vineyard winemaker Strat Canning, of Martinborough, was not concerned about his pinot noir grapes in the next five to 10 years.
Mr Canning, who was "not an absolute convert" that global warming existed, said that while pinot noir needed cold conditions, Wairarapa nights would have to get a lot warmer to make the variety ungrowable.
Ata Rangi Vineyard winemaker Helen Masters said it was simplistic to look at entire-year averages in winemaking.
Over winter months the vine canopy was growing but it was not until January till March that pinot noir grapes were going through "tannin development" - the crucial part in grape development.
The 2013 harvest was shaping up to be one of the best vintages in years, she said. Grape growers kept an eye on weather patterns.
As protection, Ata Rangi had long planted varieties such as syrah, cabernet and merlot, which were more suited to warmer weather. Temperatures would need to rise significantly to rule pinot noir out in Wairarapa, she said.
Federated Farmers president Bruce Wills said farmers would adapt: "You either adapt or you die." This century could see tropical fruits or rice grown in northern parts of the country, he said.
Better water storage was needed - dams that could store rain and send it down rivers in a steady flow through the year.
His own Hawke's Bay farm had "100-year variations" in 12 months last year, from the one-in-70-year drought last summer to one of the easiest winters he could remember.
Climate scientist Brett Mullan, of the National Institute of Water & Atmospheric research (Niwa), agreed global temperatures were rising due to greenhouse gases.
While Dr Salinger used 22 sites to reach his conclusion that 2013 was the second warmest on record, Niwa used seven sites.
They showed 2013 to be the third-warmest on record.
- The Dominion Post
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