Winemaking in 10 years: How climate change is affecting Marlborough, New Zealand's largest wine region

The Marlborough has around 26,000 hectares of vineyard. Photo / 123RF

With 26,000 hectares of vineyards, Marlborough is New Zealand's biggest wine region - and still expanding by the minute.

The region at the top of the South Island is home to most of the vines that produced more than 296,000 tonnes of sauvignon blanc grapes last year and is expected to expand by a further 6800ha in 2019/20.

Marlborough, considered the engine of the wine industry, is now home to about 70 per cent of all vines and some 510 grape growers.

In total, New Zealand has about 700 wineries and more than 2000 individual vineyards. About 10 per cent of the wineries and 5-6 per cent of vineyards are certified organic.

However, climate change now poses a significant threat to this country's wine industry, says NZ Winegrowers chief executive Philip Gregan.

"If people don't embrace it and accept it as a reality, that will be a big, big problem," says Gregan. "But our industry accepts, and understands, that we've got to learn and evolve as the climate is going to change.

"We've seen heat spikes in the last few years that we haven't seen previously and strangely more rain in some areas.

"People are really starting to say is it climate change that's actually happening now at my front door? It's not something that may happen in five or 10 years' time, but I'm actually seeing the impacts now."

Over the next 20 years, the methods used to grow grapes and turn them into wine are going to change.

"The techniques and the tools we use in the vineyards to produce our grapes, they are going to have to evolve as the climate changes," Gregan says.

In that same 20 years, consumers' preferences will also have changed, he says, as they expect their wine to be organic and derived through sustainable means.

New Zealand's sauvignon blanc boom took off in the late 1990s, with an influx of vineyards beginning in the early 2000s. Since then, the sauvignon blanc market has grown rapidly, with sales and demand rocketing, particularly from the United States and Australia.

It is believed that New Zealand's warm days and cool nights retain the acidity in grapes, giving New Zealand-grown sauvignon blanc its unique flavour.

New Zealand wine exports for the year to June 30 totalled $1.7 billion, an increase of almost 3 per cent on the previous year. Sauvignon blanc accounted for about 75-80 per cent of that total, says NZ Winegrowers annual report.

Gregan does not believe the sauvignon blanc boom is about to peter out any time soon.

"In terms of global demand for sauvignon blanc, I see that continuing to grow, but our ability to supply will be constrained by land, so wineries will be very focused on how to achieve the maximum value out of their investment and that is inevitably going to mean changes in the way they market their products."

Villa Maria Marlborough viticulturist Stuart Dudley believes the wine industry will continue to flourish, despite challenges climate change will bring.

"The industry is still in growth mode," he says.

"We're still a young industry. We've had this huge growth in the last 20 years which is pretty short in wine-growing time so we are still learning. With that, things should be getting better, and I definitely think the best wines are still to come."

More frequent warmer weather, or extended rainfall, poses the risk of altering the flavour of grapes, so wine producers will become more reliant on science to combat the effects of climate changes in the years ahead, Dudley says.

"It is going to get warmer and it will affect the temperatures that we're growing our grapes, which may over time [affect] the varieties that we're growing. It may mean that some varieties that weren't suitable, as it was too cold, may suddenly become suitable. Hopefully those changes are so far away that they don't affect the style of something such as our sauvignon blanc, which we're very happy with."

The challenges aren't going to necessarily be any different, they might just be enhanced.

Associated with climate change, there is also the risk of more extreme natural events such as drought and cyclones.

"The key thing for us is to build more resistance into our farming systems," says Dudley, "and that's around the way we grow our grapes, making sure they are well set-up to be more resilient.

"We work on growing-degree days - a certain amount of growing days in a season, and having warmer temperatures definitely does increase your growing days.

"The reason cool-climate viticulture - which is what New Zealand is, that freshness and beautiful fruit flavour that we get, and the good acidity - is due to that long growing season ... so if grapes ripen quicker and you move that harvest season earlier, it could potentially change some of those profiles."

A rising temperature can result in more sugar in the fruit, and therefore higher alcohol levels.

"We're learning techniques around the use of water, exposure, yield management and how all of that can affect these flavours, so hopefully we'll be able to retain as much as we can."

Wine producers need to build resilience into their farming practices to weather the challenges of climate change, says Dudley.

Stuart Dudley, Villa Maria's Marlborough regional viticulturist. Photo / Supplied

"Make sure throughout the season you are ticking all of the boxes around disease management, so if we do have adverse weather events that you are managing your vineyard to become as resilient as possible. The flip side of it, as it gets really dry, people need to put in water storage so we're not reliant on our rivers.

"The challenges aren't going to necessarily be any different; they might just be enhanced."

Last year, Villa Maria experienced a lot of rain during its summer growing season and the year before that it had to cope with an extremely dry spring.

"Every season is different and that's part of cool-climate viticulture and always has been," says Dudley. "We do have very cold seasons and very warm seasons, it's just whether they start drifting in different seasons and change."

Dudley's definition of viticulture is a mix of science, art and the place where grapes are grown.

He says wine producers' reliance on science will increase as the affects of climate change heighten. "Dealing with challenges, I think science is going to be 75 per cent [of our approach]."

As well as Marlborough, Villa Maria has vineyards in Auckland, Gisborne and Hawke's Bay.