Wine Growing in a Warming World

Could we be growing Cabernet Sauvignon in Kelowna or perhaps even Carignan?

That may be possible one day, according to Dr. Greg Jones, the Director of the Evenstad Center for Wine Education and Chair in Wine Studies at Linfield College in McMinnville, Oregon.

Jones says global warming will bring changes in crop mix to wine regions all over the world, including BC’s Okanagan Valley.

“In a cool climate region, a one degree celsius increase in the average temperature can change the location at which a grape varietal can be grown successfully,” Jones told the 2019 Enology and Viticulture Conference in Penticton in July.

“I always like to talk about Pinot Noir,” says Jones, explaining that the varietal needs a very narrow climate range to produce a high-quality product. “Pinot Noir has roughly a two-degree growing season climate niche and does best when average temperatures are between about 14-16’C.” he notes. “A cool year in Burgundy produces a lighter style wine, while warmer years bring out bolder characteristics.”

Jones adds that while you can grow Pinot Noir in a cooler area, it may not be ripe and in a hotter area it may be over ripe and headed for the bulk wine bin.

For example, Jones says a three degree increase in the average temperature in Oregon’s Willamette Valley would transform the noted Pinot Noir region from Burgundy to Bordeaux style wines.

“We know that as climate structure changes over time, it really influences suitability,” Jones says. And it’s not just a latitude shift he adds. “Grapes will be grown in more northerly regions, but also at higher latitudes and broader coastal locations.”

Regardless of your thoughts on the cause, the earth is warming, Jones notes. “The earth is warmer now than at any time in our recorded past,” he says, and continued warming is highly likely. “Along with that, models tell us there will be increasing variability and extremes in our weather as well.”

What does that mean for grape growers? Jones points out that wine grapes are some of the most difficult crops to grow successfully. “Viticulture is a very complex system where all plant growth stages need to work successfully for good wine grape production.”

The increase of 1-2 degrees Celsius in the average temperature that has occurred in the last 50-100 years in wine regions globally, impacts the industry in a number of ways Jones says. We see changes in cool season chilling, which may lead to a lack of dormancy for vines. There are increasing impacts of heat stress on vines, which will affect grape quality. A warming atmosphere raises humidity and disease pressure, increasing challenges for growers. And sugar, acid, phenolics and flavours, grow out of balance, leading to a change in wine style. Jones notes there has been a 2 to 2.5 % increase in alcohol content in wines globally since the 1950s. These are all indications that the suitability of a variety to a particular region can change over time.

“To look at it simplistically though, somewhere between a simple measure of too cold or too hot there is a sweet zone for a variety,” Jones says. But are we able to manage vines differently or is there some ability for a variety to expand its capability across a climate threshold?

The industry needs to look at more genetic potential, Jones argues. “We have a tremendous genetic potential within Vitus vinifera and I think we are a bit too narrow,” he says. “Understanding how varieties perform in other places, may help the industry breed new varieties in the future.

“We also really need to understand landscape potential for adaptation,” Jones adds. For example, he points out that planting on a south facing slope may not be the best thing to do in the future, when that region sees a lot more heat. Training systems, canopy geometry, row orientation and shade materials all become important in areas experiencing higher heat stress and overall climate stress. “We also need to understand root stock and scion combinations, so we can really understand that connection between soil and climate,” he says. “And lastly I think grape wine water use efficiency and irrigation management will become more critical as we get into a hotter and drier world.”

Jones notes that while there is a great diversity of wine grape varieties across the world, the industry does not have much knowledge on how they can perform across different climates.

“We tend to focus on what is marketable and I totally get it,” Jones says. “But we need to focus on those other varieties, so we can match them to the climates that we are going to see, not only today but in the future.” ■