Understanding climate’s impact on vineyards

by | Nov 2, 2020 | Article

Climatologist Greg Jones has become the face of climate change in the global wine scene. His research has garnered awards and has fine-tuned growing philosophies. WineLand chats to Greg over Zoom to help us better understand the impact of climate change on our vineyards.


We caught up with renowned climatologist Greg Jones over Zoom.


During the late 80s and early 90s, when Greg first started his dissertation, he focused mainly on better understanding the role weather and climate played in vine growth, fruit production as well as wine characteristics. As he started delving into the data in Bordeaux, it was evident that trends in climate were already prevalent back then.

While the media was interested in Greg’s work, many in the industry were not so convinced and even outright deniers of what the data was saying. Fast-forward to today, and it’s a very different story. “Yes, we were using rudimentary climate change prediction models back then. But they were nonetheless, very accurate, and not far off from where we are today.”

With more advanced models at their disposal, modern-day climatologists’ ability to measure the earth’s surface and atmosphere is just tremendous. And these models are improving yearly.

Greg says if these models are accurate – and they’ve been pretty darn close within the range of uncertainty – then we’re looking at an increase of between 0.5 and 1.2 degrees Celsius in the earth’s surface temperature by 2035.

Greg and fellow climatologists predict that with 2019 and 2020, there’s a 99% probability that it could be the top one or two warmest years on record globally. “We continue to have one year on top of another of being the warmest on record. The system is telling us something. We’re not only experiencing changes in average temperatures, but changes in extreme weather patterns as well.”

He refers to high heat extremes (heat waves, droughts and bushfires), but also precipitation changes where there’s been either enhanced drying in some places or more extreme rainfall events in others.

We all know that with agriculture, it’s pretty straightforward and climate-driven. Weather produces risks and climate produces suitability and productivity. These are challenges every farmer will understand. But Greg says climate’s impact differs from what he calls ‘large-acre crops’ (corn, wheat and rice) and speciality crops (avocados, cacao and wine grapes), which are grown across much smaller geographies.

“But when you look at these speciality crops, they have a tendency to be more sensitive to change, because small changes can mean big things to a crop system.”

According to Greg, most wine-producing regions are located mid-latitude and most of the prominent viticulture regions in the world all have dry summers and wet winters. “These regions have finite climate systems for growing grapes, and with seasonal drought, these areas are often influenced by longer-term drought structures.”

Fluctuating temperatures a problem

Viticulture, says Greg, matches what we’ve seen globally. Growing seasons have typically been warmer. While some growing seasons still see frost events occur, they’re happening over a different kind of frequency and time period.

“Winters are still cold, but they don’t get as cold. Our summers have a tendency to have not only warmer conditions, but also more variability within the system.” He says temperatures in major grape-producing regions swing from 10 to 20 degrees Celsius to 35 to 45 degrees Celsius. “These wide fluctuations in temperatures are problematic, especially if they occur too close to harvest.”

In South Africa, grape-growers are learning to live with drought. Greg says in the Western parts of the United States, droughts are likely to occur more frequently and more severe in the future. “That’s because all of these areas that are mid-latitudes viticulture regions will likely experience drier summers and more wet winters.”

Rapid adaptation

Despite this, the vine – just like the average grower – is resilient and often adaptable to change. Greg agrees, but adds that the change in climate over the past 50 years has been more rapid than anything they’ve seen on record. “The big question is: Are vines adaptable within this rapid change? Yes, it’s a resilient plant system, but I think that as agriculturists, we need to ensure that we enhance the resilience of the system, both through managing the physical environment, but also the cultural environment. We need to be more adaptable as well.”

But how do we do that? Greg says growers and viticulturists must have a more sustainable approach and be more hands-on in the vineyard. “You know, I’ve always said, when it comes to wine production, the best way to be organic is to be in your vineyard, paying attention.”

He says if all you’re doing is sitting in your office or out somewhere trying to close sales, then you’re not managing your vineyard in a way that’s potentially more resilient to changes. “Being more sustainable has a broader perspective. If there’s better attendance, we have the ability to make our vineyards more resilient.”

Greg explains that when the atmosphere warms up, it has the tendency to have greater evaporative potential, which in essence, means that a warmer atmosphere can hold more moisture. But this doesn’t mean that the world will be wetter.

“In a warmer environment, we know that the atmosphere holds more moisture. Therefore, we have two issues that occur in drier climates. These areas can become even drier because the atmosphere demands more moisture, drying the earth’s surface and plant systems on top of that.”

The other issue, as Greg explains, is that if the atmosphere holds more moisture, it has the tendency to produce higher humidity which in turn could drive disease pressure, especially diseases that are problematic for viticulture (like mildew or rot).

Optimistic about green-mindedness

Greg has seen various innovative vineyard practices from growers around the world. “Growers who still like to maintain the VSP (vertical shoot position) with their vines, are installing cross-arm bars for instance, which increases shading around the fruit zone.”

“The creative things I’ve seen is not so much growers producing a U-shaped canopy, but rather a V-shaped canopy where the fruit zone still has a small amount of vegetation to protect the fruit, but not overwhelming, in order to decrease the risk of disease.”

We’ve seen a fair amount of sustainability and green-mindedness with growers in the field. Surely, this is a cause for optimism. Greg says there are several wine-producing regions that know that if they try to lift everyone up to be better stewards in the sustainability framework, then that entire industry will become more resilient.

“If those efforts become more important in the future, the culture and pride that comes from producing grapes more sustainable and environmentally-conscious, will be elevated to a more aware and resilient system.”


About Greg Jones: Gregory V. Jones is the director of the Evenstad Centre for Wine Education and holds the Evenstad chair in wine studies. He is a professor and research climatologist in the Department of Environmental Studies at Linfield University. He specialises in the study of climate structure and suitability for viticulture, and how climate variability and change influence grapevine growth, wine production and quality.

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