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The numbers don’t lie. July of 2019 was declared by the U.S. government as the hottest month ever on record. Paris baked under a record 109 degrees during a sweltering heat wave that hit Europe in the beginning of the month. A weather station in Sweden inside the Arctic Circle registered 95 degrees shortly after. The years 2014-2018 were the five warmest years in the world ever recorded.

There is no mistaking that our planet is warming at an alarming rate. But while global warming generates a lot of headlines, its manifestations are more complex and nuanced. It affects different parts of the world, country and region differently; in fine wine producing regions, where the finicky vinifera grape varieties are grown, its impact could be especially grave.

In Napa and Sonoma, where droughts are almost an annual occurrence, climate change will make the area even hotter and drier. Or as one Napa vintner told me, “We are becoming Central Valley.” It’s no wonder that many Californian wineries have been investing in vineyards in Oregon and Washington for over two decades now. 

Regardless of their political stripe, farming folks are not climate deniers. They have been living the effects of climate change for years. To them, dealing with these effects has become part of their daily life. 

Suzanne Hunt, the president of Hunt Green LLC and a member of the Hunt Country Wines family that has been farming the west side of Keuka Lake for seven generations, said, “We are all very concerned about climate change. The last four years had been very dramatic.” She added, “Usually there’ll be a big weather event and you’ll have a few years to recover. Now we have two every year, more flooding, then a drought, polar vortex. And we now have Japanese beetle, stink bug and maybe spotted lanternfly, and this new horrible fruit fly that is attacking healthy fruit. It’s really daunting.”

Among wine drinkers, there’s an intense interest in how climate change will affect wine, especially rieslings, which the Finger Lakes are particularly well known for.  Through a series of interviews with wine and climate experts, the picture became clearer. Let’s start with the weather.

Oh, the Weather Outside is Frightful!

The Finger Lakes is getting warmer. But what does that really mean? Art DeGaetano, a climatologist at Cornell explained, “First of all, we are going to see steadily increasing temperatures, at night and during the day.” But the increase is not uniform. DeGaetano said, “In recent years, the trend is that there has been more warming at night than in the day, and more in the winter than the summer.”

A recent U.N. report projects the planet’s surface temperature will increase by 5.4 degrees Fahrenheit by the end of the century if humans do not intervene. That might not sound like much, but an increase of that magnitude could drastically change a landscape. 

“With just a degree or two Celsius change, New York could become southern Virginia in climate,” DeGaetano said. “The Finger Lakes might see the same amount of rainfall, but in bigger events. And the climate models show that most of the rain will occur during the shoulder seasons – spring and fall, so the summer will become drier and droughtier.”

Humidity in the Finger Lakes will also rise in step with higher temperatures, as warmer air can hold more water vapor than cooler air.

A common refrain we hear in the Finger Lakes these days is “extreme weather.” In the town of Lodi, on the east side of Seneca Lake, over 7 inches of rain fell in just a few hours on a day in August of 2018, resulting in devastating flooding that washed away roads, people’s cars and homes. The same storm dumped over 11 inches in Hector, just south of Lodi, over a two-day period. 

Our winters have generally become warmer. But our milder winters are still being punctuated by the extremely cold polar vortex periodically. While the mean temperature has risen by a degree or so, the temperature swings are becoming more pronounced.

Call it extreme weather or anything else, our climate is on the fritz!

Can Our Grapes Tough it Out?

Climate change brings a new set of problems and disruptions to the annual life cycle (phenology) of wine grapes. Their mitigations will mean a lot more work for growers.

Bud Hardening: As the temperature drops in the fall, grapevines begin a process called cold acclimation. The plant turns from green to brown and becomes covered with a waxy substance, which dries to an almost waterproof membrane, protecting the vine and its delicate buds. The acclimation process continues through the winter as temperature drops, further hardening the plant. The process is reversed in the spring, when de-acclimation commences, leading to bud break, when the vineyard seems to burst into green overnight.

Ideally, the hardening process works best when the temperature gradually cools down in the fall and winter, then gradually ramps up in the spring. With a trend toward warmer winters, bud hardening might not be as complete. Add extreme weather to the recipe, when temperatures could swing widely from day to day. The vine could get fooled by mother nature and stop hardening, then try to acclimate when it gets colder again. This stop-and-go process further weakens the vine and the buds.

Early Bud Break & Spring Frost: As the region warms, bud break has been happening earlier and earlier. Tim Martinson is Cornell’s state-wide senior extension associate, who advises vintners in New York state, noted, “Bud break records kept for a Cornell concord grape vineyard showed that bud break has advanced by a week since the 1960’s.” In some areas, the advance is 10 days or more.

Grape ripening has always been a challenge here in the Finger Lakes. If grapevines bud break earlier, wouldn’t that provide a longer growing season and result in riper grapes? The short answer is yes, but early bud break carries a huge risk – exposure to potential spring frost and hail damage. Once the tender green shoots appear from the buds, they become vulnerable to the cold if the thermometer dips below zero degrees. The combination of early bud break and extreme weather exposes the budding vine to a longer period of potential frost and hail danger. During the troublesome 2014 vintage, the Finger Lakes’ vinifera varieties lost 67% of their crops due to spring frost. If the cold is especially severe, it might even damage the trunk, resulting in the death of the vine.

Extreme Weather: DeGaetano considers warmer temperatures and heavy rainfall events as the two major issues defining climate change. High temperatures, especially when accompanied by a hot sun, could scorch or even split the berries. Hotter and drier weather generate more opportunities for heat stress, which affects flowering, berry growth, accumulation of sugar and ripening. Droughts has not been a serious problem historically in the Finger Lakes, but small summer droughts will become more prevalent as the region continues to warm. To compound the problem, most of our vineyards are not irrigated.

Large rain events present a different problem. In the Finger Lakes, shale and clay are commonplace, resulting in slow-draining soils. Some growers installed drain tiles when they planted their vineyards, but many did not. Even with drainage, soil erosion ensues when inches of rain fall within a short time. The loss of topsoil affects the vigor of grapevines, reduce available nutrients and potentially alter the pH of the soil – factors that lower the quality of the wine. 

Invasive Species: The Finger Lakes have been waiting with trepidation for the arrival of the spotted lanternfly. First discovered in Pennsylvania in 2014, the voracious herbivore has shown up in surrounding states, including a handful of dead specimens in New York. The Asian bug has no natural predators. The damage caused by it could be devastating. It targets anything, from fruit trees to ornamental plants to grapevines. In Pennsylvania, where 14 counties are now under quarantine, some vineyards lost as much as 90% of their crop in one vintage.

The Finger Lakes already is home to a myriad of destructive organisms – grape leafhoppers, spider mites, grape berry moths, and newer arrivals like Japanese beetles and the stink bug. Climate change will enable migration of more new species from the south. And current species could flourish and multiply in a warmer climate. 

Greg Loeb is an entomologist at Cornell who has done extensive research on the relationship between pests and viticulture. He explained, “We are seeing additional generations of grape berry moth over the past decade. Grape leafhoppers will more likely get two generations in during the summer as climate warms. Spider mites is another example. More generally, we might expect greater population levels and greater pest potential.”

Additionally, the added vigor of these insects will increase propagation of plant diseases, as some of them are vectors which spread diseases from one plant to another.

Fungal Diseases: Powdery mildew, downy mildew, black rot, botrytis and sour rot are fungal problems found in Finger Lakes vineyards. With few exceptions, they thrive in humid and shaded environments. With humidity expected to rise in our area, these diseases could become more rampant in the vineyards, requiring more mitigation.

Hans Walter-Peterson, a specialist with the Finger Lakes Grape Program of Cornell Cooperative Extension, recalled, “When I first started working here 11 years ago, downy mildew was not a big problem, but now it’s one of the biggest battles we have every year. Downy mildew is a disease that needs free water, either rainfall or heavy dew in the morning.”

Bacterial and Viral Diseases: Like humans, plants could be afflicted with bacterial and virus infections. If you drive around the Finger Lakes vineyards at harvest time, you probably see some of the leaves turning red. That is not part of their natural plant phenology. The phenomenon is caused by a viral disease called leafroll. 

“About two-thirds of Finger Lakes vineyards are infected with leafroll,” Marc Fuchs, a plant pathologist at Cornell who specializes in research of plant diseases, relayed. “It hijacks some of the key functions of the vine and could delay ripening of Cabernet Franc by three weeks, which is crucial because of our short growing season. There is no cure! The vines have to be replaced.” 

Fuchs also indicated that with warmer climes, other viral or bacterial diseases such as fanleaf and Pierce’s Disease could bloom in our region.

The traditional cold winter and cool summer night-time temperatures in the Finger Lakes have kept many of these diseases and vectors in check. With climate change, growers will have to deal with more disease pressures in the future.

The News is not All Bad

Climate change may well present a competitive advantage for our region. Compared to other wine producing regions in America, our warming has not been as severe. The Finger Lakes is still a cool-climate wine region, so we have more headroom to accommodate warmer climes than other areas. The historical vintage-to-vintage volatility has also made Finger Lakes growers accustomed to dealing with erratic weather better.

Our grapes will mature longer and better, creating riper and more complex wines, especially the reds. David Wolfe, a Cornell professor of plant and soil science, created the attached chart showing grape variety options for the Finger Lakes for the current, near term (2050) and far term (2080). It was based on research done by Greg Jones at the University of Southern Oregon. The chart shows that before long, a bevy of new varieties will become suitable for a milder Finger Lakes region. This presents new opportunities for growers in producing wines that are heretofore not possible. On the other hand, varieties such as pinot noir and gewürztraminer might become unviable.

Riesling chart

To see the future, we can perhaps look to the experience to-date of German rieslings from the Mosel region, a similar cool climate region. I had a chance to speak with Johannes Selbach, the owner of Selbach-Oster, when he recently visited the Finger Lakes. Selbach-Oster is one of the most renowned family-run estates in the Mosel in northern Germany, dating back to 1600. 

“The German winemakers are very concerned about climate change,” Selbach told me. “But it’s also exciting because there has been a change for the better, because grapes are getting riper. [...] Acidity is also getting riper, more buffered – the proportion of malic vs. tartaric acid has shifted towards a higher proportion of tartaric acid, which is more harmonious and integrated in the wine.”

What is a Grower to Do?

“The first thing a grower should do to make sure the soil is healthy,” Wolfe said. “Good soil health makes a farm more resilient and sustainable to combat climate change.” 

He also proposes that cover crops be grown between rows for erosion control and moisture retention, less tilling and the inclusion of more organic matters in the soil.

Growers will have to be more vigilant than ever against extreme weather events and pathogens. Unfortunately, they might have to apply insecticides and fungicides more frequently, bucking the current trend of reducing those usages. Other vineyard practices such as improved canopy management and new pruning strategies will help mitigate the effects from the rise of temperature and humidity. Be prepared to expect the unexpected.

And finally, perhaps the biggest question for growers – what variety to grow for the future. A vineyard is a long-term investment. Once it’s planted, it takes at least three years before it could produce fruit good enough to make wine. After 30 years or so, the vines will start producing less fruit, albeit maybe with more complexity in them. After that, productivity will decrease to a point that the vines eventually become economically unpractical. Planting the wrong grapes now translates to financial losses. Consider adding irrigation to the vineyard even though it might not be needed now.

Anna Katharine-Mansfield, associate professor of enology at Cornell, added, “Be flexible, be nimble. Invest in not just a diversity in varieties, but also a diversity of cultivars within a single variety. And be open-minded about changing the style of your wines.”

Help is on the Way

The science of winemaking keeps getting better. Katharine-Mansfield said, “We now have better understanding of controlling acidity and PH; understanding how flavors evolve. The better we understand these, the more we could control these compounds.”

Cornell’s Digital Agriculture initiative connects researchers from around the world to develop new data-driven tools to help farmers make real-time decisions. In a demonstration at a Finger Lakes vineyard this summer, tools were shown to automatically map soil content; map the canopy and differentiate among canes, leaves and berries; a machine that could count shoots and then a machine that thins them; and a machine that could count grapes to calculate crop load. New sensors are being developed to monitor light, moisture and temperature inside a grapevine’s canopy.

A new grapevine and fruit tree sensor designed at Cornell called the FloraPulse is in its final testing phase in California and is expected to be commercially available later this year. The device measures a vine’s water status, analyzes the data and makes irrigation recommendations. Another sensor in the works will monitor if there is surface water on the leaves, a pre-cursor to mildew formation.

John Martini is the owner of Anthony Road Winery and a board member of the American Grape Research Foundation. Martini described some of the projects the foundation is funding, “We need precision agriculture. How do you measure things better? Can you smell powdery mildew before you can see it? Can you build a device to detect and spray just the affected area?” 

FLX Rieslings 2

Riesling grapes

He is optimistic about the future, though. 

“In human history, technology has always come along to solve big problems. I think it will save us again,” he said. 

Organizations, state and federal governments are also pitching in. Sam Filler is the executive director of the New York Wine & Grape Foundation, “We funded some research at Cornell and other institutions to deal with new pests and diseases. In Albany, the governor just dedicated $2.4M for farmers to combat climate change.” Filler posited, “Question is if we are ahead of the curve or behind?” On the federal level, besides providing research grants on the issue, the U.S. Department of Agriculture recently announced that it will build a new $69M grape genetics facility on the campus of Cornell’s AgriTech in Geneva, NY.

Finally, political policy can make the biggest difference. The political will to reduce our carbon footprint might not reverse climate change overnight, but it will at least slow down its relentless march.

Speaking of Genes

Traditionally, new species of wine grapes were created either by natural crossings in the wild, e.g. chardonnay’s parents were pinot (as in pinot noir) and gouais blanc (not that distinguished), or via crossings made in the lab. Bruce Reisch, head of Cornell’s Grapevine Breeding & Genetics program at AgriTech, is also the project head for VitisGen. In a nutshell, VitisGen aims to identify genetic markers for traits such as disease resistance, cold hardiness and fruit quality. Those markers will then be used to inform and help speed up future crossing trials. 

Reisch’s other research includes ways to mitigate early bud break and other climate-related issues. He said, “Working closely with Jason Londo of the USDA Grape Genetics Research Unit, we are looking at the genetics of cold tolerance, trying to pick apart the plant’s system to understand how the grape acclimate, stay dormant and deacclimate so we can understand bud break better.” 

When talking about genomics, it’s natural to wonder about what CRISPR, the revolutionary gene editing platform, could do to improve wine grapes. Wouldn’t it be great to simply splice a cold-hardy gene into merlots to make them more winter-hardy? However, genomics is more complicated than just popping a new gene in an organism and expect a new and improved trait. There is much research to be done. Reisch explained, “We currently do not have the knowledge of which genes control certain traits such as waterlogging, cold tolerance. And many traits are controlled by multiple genes.” As for creating new grape varieties utilizing genomics, there is no shortcut. Reisch explained, “Technology will come along to help us do things better with greater efficiency. But the process cannot be accelerated that much, because there still needs to be multiple years of testing in the field, and in multiple locations as well.”

With the current intractable GMO controversy, where some of the arguments are not necessarily based in science, it’s hard to see how genetics could soon play a big role in alleviating the climate change problems faced by wine grapes.

The Bottom Line

So, there might be a renaissance of red wines in the Finger Lakes. But will our beloved rieslings survive? The consensus is that it would, at least for a few more decades. The riesling grape has the versatility to make good wine under a wide range of growing conditions. However, that bracing, vibrant acidity that is the signature of our rieslings will fade as warmer nighttime temperatures robs the grapes of some of their acidity. Inversely, the wine will become riper and perhaps more complex and balanced. There will be a new style of Finger Lakes rieslings. With some luck and elbow grease, it might even become better.

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