Beer & Wine Wine

How Winemakers Are Responding to Climate Change—in the Cellar

There’s only so much that can be done in the vineyards. The rest takes place during the winemaking process.

Smoky vineyard

Getty Images/Bloomberg Creative

Three previously unthinkable incidents so far during the summer of 2021 have put the severity of the new climate reality into stark relief: the high-pressure heat dome that roasted the Pacific Northwest, killing hundreds and shattering temperature records from California to British Columbia, the wildfires in Oregon that have been so severe they created their own weather patterns and sent clouds of smoke as far as Manhattan, and the devastating floods in western Europe that destroyed entire towns and killed at least 200 people. Even climate scientists who spend their days modeling dire climate futures based on current data have been shocked.

“The heat dome over the Pacific Northwest this summer was inconceivable,” says Tony Rynder, the co-owner and winemaker at Tendril Wine Cellars in Carlton, Oregon. “We’ve never seen anything like it, and I can honestly say we just don’t know what the ramifications will be for our wine. Actively modifying the way we make wine and making adjustments in the vineyard and cellar is becoming increasingly critical.”

Wine-growing is one of the most climate-dependent pursuits on the planet. A half-degree difference in average temperature can make a good vintage great, and vice versa; climate and data nerds can spend hours drilling down into the Köppen-Geiger classification system, mulling over the implications. Grapes also need water, but not too much. Fussier than Goldilocks, if not provided with ideal vineyard conditions, by the time they land in the cellar, the grapes can be unbalanced, flabby, oversweet, too alcoholic, and more, none of it good. 

While a lot can be done in the vineyard, including farming without chemicals, modified irrigation practices, vineyard floor management, canopy management, and harvesting earlier and at night to lock in freshness, producers increasingly are making several small changes in the cellar in a bid to edge each vintage slightly closer to perfection in an increasingly competitive and challenging market. These are the tactics some winemakers are using. 

Micro-Oxidating Fermenting Grapes 

Warmer vintages create wines with more alcohol, less acidity, riper structure, and riper tannins. In extreme cases, they produce flat and flabby booze bombs without character. 

Winemakers in the Napa Valley, a region hit hard by climate change, have been dealing with crop- and property-incinerating fires for the past several years. Some have taken to spraying sunscreen on their grapes and irrigating with disinfected toilet water. Many have been pushing back the harvest date each year and making subtle adjustments to their fermentation practices in the cellar. 

At Antica Napa Valley, winemaker Marla Carroll says her team “does some micro-oxygenation during fermentation and aging to soften our mountain tannins and integrate the fruit.”  

“After fermentation, micro-oxygenation is used to dose very small amounts of oxygen,” says Carroll. It helps by speeding up the polymerization of tannins, which stabilizes the wine’s color, she says, and allows the tannins to seem softer on the palate and more integrated with the wine. “I taste throughout the day and can adjust the amount being dosed by how the fermentation or aging wine is tasting.”

Adjusting tannins and mouthfeel, stabilizing color, and improving aroma integration doesn’t merely lead to a more pleasurable experience for wine drinkers with challenging vintages, but also increases the wine’s aging potential. 

Using Whole-Bunch Fermentation 

Grapes arrive at the winery just like they do at the grocery store, minus the plastic bags or clamshells: in piles of whole bunches, stems and all. While most winemakers opt to remove the fruit from the stem either by hand or (more frequently) with a machine, some winemakers ferment their grapes stalks and all. 

Making wine from de-stemmed grapes is generally thought to create a more elegant and less tannic profile, but whole-bunch fermentations are gaining traction for a variety of reasons. 

“It’s a whole category that has existed for decades and was popularized in Burgundy,” says Rynder. “It’s a way of building up wines with more oomph. I made my first whole-cluster pinot noir in 2011, and it was so successful, it has become a flagship wine. I’ve learned that sites with more marine, sedimentary soils produce grapes that are leaner, especially since we don’t irrigate. This makes them better suited for whole-cluster fermentation. And in warmer years, it’s a useful way to maintain freshness and floral notes. It also helps lessen the impact of severe grape dehydration, which can happen in very warm and dry years.”

Rodrigo Serrano, the winemaker at Domaine Bousquet in Mendoza, Argentina, concurs that especially during warmer vintages, that sense of fruit-forward freshness can still be achieved in the cellar. 

“Whole-bunch fermentation helped us achieve superior fruit expression in our malbec in 2020, and in 2021, we have tried with syrah, tempranillo, and malbec again,” he says. “We are learning that with malbec, it creates something very special, allowing us to achieve intense fruit notes.”

Wine grapes

Quinta do Ameal 

Adjusting Blending and Barrel Programs 

Using stalks and stems, which have high water content, in fermentations can, in addition to adding heft and power and delivering superior fruit expression, tamp down overweaning sweetness and lower a vintage’s ABV slightly. This is a “good option for warmer vintages, which have greater concentration, higher sugar content, and higher alcohol,” says Jose Luis Moreiro da Silva, the lead winemaker at Esporao Group’s Quinta dos Murcas in Douro and Quinta do Ameal in Vinho Verde, both of which are certified organic.

Da Silva says that in the cellar, he and his team also sometimes make adjustments to their red and white blends. Some grape varieties perform better in warmer years than others.

“We have the second-highest number of indigenous grapes in the world in Portugal, so we have dozens of grape varietals to work with at both wineries,” Da Silva says, noting that alvarinho, avesso, touriga France, and touriga nacional show incredible resilience in warmer and drier conditions. “In Bordeaux, they’re allowing alvarinho and touriga nacional to be grown and blended with their traditional grapes, which shows how useful they can be, even in very traditional wine programs.”

Da Silva also tweaks his barrel-aging programs in warmer years. “Some winemakers prefer to use new barrels that will compensate for some of the big flavors of warmer vintages, and I understand that,” he says. “But I prefer to use concrete. When I know a wine is going to have really big flavors, I find that it helps focus the wine and adds texture. In cooler years, though, I utilize barrels because with just concrete you lose that midpalate.”

At Chêne Bleu in the Southern Rhône, the team also “plays around with the specific blend of our wines,” says co-owner Nicole Rolet. “We prefer to deal with the grapes from a warmer vintage upfront during the fermentation process, rather than the aging process. So we typically conduct fermentation at a cooler temperature to keep the extraction levels down, and we adjust the blends. For example, in Le Rosé, we increase the percentage of vermentino in a hotter vintage, to 12%, from 5% in a normal year.”

Using Native Yeasts

For exclusively estate wine programs, warmer vintages can be especially challenging, as grapes cannot be sourced from cooler sites in their region. 

Goose Ridge Estate Vineyard & Winery harvests grapes from their estate vineyard in the Goose Gap AVA in Washington state, which means “our wines tend to strongly display an individual vintage’s unique characteristics,” says winemaker Andrew Wilson. “In warm vintages, the sugar accumulation can outpace flavor ripening, and the ripening can happen so rapidly, it’s logistically challenging to harvest all of the grapes at the perfect time.”

Harvesting earlier is essential, Wilson explains, but the winery also has ways to trick overly ripe grapes into behaving. “Commercial yeast has been selected to efficiently produce alcohol during fermentation,” he says. “We ferment combinations of different native yeasts to introduce inefficiency into the fermentation, which produces lower alcohol wines while building mouthfeel and adding complexity.”

Forgoing the Punch Down 

When grape juice ferments, bits of pulp, seeds, skins, and stem float to the top of the tank and form what is known as a cap. 

This cap contains a treasure trove of color, aroma, and body, so winemakers looking for heft punch the cap down either by hand, foot, or machine. The process can be dramatic and forceful, and has an outsize effect on how much flavor, color, and structure the final wine will have. 

In warm vintages, however, some vintners like John Grochau, the owner and winemaker at Grochau Cellars in Oregon’s Willamette Valley, swap out the punch down for a pump over, meaning the wine is pumped up from the bottom of the tank and splashed over the top of the fermenting must. “In warmer vintages, we find that it reduces bitterness and tannins if we do really gentle pump overs,” says Grochau.

Changing Styles

Another way to deal with climate change in the cellar is to stop fighting it. “We are always thinking about climate change, and the effect it has,” says Andrea Miotto, the winemaker at Azienda Agricola Miotto Lodovico in the Veneto region of Italy, who notes that in addition to rising temperatures, rainfall patterns have changed. “It changes the distribution of the rainfalls during the year. We can go from water stress to too much water very quickly. All of this has an influence on the acidity of the grapes. In recent years, we have been having lower acidities.” 

Acidity delivers that lively brightness that Miotto’s prosecco is known for. Without that acidity, the resulting wine is less sharp and dry, prompting vintners across the region to shift focus from extra-dry to brut prosecco styles. (Despite the name, brut is drier than extra-dry, with up to 12 grams of residual sugar per liter, while extra dry has between 12 and 17 grams per liter.)

“Lowering the sugar level balances the wine out, and it’s also the style the market is moving toward,” Miotto says. 

Delivering what the market is thirsty for amid increasingly unpredictable and difficult to manage weather conditions isn’t easy, but with a willingness to rethink and tweak techniques on the fly, it can be done.