A major heat wave is forcing winemakers across the state to ask the tough questions, especially when it comes to their cool-climate grapes.
| The Golden State is more than worthy of its nickname as it bakes under another heat wave.
The California heatwave set records across the state this week, like 115 Farenheit (46.1 degrees Celsius) in the Russian River Valley, which is normally famous for its cool-loving Pinot Noir. In Mendocino County, the temperature reached 117 on Tuesday. 117! It’s Death Valley time.
Despite this, grapes are being harvested – mostly at night – as winemakers adjust to the latest curveball thrown by climate change. The heat will likely lead to a smaller crop, and that will force tough choices for single-vineyard winemakers.
“It’s going to be a vintage changer for California,” said Patrick Hamilton, winemaker at Notre Vue Estate Winery in Sonoma County. “For all the big companies – it was not planned, but the fruits that remain in the sun for several days at 110 degrees, they will be raisins. They will fall to the ground.”
Here is the good news. Kaan Kurtural, a viticulture specialist at UC Davis, said that while many individual grapes went through different stages of cell death on Tuesday (yikes!), wine lovers needn’t worry about the quality overall for Californian wines of this vintage.
“Producers are prepared to deal with these things,” Kurtural told Wine-Searcher. “They do a lot of things, like use shade cloths. They will irrigate before these events to put some moisture in the vines.”
However, you may see fewer single-vineyard California wines this year. Wineries not committed to wines from a single vineyard might want to blend grapes picked early, which have higher acid and lower alcohol potential, with grapes picked later, which have denser flavors. .
Martha Barra, owner of Barra of Mendocino, sent a snapshot of a thermometer reading 117 degrees in her cellar – the hottest it has ever been.
“I don’t remember it ever going over 110,” Barra said. “The grapes have stopped when it’s so hot. We did Chardonnay sugar tests this morning. The pH seems ok but the acid is still very high. My vineyard foreman said they didn’t have the taste of being ready.”
Barra said she expects to get high-alcohol Pinot Noir from her vineyards, but will blend it with Pinot Noir picked earlier. She had never picked grapes at night before, but this year the winery made a large light bar that spans three rows of vines to make that possible.
Barra, who has been farming organically for 33 years, recently became concerned about leafhoppers, a pest that can transmit vine diseases. This is another impact of climate change.
“My vineyard foreman says it’s because we don’t have cold winters,” Barra said. “Since it’s not so cold at night anymore, the little guys want to spend the winter with us. That’s probably our biggest problem with global warming.”
Sonoma County winemaker Kathleen Inman normally picks early; his wines like Endless Crush rosé are popular because they are understated. But she had a team pick grapes on Tuesday. She hadn’t planned to, but she ran into another contemporary California challenge: a labor shortage.
“I brought most of my stuff in last week. I have new projects with inexperienced growers who haven’t had all their harvesters lined up,” Inman said, as he was covered in grape skins. sticky in the heat. “Nine days ago I told one of the growers I wanted to harvest on Wednesday. Over the weekend he said everyone had canceled and he had no one to pick the fruit. You have to make a judgment about what things can expect by watering them down. . You have to take a calculated risk based on experience of what has to happen and what doesn’t.”
Inman chose to harvest clone Pinot Noir from Mount Eden, while leaving other clones in the same vineyard on the vine.
“This clone shrivels up if you don’t harvest it,” Inman said. “It tends to have a lot of little berries and those shrivel very easily. The sugar is much higher and when they soak up the rest of the juice, they increase the brix.”
Kurtural said the surface temperature of the grapes in the sun on Tuesday reached 60 degrees Celsius (140 Farenheit.)
“All of the desirable compounds for a wine grape are found in the skin of a berry,” Kurtural said. “It goes through different stages of cell death. The plant needs a lot more water to stay hydrated and sweat to cool it down. We started the year with a water deficit and we couldn’t catch up.”
Shade cloths are a temporary measure, but California growers will need to adapt their planting strategies for the future; many have already done so.
Kurtural said if you want to see how growers are adapting to climate change, watch out the next time you take State Route 29, Napa Valley’s main thoroughfare. Historically, the vines were parallel to the highway to better capture more sunlight.
“Now they run perpendicular to the highway to avoid sun damage,” Kurtural said.
Hamilton said that in Notre Vue, the most profitable grape variety is pinot noir, but he told owners not to plant more because of global warming.
“What scares me a bit is that nighttime temperatures are on average 8 degrees higher per night,” Hamilton said. “It will change the acidity of the grapes. We will have to change the grape varieties we grow. I told them that they should no longer plant Burgundy grape varieties. What we have, okay. But plant Rhône grape varieties. And in 20 years, plant grape varieties from Spain and southern Greece. Plant Grenache Blanc.
For now, however, wineries whose fortunes are tied to cool-climate grapes like Pinot Noir and Chardonnay can only fall asleep and wait for the heat wave to die down.
“What we’re seeing is just a rapid buildup of sugar in just three days,” said Scott MacFiggan, owner of Sosie Wines in Sonoma. “It’s a decision point. Either you want to get your grapes out before the heat peaks or you crush them and see what comes out the other side. It happened early enough in the season that the grapes wouldn’t aren’t ready to be picked. With our Pinot, we’re a little worried about whether it will go too far.”
But MacFiggan doesn’t plan to blend grapes from different vineyards together.
“We’re site and vintage-expressive,” he said. “So we’ll take it as it comes.”
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