July 26, 2013

Napa Valley, California

Napa Valley has often found itself featured in national newspapers and magazines as the paparazzied ‘poster child’ of climate change impacts on agriculture. Recent media coverage has been based on two studies: One 2011 study out of Stanford suggests the land suitable for premium grapes in Northern California could be cut in half by 2040, while vineyards might thrive in the Willamette Valley of Oregon. And a 2013 study led by Conservation International, published in the Proceedings of the National Academy of Sciences, predicts a two-thirds drop in production in the world’s major wine-growing regions, including Napa Valley.

The catch? Napa Valley vintners aren’t feeling the heat, both because the temperature signal hasn’t been strong (yet) and because they have a suitcase-sized toolkit for tackling most climate challenges that come their way.

Shedding the poster child image 

Napa Valley Vintners (NVV), a nonprofit trade association that has nearly 500 members, is the first to point out that, were some of the worst-case-scenario climate change impacts to come to pass—severe drought, coastal flooding, raging hurricanes, crop failures, etc.—“no one would care about where the best Cabernet Sauvignon is produced.” Indeed, a wine pairing wouldn’t be very relevant in a dried-up, burnt-out food system.

Still, many vintners understand why they’re getting so much attention. David Graves, the co-founder of Saintsbury winery, mused about possible headlines for other agricultural products: “‘Sorghum Population to Move 200 Miles North Along Great Plains.’ That’s not going to be above the fold,” he joked. “Wine grapes are sort of the charismatic mega-fauna of climate change.”

Grapes are also so climate-sensitive that the wine industry may act as a kind of ‘canary in the coal mine’ for other agricultural products. But the press coverage and the large-grained climate studies are not really useful for Napa Valley growers making day-to-day, year-to-year decisions on their land. So, after the first tales of wine apocalypse came out in 2006, the NVV formed a climate task force to find out what changes their growers are really seeing—and what they are doing to adapt.

“The very thing that makes premium wine grape growing happen is the very thing that often gets ignored [in climate studies],” Patsy McGaughy, the communications director at NVV, told us. That magic ‘thing’ is the specificity of Napa Valley’s climate. Nestled between the Mayacamas and Vaca Mountains, the valley is a unique mix of coastal and interior climates. The morning fog usually burns off by midday, but temperatures remain moderate.

Data from two weather stations in the valley show an average annual warming trend of 0.03 degrees Fahrenheit since 1931. Studies using this data say that minimum temperatures during the April-to-October growing season have increased by 2.9 degrees Celsius (5.2 degrees Fahrenheit). But the NVV says the locations of the weather stations are not comparable to the conditions found in a vineyard.

“At Napa State Hospital, the weather station is next to a paved road, an irrigated lawn and an air conditioner unit,” said Rex Stults, the NVV’s director of government relations. “In St. Helena, the station is atop the local fire house. I can’t think of another place in a wine region where a weather station should not be.”

The real climate story

In order to provide their members with more useful information, the NVV stood up a Climate Change Task Force, led by Dr. Dan Cayan at UC San Diego’s Scripps Institution of Oceanography. The group of researchers and vintners spent three years collecting data from 20 private and 8 public weather stations across the valley. They also went door-to-door asking growers for phenological data—sometimes sifting through attics of old notebooks to find out when farmers planted and harvested over past decades, and what they jotted down about the weather and the grapes.

The end result was over 12,000 data points that told a different climate story: that temperatures have increased over the last 70 years or so, but only by about 0.5 to 1.1 degrees Celsius (1 to 2 degrees Fahrenheit) in Napa Valley. The study is not an attempt to undercut climate science, but rather make it fine scale enough for wine growers to use.

“I am so not a climate denialist,” said Graves, a member of the task force who in fact has an app on his phone that offers research-grounded rebuttals to common climate denial arguments. “It’s actually ironic that I am here in an area that’s not experiencing warming.”

The past, however, is not a blueprint for the future, and the NVV realizes that climate change will likely reach their valley oasis. But how much temperatures will warm and exactly how precipitation patterns may change is unclear. “They’re all curveballs,” said Stults.

Big data, or back to dirt?

Napa Valley Vintners is quick to point out that vintners are farmers that have been adapting their business in the Napa Valley for two centuries. “For the farmer, change is not only inevitable; it is a way of life,” their press release on climate change states.

The more interesting question, then, is not if vintners will adapt, but how. A few practices that have been used for years may come into play if Napa Valley begins to see more temperature extremes. Because Napa is warmer than many grape-growing climates in France, Napa growers use trellising strategies to raise the grapes higher off the ground and leafing strategies to shade them, therefore manipulating the microclimates around the vines. They can maneuver plants around aspect, or the cardinal direction that hillsides face, essentially turning a vineyard in a different direction to alter the sunlight it receives.

Some vintners are trying out higher-tech options, like using solar-powered sensors on every vine to monitor plant hydration and make their water use more precise. Graves of Saintsbury told us he’s interested in trying out a new product called Surround that can be sprayed onto fruit to increase its albedo, or reflectivity, effectively cooling the plant (it’s already being used for apples). But vintners have different ideas about the role of technology in building their resilience to climate change.

“The potential to do the big-data version of farming: we’re just at the beginning of that. The question is what do you do with big data?” Graves said.

Chris Howell, who runs the 90-acre Cain Vineyard & Winery where he grows six varieties of grapes, installed a weather station on the vineyard in 1995 but doesn’t see ‘big data’ as a savior. “I don’t really believe that technology will help us. It’s more important to focus on the basics: dirt, weather (that’s the vintage), climate, and winemaking, which is just the simplest kind of cooking,” he said.

Graves agrees that there are some low-tech ‘adaptation options’—such as diversification—that haven’t genuinely been tried yet. “The world’s wine grape crop is dominated by 10 cultivars. And that’s just dumb. There are probably some pretty interesting cultivars that already exist that are optimized for a warmer temperature regime,” he said.

“Cabernet is the dominant variety in Napa. Will it be in 50 years?” Howell asked—rhetorically, of course. Even those who live and breathe for wine don’t know the answer.

Despite what the doomsday news articles say, though, vintners definitely don’t plan on moving on from the Napa Valley anytime soon. “The odds of Napa Valley not being in the wine grape business by 2100 due to climate change are small. But what the grape and wine business looks like in 2100, I have no idea,” said Graves. 

The curse of incremental change

The NVV study’s finding that the warming signal has—so far—been weak in the Napa Valley is both a blessing (grapes aren’t getting scorched) and a curse (well…what now?). Growers plant on a 25-year cycle, meaning that the decision to plant a new variety or not only comes up four times every century. This leaves vintners in a catch-22: the climate models are too broad-stroke (often global in scale) for them to make decisions about the future, and yet the Napa-scale study only captures the past. Graves told us that, had there been a clearer trend line in the local data, his decision-making would be a lot easier.

What would Graves do if there were a steeper temperature trend? “I would be doing a lot more homework before I picked the next cultivar. It might be something alphabet soup. Maybe a Croatian variety,” he said.

Howell said that close observation will be key to future decision-making. “[We can’t] take our eyes off the ball,” he said. “We need to keep talking. The sooner we see a pattern, the sooner we can react.”

Vive les ‘vineyards’

The good news is that talking (to each other) is something vintners do well. Disseminating information and ideas is the entire premise of the NVV. “That’s one of our biggest advantages, not just for this issue [climate change], but all issues,” said McGaughy.

When we asked Graves what makes Napa Valley vintners resilient, he didn’t mention growing strategies or access to technology, but rather “intellectual capital” and “empirical experience on the ground.”

And for vintners, dealing with imperfect knowledge about climate is not only nothing new—it’s what keeps them in the wine game.

“I really enjoy the intellectual challenge of trying to sort all this stuff out,” Graves said, in response to our question about what he liked most about being a vintner. “The number of variables is daunting, but on the other hand it’s never boring. Plus, I can bring my dog to work.”