Napa climate change: Tempest in teapot

Vintners report it's too early to foretell winegrowing future

Napa, Calif.—Napa Valley Vintners assigned a group to analyze trends in climate change and how it could affect the valley’s wine industry. The recently reported results: Unknowns still outweigh certainties.
 
“We’re still not interested in denying climate change is happening,” said Chris Howell of 23,000-case Cain Vineyard & Winery, a member part of the vintners’ committee on climate change. But, he added, it’s not happening to the extent feared, and widely reported.

A few years ago, it seemed that the end had been foretold for Napa Valley’s multi-million-dollar wine industry. Vineyard owners were advised they might as well pull up those vines and move north to cooler weather; in a few decades, climate change would make Napa too hot to support the high-quality grapes that had made its reputation.

“We were the canary in the coal mine for climate change,” Howell said of that time in 2006, when Napa’s pending doom from climate change was first reported. “It took Napa Valley to pique people’s interest in climate change.”

The story took off with an article published in USA Today and followed up by other news outlets. In June of that year, a Stanford University study concluded Napa could lose up to 50% of its vineyards to climate change.

Howell and Rex Stults, industry relations director for Napa Valley Vintners, recently reported to other growers and winemakers about the vintners group’s efforts to study climate change at a seminar about water conservation.

What’s new?
Stults said a frequent joke at climate change conferences is “What’s new?” The answer: Almost nothing. Climate change takes generations to occur or perceive.

While the number of growing-degree days has in fact risen, what this could mean for the valley is uncertain. He added that while there has been research into the valley itself, how it is impacted by the wider regional climate area is anyone’s guess. “We've got one of the more difficult locations to predict,” Stults said.

If the weather does become progressively hotter, Brix levels and alcohol in wine could continue to increase; at a certain point, the vines can no longer keep up with the heat and could fail to achieve optimal ripeness.

The most immediate effect on vineyard operations might involve changes in trellising to compensate for warmer days or nights. “The first thing would be to adapt trellising schemes,” Stults said.

In discussing climate change, he added, it’s important to avoid fixating only on temperatures. Changes in high and low degree points are important, but Stults said it’s key not to lose focus on the bigger picture: How that could affect larger systems such as the marine influence on the valley and overall rainfall patterns. “We’d love to have more info on that,” he said.

Napa Valley Vintners commissioned its own report after the spate of news coverage about climate change affecting the valley’s wine industry. The vintners’ subcommittee developed its own research plan to find more data on average temperatures in the valley. Howell said the group enlisted the help of Daniel Cayan, a researcher with the Scripps Institution of Oceanography who specializes in climate variations and the affects of climate change on California and western North America.

Research foretelling dramatic climate change for the valley was based on data from two collection points—one at the southern end of the valley at the Napa State Hospital and another at the northern end in St. Helena, according to Howell.

Neither station could comprehensively document the vast array of climate and temperature differences that span the diverse topography of the Napa Valley on any given day, Howell said.

The four-year project involved 12,000 data-collection points; some came from digging through barns to unearth the old journals of farmers who kept track of the valley’s highs and lows. “A lot of people have a lot of information. We said, ‘let’s go out and harvest this information,’” he said.

Ultimately, the study released in February found that temperature change in the valley had been limited to just a slight warming of 1ºF to 2ºF in nighttime lows.