Over the next 30 years, premium wine production in Santa Barbara County could drop as much as 20 percent, a consequence of rising temperatures associated with climate change, according to a recently released Stanford University study.
Using computer models and assuming a nearly two degree jump in average global temperatures by 2040, scientists predicted the county would likely experience higher average temperatures and 10 more “very hot days” above 95 degrees Fahrenheit during growing seasons, thereby reducing the amount of acreage for producing fine wine grapes locally.
“We see losses in suitable area for the more restrictive temperature tolerances and the potential for those losses to be reduced if more heat can be tolerated,” said Noah Diffenbaugh, the study’s co-author and a fellow at the Woods Institute for the Environment at Stanford. “We’re certainly not ringing the death knell or trying to sound any alarms. It’s simply an objective, quantitative scientific study, and it’s really focused on what the possible environments are going forward over the next three decades.”
Diffenbaugh said the impact of temperature change found in the study was more immediate than he expected, and said the projected decline in wine grape production could be offset if growers adapted to warmer weather conditions by planting more heat-tolerant vines, altering cultivation to increase shading, implementing irrigation to cool plants, and adjusting orientation of grapevine rows.
The study’s authors noted acreage in the county could actually be increased if growers were to change varietals to those fit for warmer temperatures: up to 45 days above 95 degrees and average temperatures of 71 degrees during the growing season. However, researchers said, varietals grown in such conditions produce wine of lower quality and value.
“Once the temperature gets into the hot end of suitability, the physiology of the grapes is such that the balance is affected,” Diffenbaugh said. “There’s not a lot of empirical evidence of really high quality, high value wine being produced from grapes that are grown in really hot conditions.”
The Stanford study, released in the June 30 edition of Environmental Research Letters, focused on how global warming could affect premium winemaking conditions in Santa Barbara and Napa counties in California, Yamhill County in Oregon’s Willamette Valley and Walla Walla County in Washington’s Columbia Valley.
According to the Wine Institute, Santa Barbara County’s 90 wineries currently generate about $400 million in revenue, with Chardonnay and Pinot Noir being the most prominent varietals.
The question of whether or not the study’s findings will actually alter the decisions growers make in their own vineyards, Diffenbaugh said, is likely to be answered by individual growers and how they read the environmental conditions on the ground.
“There’s a lot more than temperature that goes into growing grapes or making wine,” he said. “What will happen over the next three decades remains to be seen, but we certainly do see potentially important temperature changes emerging when we apply the most detailed climate models to this problem.”
This article appears in Jul 14-21, 2011.
