It's a standing joke, though a somewhat nervous one, among winegrowers when the subject of global climate change comes up. "Well, I guess they'll be growing Cabernet in Burgundy," someone is sure to remark, "because it will be too hot to grow Pinot Noir there anymore."
But how true is that idea? Is it likely that whole regions will get too hot for what they currently grow? That would change the dynamics of wine profoundly. Noah Diffenbaugh, a fellow at the Woods Institute for the Environment at Stanford University, enlisted colleagues at Utah State and Southern Oregon universities and the Oak Ridge National Laboratory to plug in conservative climate models and analyze what would happen region by region in California, Oregon and Washington if those models come true.
Diffenbaugh is the guy who scared the pants off of everyone when he predicted in a 2006 climate study that 81 percent of U.S. premium wine acreage could become unsuitable for their current varieties by the end of the 21st century. This new study narrows the focus to wines in the top 25 percent in value and limits the time frame to 30 years. The authors point out that vintners actually consider the costs and benefits of making decisions about their vineyards in this time frame.
An increase of 1.8° F in average daily temperatures over the next 30 years, about what the conservative estimates expect on average, could affect a significant percentage of current vineyards, enough to require replanting with different varieties if they want to keep growing high-quality grapes. On the other hand, adaptations could also come into play to soften the effects. New clones, vine-training systems and smart water use could make the vines and the grapes more tolerant of higher temperatures, and still produce high-quality wines.
One big issue may be the number of extra-hot days in a growing season. That would vary from region to region, the computer models say, and could be more significant than average temperatures if a vine has to withstand 50 extra-hot days per season instead of 20. In some of the models, that could happen.
Bottom line, according to the study, in some regions as much as 50 percent of the vineyard land now suitable for high-quality wine could no longer be that good, if no changes are made. At biggest risk, they note, are regions that are now considered warm, such as Napa Valley. Cooler regions, such as Santa Barbara, Willamette Valley and Columbia Valley, could see only 20 percent of current vineyards get too warm to make high-quality wine with their current grape mix.
So maybe we won't see Pinot Noir being replaced by Cabernet. But Cabernet for something else? Um, Syrah? Grenache? That could be a game changer.
On the bright side, some land currently considered unsuitable because it's too cold could get warm enough to become prime vineyard acreage. Higher elevations, the study suggests, could become more and more important.
This is not limited to the West Coast of the United States, either. Every wine region in the world will have to find ways to cope with a gradually changing climate. It's a complicated story, and it's a good thing someone is trying to figure out exactly what could happen.
Here is the full text of Climate Adaptation Wedges: A case study of premium wine in the western United States.
Follow Harvey Steiman on twitter at twitter.com/harveywine.