Wine World

How climate change is affecting Sonoma and Napa vineyards

Excessive sunlight could impact vineyards. Photo: Feverpitched

While there are some who reject mainstream climate science, the reality of climate change could possibly hit us right where it hurts: our Northern California wine industry. Viticulture, the cultivating and harvesting of grapes for winemaking, can be found on every continent except Antarctica, with the vast majority of the world’s winemaking regions existing between the temperate latitudes where the annual mean temperatures are between 50 and 68 degrees. Sonoma and Napa counties are in this sweet spot, and produce some of the finest fruit and wine in the world.


According to a 2014 joint publication by the U.S. National Academy of Sciences and the Royal Society of the United Kingdom, the global average surface temperature has increased approximately 1.4 degrees Fahrenheit since 1900. Despite climate change uncertainties, the gradual temperature rise is projected to continue in the future and is anticipated to affect viticulture worldwide. This means winegrowers will have to adapt to climate change using various mitigation strategies, such as growing grapes in cooler climates, changing how grapes are grown, harvesting earlier, and other strategies.

Wine composition — the taste, the aroma, the mouth feel — largely depends on microclimates. For high-quality wines to be produced, the balance of climate, soil, and grape variety has to be maintained. However, the interaction between climate-soil-grape may, in some cases, come under threat from the effects of climate change.


How is climate change impacting our mainstay market here in our Wine Country? I put this question to these vineyard managers and winemakers: David Parr, Dos Abuelos Wines; David Pirio, Chappellet Winery; Greg Stach, Landmark Vineyards; Phillip Titus, Titus Vineyards; and Bill Williamson, Williamson Wines. Here is what I learned:

While temperature, rainfall, and drought are deciding factors each year, the variations we are experiencing from a grape-growing perspective are well within the normal variances experienced over the past half century, according to Pirio. Short term, climate change impact is minimal at best, and as Williamson said, climate change will not significantly disrupt the industry until our “grandchildren have grandchildren.”

Long-term changes are important; however, and researchers are experimenting with various mitigation efforts, such as canopy protection to prevent vines from being burned by excessively hot sunlight, which reduces their yield. Other long-term strategies include rootstock grafting to create resilient vines and biodynamic farming practices.


If you have visited the Wine Country recently and been curious about the looming piles of grapevines in excavated vineyards, it is due to climate but not climate change.

Growers are replacing vineyards to accommodate the terroir (a combination of factors including soil, climate, and topography) to maximize the ability to produce high-quality grapes of specific varieties. Replanting rows to take advantage of sun direction and eliminating vines that are infected with common viruses, like red blotch and leaf roll, are essential to increasing yield and grape quality. What is most critical is managing the yield and making year-by-year winemaking decisions to maintain quality to meet market demands. This combination of skills is what has, and what always will, make great wine.


All the wine experts agreed that climate change is too slow for immediate concern. The last two years of wildfires, which had devastating economic effects from loss of vineyards to smoke taint of grapes and other damage, may be nothing more than normal annual seasonal variations. For example, 1972 and 2008 were years of heavy frost and cold damage. These years were followed by wet weather, and the wet years produced what Pirio called “too much vigor in the vines” — extra growth, more shoots, and larger berries as opposed to the more desirable and intensely flavorful smaller berries.

Our experts agree that climate change is real. However, it does not appear to be an imminent threat to our Sonoma/Napa winemaking industry. It is heartening that all were concerned about the negative effects of climate change and global warming on humans.

The vines will survive. They are tough, they are rugged, and they are resilient. It seems our future wine industry is also resilient and, when properly managed, will survive and flourish.

Kenneth Majer is a consultant to the wine industry. E-mail: [email protected]

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