Wine Decline In Napa

Temperature shifts have varying effects based on region, but typically result in:

• decreased grape quality due to advanced harvest dates;

• higher sugar content;

• lower acidity;

• reduced shoot and berry size;

• more tannins;

(Ashenfelter and Storchmann, 2016; Bai et al., 2022; IPCC, 2022).

Therefore, climate change is poised to drastically decrease total output of high-quality wine, and the overall quality of that wine, particularly in key areas such as Italy, France, Argentina, China, and the focus of this case study: Napa County, California (Shultz and Jones, 2010; Mosedale et al., 2016; IPCC, 2022). 

Key impacts of Climate Change will involve:

• Increased drought changing harvest dates and reducing shoot growth and berry size (Cook and Wolkovich, 2016; IPCC, 2022);
• Spread of insect pests, increasing in number, generations per year, winter survival, survivable area, more invasive species, and more plant diseases (Skendžić et al., 2021; Gutierrez and Ponti, 2022);
• Increased wildfire occurrence, resulting in burning of crops and tasting rooms as well as smoke taint and worsened destination image (Bauman, Yuan and Williams, 2019; Kropp and De Andrade, 2022);
• And as a product of each of the previous issues, massive economic losses in California’s wine industry, particularly in the Napa region (Ashenfelter and Storchmann, 2016; Fourth National Climate Assessment (FNCA), 2018; Bauman, Yuan and Williams, 2019; Downey Brand, LLP, 2021; Gbejewoh, 2021; Yasui et al., 2021; IPCC 2022).

One key hazard for grape growing is change in drought conditions. Seasonal drought was originally a key factor in successful grape growing, but only when it consistently occurred in the later parts of summers and followed a wet season. This allowed vines to have time to mature and then for them to be forced into focusing on grape growth due to decreased moisture availability (Cook and Wolkovich, 2016). Now, these late season droughts are irrelevant to grape growers as droughts begin much earlier and force vines into fruit production with much smaller buds, which results in fewer and less mature grapes (IPCC, 2022). Net water requirements of agriculture are also projected to increase over the next century, putting even more stress on the region (Funes et al., 2020).

Wildfires in the Napa Valley area, the primary area of wine production in California, have already begun to damage crops and community alike. Community-wise, studies have found wine tourism, one of the largest economic contributors to the area, has taken big hits- wildfires have caused extensive concern for the industry, including fear of the fires as well as worry about the industry (Bauman, Yuan and Williams, 2019). The destination image has worsened significantly, which has huge negative economic implications (Lai and Li, 2016). Crops and tasting rooms are burnt down directly at times, but more impactful is the indirect effect of smoke exposure (Kropp and De Andrade, 2022). This typically leads to smoke taint, a burnt aftertaste in wine, which often affects much more widespread areas than are affected by direct fires. When mild, smoke taint makes wine quality worse. When extreme, it makes grapes not harvestable or wine unsellable. In 2020, this resulted in $601 million of Californian wine grapes going unharvested (Downey Brand, LLP, 2021), and another $227 million being paid in crop insurance (Yasui et al., 2021).

California wine seemingly benefits from climate change in many ways currently. Frost decrease in both days of the year it is present and of land on which it appears has resulted in similar or increased yields for wine grapes. However, this benefit will not last if climate change continues, but rather will be reversed (Gbejewoh, 2021). These projections of increased production have already been found to be inconsistent or untrue in other crops. Almonds, the second most produced specialty crop in CA behind grapes (Kerr et al., 2018), had been projected to increase in their production by and after 2018, but because of the droughts offsetting the more favorable growing temperatures, production has instead greatly decreased (Reisman, 2019). 

Timothy Boyce, originally from Silver Spring, Maryland, graduated from St. Lawrence University in 2025 with a Bachelors Degree in Environmental Studies. He competed in cross country and track and field for the university, and continues to pursue athletic goals post-collegiately. He worked on his parents vineyard in Mount Airy, MD throughout his childhood. He is very interested in computer science and in social justice movements in his free time.