The Endangered Heart of Wine County

Climate change in Napa Valley

by Dana Cronin


I grew up in one of the top wine meccas of the world: Napa Valley, Calif. Wine Country. It’s a place where the majority of people you see walking down Main Street are tourists, slowing traffic to admire the vineyards and wineries along the highway. It’s a place where high school students have the option of enrolling in a viticulture class, where it’s weird for the parents of a friend not to be involved in the wine industry, and where I’ve dealt with numerous inebriated customers at work, drunk from wine tasting all day.

My dad’s name is David Cronin. He attended Colorado College in the late ’70s and graduated with a degree in Geology. He moved to St. Helena, the heart of Napa Valley, when he was 25 to be a part of the industry. Since then, he’s started his own small wine label and become the sole winemaker for Buehler Vineyards. 

When I was young and got sick, my dad would take me to work with him. For most young girls, this means spending all day doing anything she can to stay entertained while her dad sits at his desk, staring at his computer screen from 9 to 5. 

When my dad took me to work, we would drive into the Napa Valley hills, winding through vineyards, passing ranches and horse stables, catching glimpses of lakes and reservoirs. When we arrived at the winery, we would be overcome with the sweet smell of grapes. We would enter a room full of winemaking machinery that looked massive from my 9-year-old perspective. I got to climb around the tanks while my dad did whatever it was he came there to do. It was a blast. On our way out, he would always give me a cup of unfermented “sweet wine,” which was essentially grape juice. In my mind, it was the best-tasting liquid on the planet. 

Now, I’m 20 years old and my perspective is changing. I’m studying Environmental Science here at CC and learning a lot about climate change: an abstract concept with abstract implications. In all honesty, it will probably remain vague for most of us until it changes something in our day-to-day lives. For my dad and me, that day might not be so far off.

With an established life in St. Helena and in the wine industry, it’s hard to think about change. But according to the overall trajectory of climate change, in centuries to come the Napa Valley wine industry may be very different from what it is today. Even for me, having grown up around the winemaking process, it’s hard to understand the detailed science behind climate change and its effects on the industry. So, I asked my dad. 

Wine is made from grapes, so a decrease in the quality of grapes means a decrease in the quality of wine. The quality of grapes is determined by three main factors: climate, soil and topography. 

Different varieties of grapes produce different types of wine. For example, there are Chardonnay, Pinot Noir and Cabernet Sauvignon grapes. Each variety thrives in different climates: Chardonnay and Pinot Noir require a cooler climate like that of Sonoma, Calif. or Burgundy, France, while Cabernet Sauvignon requires a warmer climate like that found in Napa Valley or Bordeaux, France.     The price of a bottle of wine is dependent on the variety of its grapes. Cabernet Sauvignon is the most expensive grape variety in the country and, according to the Napa Valley Vintners’ website, it accounts for 40 percent of Napa Valley’s total crop production and 55 percent of its crop value. 

In the next 100 years, Napa Valley will likely experience a temperature increase. It may become too warm to grow high quality Cabernet grapes any longer, forcing the industry to adapt to grape varieties that are more temperature-resilient. Although this adaptation is possible, the economic loss would be huge. Even if it were possible to replace all 40 percent of Napa’s total crop production with a variety other than Cabernet, there would be a net income loss since Cabernet grapes are the most expensive in the country. 

For example, the grapes of Napa Valley are about eight times more expensive than the grapes of southern San Joaquin Valley (located in the hotter Central Valley region of California). What would happen to grape prices if Napa Valley’s climate more closely resembled the southern San Joaquin Valley?

According to my dad, “Granted, there are soil and topography differences between the two growing regions, but the likely impact of warmer climate on grape quality and grape prices can’t be ignored and could be huge for the local economy.”

Temperature fluctuations are only part of the story of climate change. Annual rainfall amounts are as important as temperature. Climate change projections predict changes in annual rainfall all over the world. 

There is little to no rainfall in Napa Valley in the spring and summer. Rainfall encourages the growth of many undesirable molds and mildews, making the grapes rot. Mid-latitude regions are generally the most desirable for grape growing with annual rainfall at around 35-50 inches. If the timing of this rainfall changed, the region may no longer be considered suitable for wine growing. If rainfall amounts were to dwindle to the point of aridity, theincreased soil salinity would hurt the health of the vines. 

Clearly, industry adaptation will be necessary in the coming era and must come in many forms. Harvesting grapes at night, for example, may be necessary to deliver cool grapes to the winery. Since acid is respired at a higher rate in warmer climates, more acid may be added to crushed grapes. Sugar levels may need to be monitored more closely, as they climb faster and spike more frequently in warmer climates. 

My dad also wonders about the possibility of using genetic engineering to create more resilient grape varieties. “When large sums of money are at stake, as they will be, humans come up with creative solutions.”  

No one is certain what the fate of Napa Valley (or any other wine-growing region) will be. There are best and worst case scenarios, but in reality, who knows what will happen? Maybe there will be missing wineries along the highway I drive almost every day. Maybe families like mine won’t even exist in the region in fifty years. 

The facts provide me with a glaring image of climate change. It gives me a perspective that textbooks, movies and news articles cannot. 

My dad shares this perspective with additional concern: “I think of the vintners who have worked so hard to make Napa Valley what it is today. I think of their descendants several generations down the line and wonder if they’ll migrate north, abandoning their Napa heritage in order to maintain their winegrowing heritage. What will be left behind?”

Will a 9-year-old girl still be able to venture to her father’s winery when she stays home sick from school? 

I hope she gets to see the rolling Napa Valley hills covered with vineyards rather than barren landscapes; I hope she can climb on all of the gigantic winemaking equipment and taste the flavor of sweet wine. I hope she has the opportunity to walk through the vineyards filled with dangling, plump grape bundles. I hope she loves growing up there as much as I did. And when she grows up, I hope she doesn’t have to worry about losing her home.