Rhone varieties should be (even more) valuable in a California impacted by climate change

Over the last month, I've had three different wine people ask me some version of the same question, asking me to share what I thought were the right grapes to be planting in California right now, given the near-certainty that they'll mature in a future notably warmer (and probably drier) than today. That question is usually followed by another asking whether we're looking outside of the Rhone family for future plantings, or if we think we've already got the right collection of grapes to allow us to succeed. So, in the spirit of using this blog to answer the questions I get every day, let's dive in.

Casual wine drinkers may not realize the full extent of the diversity within the vitis family. There are 79 accepted species of grapes, of which the species that encompasses all non-hybridized wine grapes (vitis vinifera) is just one. Within vitis vinifera more than 5,000 different varieties have been identified. Of course, not all are used to make wine commercially, but in the authoritative tome Wine Grapes, Jancis Robinson and her co-authors identify 1,368 different grapes worth documenting for their use in wine around the world. That's a mind-boggling number. What's more, at least half of these have proven useful and adaptable enough to have been brought to regions outside where they first evolved. In California alone, Foundation Plant Services at UC Davis has 479 different non-rootstock varieties in their collection for nurseries, growers, and wineries to purchase. 

Yet if you ask most American wine drinkers to name grape varieties they'll probably struggle to rattle off even a dozen or so. The best known grapes come from high-profile regions in France and Italy. A quick look at the best-selling varietal wines in the United States from 2020 begins with Cabernet Sauvignon and end with Malbec, with the "big" grapes Chardonnay, Pinot Gris/Grigio, Sauvignon Blanc, Muscat/Moscato, Merlot, and Pinot Noir making up the rest of the top tier. There's a huge dropoff after the first few grapes, and a twelve-fold difference between #1 Cabernet and #8 Malbec. 

What do you notice about those eight grape varieties? One thing that jumps out to me is that they all are best known from regions that we think of, at least in the word of wine, as being either cool (like Burgundy or the Loire) or mid-warmth (like Bordeaux or northern Italy). This is all the more surprising given that all these modern-day regions are cooler than where modern research suggests vitis vinifera was first domesticated in the hot, dry climate of the eastern Mediterranean, somewhere near where modern-day Turkey, Armenia, and Iran meet.

All this is a long way to say that not only is much of California wine made from just a few grapes, but also that those grapes are representative of a narrow, continental European part of the much wider spectrum of grapes used to make wine.

How does California's climate relate to that of, say, France? It's complicated, both because California is big and how hot it is here is determined at least as much by our distance from the ocean as it is by how far north or south we are in the state. But it's still possible to make some general observations. California wine country is quite a lot further south than nearly all of Europe. San Francisco is roughly the same latitude as Seville, in Spain's hot, dry south. There's no part of California that's the same latitude as Burgundy (but Quebec City is). Paso Robles is the same latitude as places in the southern Mediterranean like Tangier and Cyprus and Tripoli. Of course, climate is not determined solely by latitude; California is cooled by the chilly Pacific Ocean, while Europe is warmed by the Gulf Stream. And both regions are subject to the impacts of a warming climate. But when I went to look for the best climate comps to Paso Robles in a blog about our climate from 2017, the closest match wasn't Bordeaux, or Burgundy, or even Chateauneuf-du-Pape. It was the Bekaa Valley, in Lebanon.

My point in diving into all this is that if we were looking just for grapes that would do well in the intense sun and summer heat of a place like Paso Robles, we wouldn't start our search in a region like Bordeaux or the Loire. It would be someplace sunnier and drier, and likely farther south. So how were the grapes that are found here chosen? They were what was in demand in the global wine market (or perhaps they were the grapes the people looking to get into grapegrowing and winemaking were familiar with, which is related). You'll see that the mix in Paso Robles, like much of California, is dominated by Cabernet Sauvignon (image from the Paso Robles Wine Country Alliance press kit):

It's important to remember that the mix of grapes here wasn't the result of extensive experimentation about what would be best suited for the California climate. So if we were to make the case that Rhone grape varieties might be the right grapes for a California whose climate is already more like that of the Eastern Mediterranean than Continental Europe, and continuing to warm, how would we go about it? We might start with evolution. In just about every case, Rhone grape varieties evolved in hotter climates than grapes like Cabernet, Merlot, Sauvignon Blanc, and Pinot Noir. Some, like Grenache Noir, Grenache Blanc, and Mourvedre, evolved in Spain. Chateauneuf du Pape is at the northern extent of their viable range. Many others appear to have evolved in the southern Rhone or nearby Languedoc, including Counoise, Cinsaut, Vaccarese, Muscardin, Picpoul, Picardan, Clairette, and Bourboulenc. That leaves four that research suggests evolved in the northern Rhone: Syrah, Viognier, Marsanne, and Roussanne. You can make the case that the northern Rhone is a similar climate zone to that of Bordeaux or northern Italy. But Aragon, the Spanish homeland of Grenache (known there as Garnacha), and the Levante, the Spanish homeland of Mourvedre, are both significantly warmer and sunnier, as are the areas around and west of Avignon where the bulk of the Rhone grape pantheon evolved.

Looking at points of origin isn't conclusive evidence. But it's suggestive. Typically a plant is adapted to thrive in the place in which it evolves. That gives us a good clue to where we might look for grapes suited to a warming future California. Another clue is the research that has been done here, particularly in the era before California's wine regions were defined like they are today. Here we're helped by a remarkable 1884 Ampelography of California (cover page featured right) written by Charles Wetmore, the state's first Chief Executive Viticultural Officer. In it, he explicitly tackles the question of the "adaptability to certain locations and uses" of the grapes known at that time in California. Were his conclusions to plant lots of Cabernet Sauvignon and Chardonnay? Nope. He saved for his particular praise Zinfandel and Mataro (Mourvedre) of which he said, "the Zinfandel and Mataro, each good bearers, will each become the favorite basis of our red wine vineyards." I wrote back in 2020 about his enthusiasm for Mataro, of which he says "Although this is not as extensively cultivated now as other varieties for red wine, yet its present popularity demands for it a place next to the Zinfandel; indeed, I believe that for the future it will have a wider range of usefulness."

For cooler regions he recommends Trousseau for its "general adaptability and fine qualities." For drier regions he suggests Grenache, which he says "will succeed and flourish in arid places, where Zinfandel would fail." And he expresses interest in future experiments on grapes like Cabernet Sauvignon ("I believe that those who aim at fine wines of a Bordeaux type cannot afford to be without it") and Spanish whites like Verdelho and Palomino ("Our best success may be in those types"). Zinfandel evolved in the warm southern coast of Croatia and thrived in the heel of Italy as Primitivo before coming to California presumably with southern Italian immigrants. Chalk another mark up for looking to warmer parts of Europe for California's vineyards.

Finally, let's look at what we're seeing in our own vineyards. In another blog from 2020, I talked about how the warming climate is making the higher-acid Rhone whites like Picpoul, Picardan, Bourboulenc, and Clairette Blanche more valuable both here and in the Rhone. I would submit that the same things is true for reds like Counoise, Cinsaut, Vaccarese, Terret Noir, and Muscardin. At last night's En Primeur Live broadcast, Chelsea and I were talking about the impact of the newer varieties on the 2021 Esprit de Tablas, which has our entire production of Vaccarese (7%) and Cinsaut (5%) as well as 4% Counoise. My analogy was that adding these grapes, all of which have good acid and in the case of Vaccarese also dark color and tannic grip, was like turning up the contrast on an image, or turning up the bass and treble on a piece of music. They make the wine more dramatic, even as its core character is determined by the mid-palate richness and balance of earth and fruit that Grenache, Mourvedre and Syrah provide. We haven't yet found a home in the Mourvedre-based Esprit de Tablas for the even higher-toned, grippier Terret Noir and Muscardin grapes, but they're doing wonderful things to the Syrah that provides the base for our Le Complice bottling.

This is not purely an academic question. There are practical considerations. A widely-shared 2019 article in Wine Business Monthly made the case that within thirty years "many current Napa vineyard locations will be too warm for some Bordeaux varieties to scale luxury-priced wines" and "anyone planting or replanting a vineyard today should be taking climate warming trends and optimum grape-growing temperatures into account." A 2019 study suggested that if global temperatures rose 2°C, grapegrowers in Burgundy and Bordeaux could cut their climate-related losses in half by planting with Mourvedre instead of their current grapes. Just last year, France's Institut National de l'Origine et de la Qualite (INAO) approved the use in Bordeaux six new varieties "of interest for adapting to climate change". Closer to home, we're getting more requests through our grapevine nursery for the high-acid grapes in our portfolio -- like the Picardan, below, that we ourselves only first planted in 2013 -- than I can ever remember.

What the right grapes will be for this warmer, drier California isn't clear yet. But if the rest of the world is looking to the grapes of the Rhone to help mitigate their own climate change concerns, it seems likely that we'll be able to shift within that Rhone family to make sure that even as things get warmer and drier, we'll be able to make great wine. I have faith in the diversity of vitis. And in the blending tradition of Chateauneuf du Pape.