It’s a fact that increasing temperatures will impact wine-grape growing. I’m not arguing one side or the other of the climate change debate. You either believe humans are the cause of increasing temperatures or you think this is a normal cycle of warming. The whole debate has become another way to fracture people into different camps. Personally, I’d like to go out into the wilderness alone, away from any camp, and sit under the stars. However, given that I’d have to come back at some point, my hope is that we continue our trend toward building cleaner technologies that are more efficient, effective and sustainable than what we’ve done in the past.
Whatever the cause, temperatures have been increasing over the last 100-plus years. Because wine grapes are affected by temperature, it follows that a changing environment will affect grapes, too.
One way to deal with the impact of rising temperatures on grapes is to plant varieties that do better in warmer regions. Farmers have been doing this for years, experimenting and finding what works when and where. For example, in the past there have been those who tried to plant Riesling in the Napa Valley, but they found the Bordeaux varietals seemed to better fit the environmental profile. Experimenting in California is one thing, but if you’re in a region that has become so aligned with a particular grape, experimenting is a touchy subject. In Europe, there are often rules as to what and where farmers can plant in many regions. Try planting Cabernet Sauvignon in Burgundy and you’ll not only be breaking the rules but you’ll probably be ostracized from your town and even the country, perhaps run out by a crowd of angry villagers.
Researchers are exploring the effects of higher temperature on wine quality and finding that warmer conditions often seem to reduce the number of berries per vine and hamper carbon assimilation, which can have a direct influence on quality. Higher temperatures also increase the amount of sugar concentration in the berries but hinder malic acid and secondary metabolite formation, which can lead to unbalanced wines. To deal with this, some scientists are attempting to create genetically modified grapevines that can thrive in hotter climates, such as hybrids between two species of a wine grape, V. labrusca and V. vinifera that appear less affected by changing temperatures. As a reminder, V. vinifera is the European species of grapes that is the most common source of the wines we drink today. The other, V. labrusca, is native to eastern North America and is the source of many of our cultivated table grapes, such as the common Concord grape that is also used to make jams and jellies. Hybrids of V. labrusca and V. vinifera are not new and have created such varieties as Agawam, Alexander and Onaka, which produce obscure but distinctive wines, many of which have a musty or “foxy” aroma.
Scientists and farmers have historically looked to improve stocks and deal with changing conditions by creating new forms (breeds, hybrids or other genetically modified organisms). This approach often works, but it’s not without risk. A hybrid that wreaked havoc in Northern California was the AXR1 rootstock that was widely planted during the 1960s and ’70s to thwart the dreaded root louse (aphid), Phylloxera. AXR1 is a cross between Aramon Noir, (itself a V. vinifera cultivar) and another American grape species, V. rupestris, which was also used as “St. George” rootstock, referring to a town in the South of France, Saint-Georges-d’Orques, where it became popular.
By the 1980s, the ever-persistent Phylloxera had found a way around the hybrid and started to kill off thousands of acres of vineyard land, resulting in the economic collapse of many small farmers. My wife’s family vineyard was one small example. Unable to afford to replant, her parents were forced to sell their land.
Manipulating the natural world to address a changing environment is what humans have always done. However, there are times when we might want to take an easier path and find a more natural response, such as planting grapes that do well in the environmental conditions of the time and place, recognizing that these conditions will change. The increasing temperatures will provide plenty of opportunities to experiment. My hope is that at least some of these experiments include simple approaches such as changing viticultural practices or planting more appropriate varietals, even if this sometimes means facing the torches and pitchforks.
Cows grazing along hillsides and in seaside meadows are a picturesque and familiar sight in Marin and Sonoma counties. Dairy farms have been a local presence for more than 100 years, but thes...