Larkmead Vineyards in Calistoga, California, embodies the Napa Valley of popular imagination. At the beginning of harvest, vines heavy with inky clumps of grapes stretch out in perfect rows, their leaves showing the faintest yellow tinge of autumn’s impending turn. The grapevines run for 110 acres to the base of the Mayacamas and Vaca Mountains, interrupted only by the occasional service road and a quaint white farmhouse.
But picturesque landscapes are not what Dan Petroski, Larkmead’s winemaker, wants to show me when I arrive at the 124-year-old vineyard at the end of August. Instead, he trots me over to an empty field. “This is our future,” Petroski declares, spreading his arms proudly in the direction of the ruddy expanse of gravely, clay-based soil. “This is three acres we are committing to the next 21 years to figure out what’s going to be the next great wine grape of Larkmead—and hopefully of Napa Valley.”
Right now, the distinction belongs to the cabernet sauvignon grape, which accounts for more than 80 percent of Larkmead’s annual harvest and produces the type of cabernet wines that have defined Napa for decades. A wine made with Napa cabernet sauvignon grapes, picked at the height of ripeness, will be intensely flavored with ripe plum, black currant, and floral notes. But as the valley sees warmer nights, less fog, and more days that surpass 100 degrees, Petroski and his fellow Cabernet producers are struggling to ripen their grapes as they lose the conditions that once gave their wines a flavorful edge. As the planet trends warmer, a number of researchers predict that, at some point in the next two to three decades, cabernet will stop thriving in Napa.