Climate change looms over France, Spain, Italy, Greece, and Southern California. These major wine regions are at risk of disappearing in the next century from excessive drought and frequent heatwaves, and despite already dealing with these difficulties, their peak has yet to come.
Under the blistering sun and high temperatures, grapes are ripening earlier than before. Within the last 40 years, grape harvests have advanced by two to three weeks. This drastic shift has led to inconsistent ripeness across vineyards and excessive heat and water stress. Grapes are a finicky fruit and the viability of vineyards is at risk as wineries are seeing smaller yields.
In an effort to combat climate change, vineyards are shifting production in major ways, either moving up hills or planting against the sun instead of towards, curtailing heat and sunlight. Though both options are costly, as wineries have to move entire vineyards. The shifting heat has also led to wine advancements in areas where grapes traditionally had difficulty growing, including England, where a sparkling wine industry is preparing to take off.
But what can small scale wineries do when they can’t make the costly choice to move? Rootstocks.
Rootstocks can be difficult to understand, so let’s break it down into a few simple parts. Rootstocks are the roots of a grapevine that are stronger and more resistant to drought, disease, and soil types than other grapevine roots. What growers learned is that they can essentially chop these strong root systems (rootstocks) off one vine and combine them to a weaker grape shoot (scion) to make the ideal grape to grow in their region.
The grafting of roots onto other grape varieties is nothing new for vineyards. Rootstocks originated in 1887, following the phylloxera crisis that plagued Europe's wineries, when Pierre Viala embarked on a mission to cure these diseased vines. After months of traveling across North America searching for a root cure, he met Thomas Volney Munson, a vine-connoisier of sorts. Munson knew vines, habitats, and soils, and through his knowledge guided Viala to Dog Ridge, Texas. There, Viala found alkaline, chalky soil abundant with healthy and strong grapevines. After writing to France of his findings, 15 wagons of vine cuttings, which we now know as rootstocks, made their way across the Atlantic–saving Europe and the beloved wine we know today from crisis (in summary).
Soil plays a crucial role in not only the flavor but the growth and survival of grapevines. While previously rootstocks were chosen to combat disease, they’re also fit to overcome soil issues such as texture, pH, density, and now drought–a more frequent occurrence due to climate change. Growers are able to select grapevines more resistant to these environmental adversities to help maintain or even increase their grape varietal growth.
Rootstock’s adversity makes it a more accessible choice for small scale wineries that don’t have the means to move their whole vineyards or purchase land in the newly blooming wine sanctuaries. While rootstocks will alter the growth and amount of yield (either positively or negatively), they serve as an immediate solution for the impending threat of climate change on wine.
Unti Vineyard, located in the Dry Creek Valley of Sonoma County, California, has adapted rootstocks to fit classic Mediterranean wines to California’s dry climate. Their rare choice to grow Italian Sangiovese grapes in California is made possible by the use of 110-R rootstock, which is adaptable to drought and dry, stony soil. Through this cultivation, Unti’s Sangiovese vintage has been able to advance well in age, creating a final complex and depth full-bodied wine–deomonstrating just one way wineries can use rootstocks to their advantage.
The Future Effects of Climate Change on Wine
Researchers are currently studying the long term effects of various rootstocks and climate change. While stronger than traditional vines, finding the proper rootstock for each region is proving to be difficult, as it takes three to seven years for vines to grow and see results. With the most commonly used rootstocks being genetically similar, there is a threat of future havoc if vines are not switched to a more diverse range of rootstocks fit for more difficult weather conditions.
It’s also questioned whether rootstock can alter the taste of wine, since soil is a major factor for grape flavor and it’s the roots that pull these nutrients up. Though, research seems to show rootstocks actually have little effect on the final flavor of wine. Beyond affecting the total yield and time to bring grapes to proper ripeness, it’s mostly the soil that matters, not the root itself. But even with the use of rootstock to combat climate change, the flavors we know and love of wine today will differ.
Flavors will change as traditional wine regions dry out, even for wineries that stay and use rootstock, as the soil affects flavors and heat enhances sugar and alcohol content. Other major wineries with the means to move will shift the trending flavors and preferences of consumers. Plus, wineries in unlikely regions such as Argentina and Chile, where wine is already advancing in quality and vines are still grown with their own-root, may take off for their unique flavor profiles and obtain a major hold of the wine market.
Just as wine overcame the phylloxera crisis, wine (and our flavor preferences) will learn to adapt to a warmer, drier future.
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