Illustration by Various Media
The National Weather Service began recording temperature across the U.S. in 1901. The year 2016 was the warmest, followed by 2020. This past decade was the warmest 10-year span on record.
Vintage write-ups have been filled with notes of extremes in addition to record-breaking heat: drought, humidity, fires. Grape farmers and winemakers across regions are faced with the task of growing quality fruit and making sound wine in unprecedented conditions.
In 2021, all around California, grape farmers prepared for a quick harvest after a year of extreme heat, hoping to pick grapes with adequate acid. Over in the Northeast, a steady rise in temperature has led to humidity and increased disease pressure.
Terroir is tied to more than just soil, flora and fauna. It is the taste of the climatic condition in which the grapes were grown. Fine-tuned palates can detect the nuances among wines grown on the same site in a cool, hot, wet or dry season.
As the climate changes, the fragile nature of Vitis vinifera is highlighted and the boundaries of ideal growing regions are being pushed. Some U.S. growers—and potentially some in the European Union, which recently approved their use—are looking to hybrid grapes and their non-vinifera parents as more stable vehicles not just to translate their terroir, but also to respect the environment.
Organic and Sustainable Practices
Timothy Martinson is a senior extension associate for the Viticulture and Enology program at Cornell University. He is also an outreach coordinator for VitisGen2, an effort that spans institutions. Part of his work is to identify genetic markers for marker-assisted selection when considering parentage for hybrid grapes.
“The key difficulties in the vineyard due to climate change are a change in rainfall, an increase in temperature and disease pressure,” says Martinson.
He explains an increase in temperature on the West Coast has restricted water access and accelerated wildfires. Growing areas on the East Coast and pockets of the Midwest, on the other hand, have experienced an increase of rainfall that, in combination with overall higher temperatures, has led to elevated levels of humidity.
“A combo of high humidity and higher temps drive these late-season rots,” says Martinson. “Warmer nights extending into ripening season change the character of fruit and lead to more late-season disease pressure like powdery mildew, downy mildew, Phomopsis, Botrytis and fruit rots. Long-term, we need to move to different varieties. A key gap in some sustainability programs is that we are starting with plants that are highly susceptible to these diseases.”
Managing these diseases becomes an even bigger challenge when you consider that some of the means to do so carry their own dangers. Fungicides and herbicides can disrupt the healthy ecosystems around the vineyards and harm the workers handling the chemicals. Even organic sprays made from copper sulfate can leach into the ground.
That means many growers are looking for other ways to deal with these conditions.
“All major European varieties did not evolve with powdery mildew, downy mildew or Phomopsis as a pathogen,” says Martinson. “In contrast, we have about 10–15 species native to U.S., grapes that coevolved with these diseases so they formed resistance.”
And plants with this sort of resistance offer another benefit: Organic practices of not churning the soil, or no-till farming, and planting cover crops can offset the carbon emissions of the vineyard. But these practices are easiest to impart when the vines are well suited to their growing environment, needing less intervention in the soil.