Cabernet grapes at the UC Davis Oakville research station in Napa Valley. Credit: Katarina Zimmer
Soon after the devastating Glass Fire sparked in California’s Napa Valley in September 2020, wine chemist Anita Oberholster’s inbox was brimming with hundreds of emails from panicked viticulturists. They wanted to know if they could harvest their grapes without a dreaded effect on their wine: the odious ashtray flavor known as smoke taint.
Oberholster, of the University of California, Davis, could only tell them, “Maybe.”
Industry laboratories were slammed with grape samples to test, with wait times of up to six weeks. Growers didn’t know whether it was worth harvesting their crops. Eight percent of California wine grapes in 2020 were left to rot.
Winemakers are no strangers to the vicissitudes wrought by climate change. Warmer temperatures have been a boon to some in cooler regions who are rejoicing over riper berries — but devastating to others. Scorching heat waves, wildfires and other climate-driven calamities have ruined harvests in Europe, North America, Australia and elsewhere.
And as 2020 showed, climate change can take its toll on grapes without directly destroying them. Wildfires and warmer temperatures can transform the flavor of wine, whose quality and very identity depends on the delicate chemistry of grapes and the conditions they’re grown in. Many growers and winemakers are increasingly concerned that climate change is robbing wines of their defining flavors, even spoiling vintages entirely.
“That’s the big worry,” says Karen MacNeil, a wine expert living in Napa Valley and author of The Wine Bible. “That’s the heartbeat of wine — it’s connected to its place.”
The greatest challenge that climate change brings to winemaking is unpredictability, MacNeil says. Producers used to know which varieties to grow, how to grow them, when to harvest the berries and how to ferment them to produce a consistent, quality wine — but today, every step is up in the air. This growing recognition is spurring researchers and winemakers to find ways to preserve beloved grape varieties and their unique qualities under the shifting and capricious conditions of today’s warming world.
To learn about the threats to our favorite beverage, we spoke with wine experts from two renowned wine regions — Bordeaux in France and California — to understand how climate change is uprooting their traditional vines and wines, and traveled to the University of California, Davis, and nearby Napa Valley in late 2021 to speak with scientists, growers and winemakers.
We were treated to an inside look at how every stage of winemaking is transforming to preserve desired flavors and aromas — and yes, got to taste a lot of wine, from the finest Cabernet Sauvignon to samples spoiled by smoke and scorching heat.