Michigan winemakers have a new climate worry: More wildfire smoke

Last month, when wildfire smoke enveloped the skies over northern Michigan, Kasey Wierzba was struck by how the vineyard at Shady Lane Cellars in Suttons Bay looked otherworldly.

“The whole vineyard was shrouded in a pinky, peachy haze, making visibility extremely limited,” recalled Wierzba, who serves as the general manager and executive winemaker at Shady Lane Cellars, a winery on the “little finger” of Michigan’s Leelanau Peninsula, renowned for its wine production.

Wierzba also pondered the potential effects of the strong smoke on the grapes, a concern becoming more common in the wine industry as global warming heightens the frequency and severity of wildfires. Fortunately, she and other local grape growers were not significantly affected, as the most severe wildfires were distant, burning in Canada and Minnesota. The smoke cleared quickly, and it remains early in the growing season. However, climate change may bring such dangers closer in the future.

The state’s nearly $9 billion wine industry could face challenges adapting to the effects of smoke on grapes, a difficulty already seen in wine regions like the West Coast and Australia.

Extended smoke exposure can cause grapes to develop “smoke taint,” leading to undesirable flavors in the finished wines, described as anything from barbecued food to burnt bacon.

Wierzba expressed confidence that the early stage of the growing season means finished wines won’t be impacted. At this time of year, the grapes resemble small pellets, known as the “buckshot berry stage,” due to their size.

Wierzba plans to send grape samples to laboratories if smoke returns, to detect compounds from wildfire smoke. “This incident made me realize the importance of being prepared,” she said.

While tests can be useful, Paolo Sabbatini, a viticulture professor at Michigan State University, noted that measuring smoke damage before wine production is challenging. Smoke compounds bind to grape skins and tissues, revealing smoke taint flavors only during fermentation.

“You need to wait for the finished wine. So during the season, unless your vineyard catches on fire and you see damage on the berries after a smoke event, you can’t even measure anything,” he said.

Sabbatini received 10 calls from Michigan grape growers and winemakers concerned about smoke effects. He remains “pretty confident” that the smoke exposure wasn’t prolonged enough to harm the grapes, given the ongoing fires in Ontario and Minnesota, which have destroyed over 64,000 acres according to the U.S. Forest Service.

Local growers felt fortunate that the smoke didn’t occur when grapes are most sensitive during their color-changing period in the fall.

“Our fruit is still very immature, going through cell division, so the cells, clusters, and berries aren’t fully formed yet,” said Brian Hosmer, winemaker at Chateau Chantal on Old Mission Peninsula, a northern Michigan wine hotspot.

Concerns about smoke taint are increasing globally, as larger, hotter wildfires approach vineyards. In southwestern France, fires have burned over 160 square miles of forest near Bordeaux, threatening the renowned wine region.

“We’re talking about places where the fire is literally up to the edge of the vineyards, or even a couple miles away, where they’re getting ash falling directly on the fruit,” Hosmer said.

As climate change leads to hotter, drier summers, the likelihood of wildfires and widespread smoke increases, exposing more areas to smoke taint, according to Ben Montpetit, chair of the department of viticulture and enology at the University of California, Davis, a leader in smoke taint research.

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Montpetit explained that there are no simple solutions to smoke taint. Treatments to remove the unwanted flavors could affect wine quality or introduce new tastes. Increased awareness has led to more state and federal support for research, including a directive in the latest U.S. farm bill draft for further study into wine grapes and wildfire smoke exposure. However, Montpetit believes smoke taint will persist as a challenge.

“As much as we can prepare, there are going to be fires in the future, and unfortunately, they will impact wine regions,” Montpetit said.

Grape growers are adapting to environmental changes, from drifting wildfire smoke to increasingly variable weather. Studies on climate change impacts on Michigan’s wine region highlight early spring frosts that can damage vines and rising temperatures during the growing season.

Those in the industry view adaptation as part of their work. Centuries ago, winemakers were drawn to the region to benefit from the extended growing season provided by Lake Michigan.

“It’s always challenging. It’s farming. It’s legalized gambling,” Hosmer from Chateau Chantal remarked. He isn’t worried about the impact of the recent smoke but acknowledges that warmer summers prompt thoughts about local fire risks around vineyards.

Andy Fles, vineyard manager for Shady Lane Cellars, noted that this year has already posed challenges with extreme precipitation and temperature changes in northern Michigan.

“Global warming doesn’t mean everywhere is going to be warmer every single year,” he said. “I think what it means for us is that it’s climate chaos, and it’s very hard to predict what is going to happen.”

And that includes wildfire smoke.

“It’s something that you can’t necessarily control, which is frustrating at times,” Fles said. “So this is just a new hurdle, and we’ll find ways to deal with it when we have to.”