When wildfire smoke blanketed northern Michigan skies earlier this month, Kasey Wierzba thought the vineyard at Shady Lane Cellars in Suttons Bay looked like a different planet.
“That kind of pinky, peachy haze really was filtering through the whole vineyard. The visibility was really minimal,” said Wierzba, who is the general manager and executive winemaker at Shady Lane Cellars.
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Wierzba also thought about how the smoke might impact the grapes, something that the wine industry is becoming more familiar with as wildfires increase in frequency and intensity.
When grapes get exposed to smoke for an extended amount of time, finished wines can develop what’s known as “smoke taint” — unwanted flavors that have been described as anything from barbecue to burnt bacon.
It’s not a major concern for grape growers in northern Michigan this year, given the short time that smoke lingered in the region, the sheer distance from the worst of the fires in Canada, and how early in the season the crop is.
But as climate change is expected to fuel more intense and frequent wildfires, the state’s nearly $9 billion wine industry could one day face challenges with smoke impacts on grapes.
“I think having the smoke incident at this time in the grape growing, when they wouldn’t be affected, spurred me to think, ‘Wow, I need to be prepared,’” Wierzba said.
The science of smoke taint
Because it’s early in the growing season, Wierzba said she’s confident there won’t have any impact on finished wines. The grapes are shaped like small pellets at this point of the year, known as the “buckshot berry stage” because they resemble the size of bullets used for hunting deer.
Still, when smoke hits again, Wierzba said she’ll consider sending grape samples to labs that could detect the compounds associated with wildfire smoke.
Tests can help, but it’s generally difficult to measure damage from smoke before wine is produced, said Paolo Sabbatini, a viticulture professor at Michigan State University. Smoke compounds bind with the grape skin and tissues and the flavors associated with smoke taint only come through during the fermentation process.
“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 grape growers and winemakers around Michigan with questions about smoke impacts. But he said he’s “pretty confident” that there wasn’t enough smoke exposure over a long enough period of time for grapes to be impacted by this month’s haze.
Local growers said it was fortunate that smoke didn’t hit the region during the key time that grapes change color in the fall — the period that grapes are typically most sensitive to smoke impacts.
“We are sitting with our fruit still at a very immature stage, when we’re still going through cell division. So all of the cells, and the cluster, and the berries aren’t formed yet,” said Brian Hosmer, winemaker at Chateau Chantal on Old Mission Peninsula.
Smoke taint is a rising concern in places like the West Coast and Australia, which see more frequent and intense wildfires closer to vineyards.
“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.
But as climate change fuels the hotter, drier summers that increases the likelihood of wildfire events and widespread smoke, the places exposed to smoke taint are also increasing, said Ben Montpetit, chair of the University of California Davis’s department of viticulture and enology. The program is one of the country’s leaders in this area of research.
There aren’t simple solutions to smoke taint, Montpetit said. Treatments to remove some of the unwanted flavors could impact wine quality or introduce other tastes.
“As much as we can prepare, there are going to be fires in the future, and unfortunately, they will impact wine regions,” Montpetit said.
Adjusting to "climate chaos"
Grape growers said they’re learning to adapt to multiple changes in the environment, from drifting wildfire smoke to increasingly variable weather conditions. Studies looking at climate change impacts on Michigan’s wine region cite early spring frosts that can damage vines and hotter temperatures during the growing season.
Those in this industry said adaptation is part of the job. After all, winemakers first flocked to the region centuries ago to take advantage of the extended growing season that Lake Michigan provides.
“It's always challenging. It's farming. It's legalized gambling,” Hosmer with Chateau Chantal said. He said he’s not concerned about impacts from this recent smoke, but a trend of warmer summers “definitely makes us think about what’s going on in the woods around our vineyards,” in terms of local fire danger.
Andy Fles, vineyard manager for Shady Lane Cellars, said it’s already been a tough growing season in northern Michigan this year between extreme precipitation and fluctuating temperatures.
“Global warming doesn't mean everywhere is going to be warmer every single year. 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,” he said.
And that includes wildfire smoke.
“But 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.”
