Wine and Wildfires: A Journalistic Essay of Climate Change, Grapes, and Science (PRAx 2024-2025 fellowship project)

 

Imagine you are a winemaker overlooking your 10 acre vineyard. These vines have never failed to produce the caviar of grapes, used to make a wine that reflects the land as much as it does your craft. Just before harvest, a slight shift in the wind blows in wildfire smoke, turning the sky hazy yellow orange. While these grapes are seemingly unscathed, the smoke catalyzes invisible chemical reactions in your grapes. You are told they cannot be used for wine but must be harvested and dropped to compost in place, as you suffer the crushing loss of watching your year-long toils turn to compost.

This worst case scenario has been a shared experience of grape growers and wine makers facing unprecedented wildfire events in recent years. Post 2020 wildfire season, the Oregon wine industry lost over two billion dollars and ten thousand jobs, largely attributed to grapes and wine rendered unusable from wildfire smoke. This is why my research is developing the first pre-harvest protective coating to shield wine grapes from wildfire smoke.

The first grape bunches looked like tiny flowers, stiff green stems topped with beads. I strolled through rows of vines inspecting the miniature green grapes I was about to spray with a smoke-protective coating.  Outfitted with a heavy backpack sprayer containing 5 gallons of liquid, I slowly moved amongst the vines, pushing away blankets of foliar leaves to douse the tight clusters of pea-sized grapes underneath.

The next time I saw the grapes, two weeks later, it looked like someone had come through the vineyard with a purple paintbrush. Dark purple grapes flashed against the foliage, presenting tight, lush clusters of grapes and stems. It was at this point that we applied another round of spray coating. As the thick, milky mixture dripped slowly from bunches, I wondered if it would be robust enough – or even still on the growing grapes – upon vine smoking in a couple of weeks.

In the past ten years, the Pacific Northwest has faced increasingly more intense wildfires. Years are cyclic, but trend up; every few years, another monster firestorm hits. In past years, smoke from these wildfires has encroached on the home of Oregon wine, especially Oregon Pinot noir.

So how does the smoke effect grapes? When woody material is burned, the large, complex structural molecules are disintegrated into individual, cyclic molecules we call volatile phenols. It is like cutting up the multi-ringed plastic casing on a case of sodas into individual plastic rings. These individual molecules are volatile. And small. The combination allows them to land on grape surfaces and weasel their way through the outer waxy protective layers and skin of the grape. These volatile phenols carry ashy, medicinal, burnt, or rubbery flavors and aromas that are released during or after winemaking.

Tracking smoke exposure in grapes is complex and unpredictable. When a smoke volatile phenol enters a grape, it is like putting a quarter into a gumball machine. The grape can convert the volatile phenol into a variety of chemical products, making compounds difficult to trace. It is like receiving a randomly colored gumball from a gumball machine and trying to figure out which quarter it came from. Additionally, it is almost impossible to predict how and if this kaleidoscope of chemical reactions will influence the final wine. The ongoing discovery of conversion compounds makes decision making difficult and business decisions blurry. What we are trying to do is prevent the quarter from entering the gumball machine in the first place; we are developing a coating to get between smoke and the grape.

Granted Smoke is not mother nature’s first stab at wine grapes. In fact, in some ways climate change has been favorable for the Oregon grape industry. Greg Jones, wine climatologist explains how in the 50’s, you just couldn’t grow grapes in Oregon. The climate was prohibitive, with risk of cold in winter and spring. Over the years, the climate has turned warmer and dryer, with less frost and a longer growing season. However growers still face climate extremes and speak of extreme heat shriveling their grapes, or flash hailstorms flattening sections of vines. These challenges can be devastating, but they can also be identified and have a more concrete outcome. However, smoke has brought something much more sinister. A phantom chemical reaction. The pretense of normalcy.

It was time to understand if our barrier coating would shield the Pinot noir grapes from simulated wildfire smoke. The moon had risen over the small research vineyard in Medford, Oregon, casting a hazy light over the vineyard otherwise blanketed in darkness between hills. Moonlight intermingled with two searchlights lighting the research station to cast the vines into chiaroscuro.

We assembled tent enclosures around the vines using large plastic tarps. Douglass Fir chips were smoldered in a barbeque, and smoke was directed into each enclosure using pipes. The vineyard smelled of campfire, as our team sat around laughing and telling stories during the night. Meanwhile, in the tent enclosures, the grapes were surrounded by smoke. 

A portion of the grapes were coated with our barrier coating, but was it enough to withstand this treatment of direct smoke? In a way, we are trying to trap a ghost with the coating. We could not see it working. We could not see what it was blocking. We would wait until the grapes were harvested in mid-September and bring them back to the lab to analyze which smoke compounds remained in the grapes.

Smoke can affect grapes and wine on a spectrum; from just noticing something “different” but not necessarily bad, to causing unpalatable ashy aftertastes. Also, consumers may accept smoke-exposed wine if wineries use marketing to explain smoke as a feature of the growing season, rather than as a detriment. Furthermore, how and if certain wines will be impacted depends on the timing of smoke, the distance of smoke, the varieties of grapes, and fermentation techniques. It is incorrect, and unfair to the grapes and their growers, to generalize all grapes exposed to smoke as tainted. However, our work on this coating is a step closer to avoiding another 2020 and being able to shield the Oregon wine industry from future wildfire events.

Oregon wine has been etched and molded in the last 50 years of nurturing and learning, warming climates and changing soils, extreme heat, and extreme cold. The result is a product so inseparable from the Earth in which it grew, and from the people who crafted it. As climate extremes manifest in years of extreme smoke, Oregon grapes also face these conditions. Smoke poses new challenges but also new possibilities. And with the help of scientists, winegrowers, and winemakers, Oregon wine will prove resilient.