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Last week, an unusually late frost swept through Oregon’s Willamette Valley, as overnight temperatures dipped into the 20s. According to the newspaper the Oregonian, the wine-producing region could lose half of its grape crop.
“The buds just weren’t expecting to get whacked by frost in April,” tweeted Nicholas Kristof, an Oregon farmer and former New York Times columnist.
This is just the latest example of how increasingly unpredictable weather patterns caused by climate change are threatening the wine industry. Warmer spring temperatures have caused grapevines to bud sooner, thereby exposing them to evening temperatures that have dropped below freezing.
“It’s getting warmer in these earlier months,” Steven Schultze, a professor of geography at the University of South Alabama who has studied the effect of climate change on wine production, told Yahoo News. “There was a pretty warm March, in comparison to normal for the region. To the grapes, they don’t have a calendar, they don’t know what time of year it is. Once a certain amount of heat accumulation occurs, they’re ready to rock and roll.”
But, he cautioned, “when the buds start coming out, you’ve got to hold your breath until you get to the frost-free zone.”
Global warming has increased the number of warm days in early spring more than it has reduced the prevalence of late frosts, Schultze explained. There is an increased risk of a frost wiping out crops after they have budded.
“Warmer temperatures globally can happen, but it doesn’t mean it’s never going to get cold again in every place,” he said. “Frosts are still going to happen in Oregon and Washington.”
Early budding is not the only threat to the wine industry from climate change. More extreme and volatile weather can harm crops in a number of ways.
“Wineries across the world face devastating wildfires, polar vortexes, torrential rainfalls, hail storms, and more in addition to the constant rising temperatures year to year,” the data journalism website Stacker reported in November 2021.
In 2020, Oregon wine grape producers’ revenue decreased 34% from 2019, in large part because of wildfires that damaged crops, according to the Oregon Wine Board. Even crops that are untouched by the fires themselves can suffer from smoke blocking sunlight. Many California wines from 2020 had their taste infiltrated by wildfire smoke.
“Grapes aren’t the only crop that can be affected by smoke, but their permeable skins, and the very sensitivity that allows vintners to produce expressive, complex wines, make them uniquely vulnerable,” New York magazine recently explained.
“Wine grapes hate smoke from wildfires,” Andrew Millison, a professor of horticulture at Oregon State University, told Yahoo News. “Extreme weather events typically have a negative impact on agricultural yields. As weather becomes less predictable, then crop yields become less predictable because extreme weather can disrupt many agricultural activities, whether it’s when you plant, when you harvest, when you irrigate.
“I had all kinds of things that had started to grow in the warmth of March and then got zapped back,” he added. “My more tender plants had dieback from some of the late cold weather.”
It isn’t just heat waves and wildfires; unusually cold weather can also occur because of climate change. Because the temperature difference between the Arctic and other regions powers the jet stream, and the Arctic is warming faster than the rest of the Earth, the jet stream is weakened and more easily diverted. That can lead to more severe and prolonged cold snaps or rainfalls as the jet stream dips lower and lingers longer, as parts of the South experienced this past winter. And for each cold spell or rainy period, there’s a heat wave or dry spell somewhere else on the other side of the jet stream.
“Droughts last longer and wet periods are wetter,” Millison said. “Cold can move farther down into the continent because of this wobbly jet stream. We have more erratic spikes in temperatures, whether it’s cold or hot or wet or dry.”
All of these conditions — too much or too little rain, too much heat or cold — can harm crops, especially the notoriously fragile grape.
The vast majority of American wine comes from the West Coast. California, Oregon and Washington state have experienced increasingly frequent and severe extreme weather events in the last few years, including an ongoing years-long drought; the weeklong Pacific “heat dome,” with temperatures over 100 degrees last June; and record-setting wildfires. A 2006 study found that the United States could lose 81% of its best wine-growing areas by the end of the century. (Extreme weather aside, Canada might see a relative boom in wine production, as the range of temperatures suitable for growing grapes moves poleward.)
But the effects of climate change on the wine industry are not limited to the West Coast. All across the world, agricultural yields are expected to diminish as climate change causes more extreme and unpredictable weather and water shortages, according to the Intergovernmental Panel on Climate Change.
In 2020, France’s Burgundy region, which is legendary for its wine, experienced “an early spring that was followed by unseasonable frosts that damaged grapes on the vine,” the Guardian reported. The nearby region of Alsace has seen a shortened grape-growing season and an earlier harvest. Parts of Spain may become too hot to produce wine at all. Wine-producing countries such as Australia and Greece have also seen widespread wildfires in recent summers.
“We have so many of these time-tested places that we think of when we think of wine,” Schultze said. “We’re going to have to start questioning where our favorite wine comes from and start thinking about other places.”
On top of all this is the effect of not just global warming but the greenhouse gases that are causing the warming. Atmospheric concentrations of carbon dioxide have increased from 320 parts per million in 1960 to 420 parts per million today. Since plants take in carbon dioxide, studies suggest that if carbon dioxide concentrations continue to increase, it will affect grapes by causing faster growth, more sugar and thicker skin, which will change the flavor of wine.
Even northern U.S. states that are expected to produce more wine as they warm up are seeing the downsides of climate change in their vineyards. Last year, Michigan vineyards reportedly experienced losses from post-budding frosts in the spring and heavy rains — an increasingly prevalent problem in the Great Lakes region — in the fall.
“[Climate change] brings problems everywhere, just different problems to different places,” Schultze said.