A devastating frost in several wine regions will mean smaller harvests this year
Though it’s March that comes in like a lion, right now in France it feels like April is no less fierce as numerous wine regions battle damaging frosts. Bordeaux, Burgundy, Champagne, and the Loire and Rhône valleys have reported several nights of sub-zero temperatures.
For oenophiles who follow their favorite wine regions on social media, the images of vineyards lit by lanterns are both eerily beautiful and heart-wrenching. Last week in Chablis, one of the most northern viticulture regions and particularly known for its inhospitable climate, Domaine Christian Moreau Pere et Fils, a renowned producer,
started documenting the preparation on April 1. The domaine’s videos showed workers installing candles every other row in the vineyard in anticipation of frost, with sympathetic comments posted from wine lovers and producers across the globe. Estimates of the damage in Chablis are coming in at 80 to 90%, though a spokesman from the Bourgogne Wine Board (BIVB) relayed in an email, “We are waiting for figures. What we know is that all Bourgogne, from Chablis/Grand Auxerrois to Mâconnais has suffered. We don’t know the level of destruction within each plot. As Chardonnay was ahead of Pinot Noir, the destruction is most important for Chardonnay than Pinot Noir.”
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Similarly high estimates are being reported from the Rhône Valley, and especially Côte Rotie, and other fruit and vegetable crops are also affected. Agriculture minister Julien Denormandie has called the frost “an episode of extreme violence that has caused very significant damage.”
The traditional smudge pots or stack heaters have a large round base that contains fuel and a sort of stovepipe protruding from it from which flames and smoke emit. The prototype was developed in 1907 in Colorado by W. C. Scheu and by 1911, Scheu was manufacturing in California as orchard heaters. The inventor was put on the map during California’s great freeze of 1913 which devasted the citrus crops, and use of the pots continued for decades.
How do they work? The old-school pots burn liquid fuel like kerosene, diesel, are labor-intensive, and messy both on the ground and in the air, sending smoke and pollutants skyward. Many producers have switched to clean-burning propane or biofueled candles or paraffin heaters (Moreau uses “bougie antigel,” a natural anti-freeze candle made from vegetable wax). Either way, the principle is to either create heat or recirculate warm air via “blankets” of protective smoke. The process disrupts the flow of cold air currents falling to the ground.
Spring frosts are the most damaging because they occur when the vines have reactivated from their winter dormancy and experience “bud break,” the beginning of the vine cycle. Says the BIVB spokesman, “For this year, the problem is not the date of the frost (early April, which is natural) but the week of ‘heatwave’ we had just before Easter. Chardonnay had its budburst earlier due to those high temperatures—some 25-28 degrees Celsius (77-82° F) in the afternoons.”
Called radiation frosts, these spring frosts occur on clear and calm nights, and are characterized by the inversion layer they create when the cold air drops, and the warm ground air rises (a scientific explanation is here). That layer turns some parts of vineyards into frost traps. As a prophylactic, the lit candles or lanterns create a smoke cloud that prevents the warm- and cold-air layers from mixing.
In response to a query from a producer in Ontario, where they make ice wine, about the efficiency of the candles, Moreau responded they are “…very efficient up to minus 5 Celsius (23° F) specially when the soil and the atmosphere is very dry.” But he noted rain and snow, such as they experienced last week, caused humidity that resulted in a “50% loss of efficiency in certain parcels.”
More modern techniques are efficient but costly and include wind machines or frost fans, sprinklers and low-flying helicopters, whose propellers during a temperature inversion, can help break up the inversion layer and re-circulate warm air from above.
But, back to those tender shoots. The frost was especially cruel because an early spell of warm weather in France encouraged vines budding and growth, and then temperatures dropped to as low as -6C in last week. Once thus exposed, the buds and shoots, which contain water, freeze and basically burst, their cellular structure broken down. One producer in Bordeaux told Agence France-Presse, “It breaks like glass because there’s no water inside. It’s completely dried out, there’s no life inside.”
France suffered a significant frost in April 2017, with 17% lower yields than the year before. Other historic frosts occurred in 2003, 1997 and 1991. But Jérôme Despey, the secretary general of the French farming union and himself a winemaker in Languedoc, a southern French region, parts of which were also hard hit, told The Guardian that this year’s frosts are worse, calling it a “national phenomenon.” Vine cultivation is becoming more hazardous with climate change—not because of the April frosts, which are common, but because bud break is occurring earlier, said the BIVB spokesman.
The French government has declared it a national disaster and for the many small producers who had no insurance, it is a deeply personal disaster, especially coming on the heels of a year-long struggle during the coronavirus pandemic, the shutdown of restaurants and bars, and the ramifications of Trump-era tariffs on some French wines and fine foods, which resulted in a nearly 20% drop in exports to the U.S.
Christophe Chateau, a spokesman for the Conseil Interprofessionnel du Vin de Bordeaux, told France24, “There will be winemakers here who will be financially ruined by this … We just don’t know how many, yet.”