How do helicopters help winemakers stave off freezing spring temperatures?

Ice-covered vines stretched across the hillsides around Chablis as Burgundy The region woke up Monday to temperatures of -5 C (23 F). Fruit growers fear the frost could kill off large numbers of early buds, which appeared in March when temperatures exceeded 20°C (68°F), and disrupt the entire growing season.

The frost is particularly frustrating after a similar phenomenon hit French vineyards last year, resulting in some 2 billion euros ($2.4 billion) in losses. Scientists later found that the damaging frost of 2021 was made more likely by climate change.

Before dawn on Monday, rows of candles twinkled under the frosty vines of Chablis. As the sun rose, it illuminated the ice crystals gripping the vines.

While some winegrowers use what they call candles (paraffin barrels that they light), others try to warm the vines with electric wires or sprinkle the buds with water to protect them from frost.

The helicopter method

Further south on the Côte de Beaune, helicopter pilot Caroline Schiel must wait for the aeronautical sunrise, half an hour before sunrise proper, to begin her rounds.

She was hired with her small Robinson helicopter by a local winemaker to warm the air around the vines.

“We come to the vineyards and try to determine where the inversion level is (the point at which the air is a few degrees warmer) because the temperature is reversed when there is high atmospheric pressure. At the level of the ground, it’s freezing, or below freezing, then at a certain level it starts to warm up.”

“It can be anything from five meters to 50 meters above the ground. And then we’re flying low enough that the air is sucked into the rotor system, and it’s pushed down. So we’re sucking hot air and push it The engine of the helicopter is also hot, so we blow air over the hot engine and over the vines.

Find the reversal point

“We have a team on the ground collecting temperatures on each parcel (individual sectors of the largest vineyard which often in Burgundy has several estates with different parts) and we are hovering. We have a thermometer in the helicopter , an outside air temperature reading, and we’re getting higher and higher and as soon as we see the temperature warming up, that’s the inversion level.”

“Some packages this morning were even minus five,” she told Euronews Culture.

“We flew for about two hours, taking off at 6:45 a.m..”

With the way the Burgundy is structured, it’s nearly impossible to only warm up the client’s plots when jumping from one plot to another, so the helicopter method often has the by-product of reheating the sectors of other winegrowers without being invited. It’s not always welcome even if it looks like a bonus.

“It’s a tricky topic of conversation among winemakers,” admits Schiel. “Those who don’t use helicopters place these paraffin drums every two meters in the vines, and it warms up quite well.”

“But the problem with that is you’re burning paraffin which isn’t very eco-friendly. It gets very smoky. There’s been years of flying and there’s so much smoke we had to stop stealing. It’s very beautiful, but it’s not very ecological.”

Schiel says some of the other owners are upset and accuse her and her client of “stealing” the hot air they created from the burning trash can.

“Others are happy that we’re blowing their hot air again, because obviously hot air rises,” she says.

How much does it cost?

“My client is convinced that it’s no more expensive than buying these paraffin drums, plus you have to employ staff to go out, set them up, and then light them early in the morning. They have about 8 hours of run time. combustion. They can use them for about two days, then you’ll have to replace them all again.”

Winegrowers can expect to pay around 1000 euros per hour to employ someone who will use the helicopter method. The larger the machine, the higher the cost. So it’s a matter of calculation.

There could be a hybrid solution using both and spreading paraffin trays, using less.

But in terms of fuel and footprint, Schiel is sure that while on paper helicopter versus “candle” sounds like a no-brainer, her method is less damaging to the environment.

“Some people say ‘it’s awful, you fly helicopters over the vines’, but when you have to fly in the smoke of burning paraffin, it’s not eco-friendly at all. The helicopter is much more We burn a liter of fuel per minute and then you see how many liters of paraffin they burn in the vines, you can’t compare.”

In Switzerland, local media say the country’s harvest of stone fruits such as apricots, prunes and cherries is threatened by the ice storm.

Sub-freezing temperatures are raising similar concerns about potential damage to apple orchards and other orchards in Belgium and the Netherlands.

Last year’s April frost led to what French government officials described as “probably the greatest agricultural disaster of the early 21st century”. The pattern was similar: an intense frost from April 6 to 8 after a long hot period in March.

Researchers from the World Weather Attribution group studied the effect of the 2021 frost on France’s vineyard-rich regions of Champagne, Loire Valley and Burgundy, and found that March’s heat made it particularly damaging .

The researchers concluded that warming caused by human-made emissions prompted the plants to expose their young leaves early, before an arctic cold snap reached Europe in April.