This story was originally published by Wired and appears here as part of the Climate Desk collaboration.

Unless you’ve got a cellar stockpiled to last you the rest of your life, climate change is probably coming for your favourite wine. Temperature fluctuations during the growing season create the flavours, alcohol content, and even colour of your preferred fermented grape juice — producing a beautiful ballet in a bottle. So as global temperatures soar and water availability in many regions plummets, the characteristics of individual wines are changing.

Up to 70 per cent of today’s wine regions could be at substantial risk of losing suitability for production if the world warms more than 2 C, a new paper finds. (That’s the Paris Agreement’s absolute limit for warming above pre-industrial temperatures.) Due to ever-fiercer droughts and heat waves, 90 per cent of the traditional coastal and lowland wine-growing regions of Spain, Italy, Greece and southern California could be at existential risk by the end of the century. Meanwhile, rising temperatures are opening up new regions to growing, like the southern United Kingdom, as wine production generally shifts to higher latitudes and altitudes, where it’s cooler.

“It doesn’t mean that the wine-growing disappears — and that’s an important caveat — but it means that it can get a lot more challenging,” says viticulturist Greg Gambetta of Bordeaux Sciences Agro and the Institute of Science of Vine and Wine and lead author of the review paper in Nature Reviews Earth and Environment. “There’s actually a lot of room for adaptation for wine growers — if the warming is limited. This is true for most regions.”

Still, climate change will make wine-making increasingly difficult in many places. The paper notes that by the end of this century, the net suitable area for wine production in California could decline by up to 50 per cent. The suitable area across Europe’s traditional wine-producing regions could fall by 20 to 70 per cent, depending on how much warming we end up with. Up to 65 per cent of Australia's traditional vineyards might become unsuitable.

As temperatures rise, a grape plant reacts in complex ways. “You need a degree of heat to get through the ripening phase, to get sugar accumulation, and then also get the ideal amount of development of some of these secondary compounds like anthocyanins and tannins — all the things that make wine exciting and interesting and have good mouthfeel,” says Elisabeth Forrestel, a viticulturist and ecologist at UC Davis who wasn’t involved in the new paper. “It’s when you exceed certain temperatures that it becomes problematic for the grapes.”

Intense and persistent heat waves, for instance, can sunburn the fruit, greatly reducing its quality. But before that, higher temperatures desiccate the grapes, concentrating the sugars. The more sugar, the higher the alcohol content. If you’re drinking wine to get drunk, climate change will make wines more efficient for you, sure enough. “Depending on who you are, where you come from, this can be a bad thing,” says Gambetta. “If you have a region that’s always defined a style in a certain way, then that’s going to change the wine.”

More subtly, heat influences volatile compounds that turn into gas — that’s the “nose” you get when tasting wine — which breaks down under higher temperatures. “The profiles tend to get pushed to what sensory scientists would call the ‘cooked’ side of the spectrum: more jammy, or like cooked fruit,” says Gambetta. “This can be a good thing. Some people like wines like this and it’s fine. So it all has to do with the identity of a region.”

The ideal climate for winemaking is warm days and cool nights, with conditions heating and cooling the grapes. But climate change is altering that cycle in dramatic ways. “It’s actually the nights that are warming faster than the days,” says Forrestel. “You don’t get the cooling of the fruit in the nighttime. And then when you exceed ideal temperatures during the day, you actually have degradation of a lot of the compounds that are important.”

Enjoy your favourite wine before climate change destroys it. #ClimateChange #ExtremeHeat #Winemaking #RisingTemperatures

Even in the absence of drought, higher temperatures make the plants lose more water. That, in turn, reduces the yield of grapes, meaning a winemaker would end up with less juice to work with. Paired with drought, yields decline even further. “You take Bordeaux, where I work, the rainfall has been pretty steady if you look over the past 100 years,” Gambetta says. “But the fact that the temperatures are going up and up and up, that drives more water use out of the agricultural system.”

Vineyards can also receive too much water. As the atmosphere warms, it can hold more moisture, which is supercharging rainstorms, hence the catastrophic flooding we’re already seeing around the world. If too much rainwater sits in a vineyard for too long, it deprives the vines’ roots of oxygen.

Still, the grape plant is surprisingly hardy: Without supplemental irrigation, typical Mediterranean varieties like grenache can churn out good yields and make good wines with as little as 14 inches of rain a year. A vine might be able to ride out a drought with lower yields, or by dropping its leaves, known as defoliation. That won’t kill the vine itself, so it can bounce back once rains return.

But as climate change makes droughts more common and more intense, some winemaking regions are feeling the strain. “In 2022, which was outrageous by all definitions in Europe — in Portugal and parts of Spain — they had seriously stunted vines, defoliated vines,” says Gambetta. “Then you can get into this dangerous territory where you have not only really catastrophic effects that season, but you can get carryover effects to subsequent seasons.”

To adapt, vineyards can, of course, begin irrigating. But that comes with added costs and potentially puts a strain on local freshwater supplies: If drought has gripped a region, everyone else is going to need more water, too. And even then, the plants will have to contend with Europe’s intensifying heat waves.

Another option is for vineyards to shift north as the climate warms. Indeed, the new paper notes that in the northerly regions of Europe and North America, suitable land for winemaking could increase between 80 and 200 per cent, depending on the amount of eventual warming. Winemaking is now booming in the southern U.K., for instance, as well as in Oregon and Washington state in the U.S.

But that’s no guarantee that climate change won’t make a mess of operations in those territories as well: The Pacific Northwest has in recent years been wilting under extraordinary heat waves, with temperatures climbing above 110 F for days at a time. The West Coast’s increasingly massive wildfires are also smothering vineyards in smoke, tainting wines: Campfire flavours are for smores, not merlots.

At the same time, other supply chain hiccups are conspiring with climate change to drive up the price of your favourite wine. Corks come from the bark of cork trees, which is repeatedly harvested over the lifetime of the plant. But during droughts, the trees dry out too much for crews to peel off the bark without killing them. The wine industry has also been grappling with rising prices of the glass used to make bottles.

To help winemakers adapt, scientists are experimenting with different tricks to cool the plants. Cover crops growing under the grapes help cool the fruit, for instance. “If you have bare soils on your vineyard floor, you get a lot of re-radiation — your soils heat up a lot and then reflect heat back into the canopy,” says Forrestel. “I think we’re just beginning to understand the impacts of some of these truly extreme events because they’re more recent, and becoming more frequent.”

While winegrowers can’t change the weather, they can change their plants. Reducing the amount of leaf biomass reduces the amount of water the plant loses in a heat wave, and “canopy management” can guide the remaining leaves to more purposefully shade the berries from the sun. And winegrowers are already experimenting with different varieties of grape, especially those known to be drought- and heat-tolerant, in different regions. Developing varieties that have deeper root systems means the plants can tap into water deeper in the soil.

“Changing the variety is a huge, huge lever, because varieties have huge variation in how they behave,” says Gambetta. But that’s easier said than done. In Bordeaux, there’s a long history of exceptional wines — a long history that has until now unfolded across a fairly stable climate. They’ve done massive studies on new varieties. “But if you look at: Has there been an uptake? Do growers change? The answer is clearly no, they don’t,” says Gambetta. “They can’t necessarily just make this brand new wine and go, ‘Hey, listen, here’s my new wine, and it’s gonna sell like hotcakes. Because whole regions are based on these identities.”

This is the inherent contradiction of the grape. Winemakers pride themselves on a consistent product that loyal customers demand. But the grape plant is actually a hardy crop that can withstand change — that’s why it can grow all across the planet, from Bordeaux to Napa, on down to Chile and South Africa.

“It just is a plant that has a huge swath of climates that it grows within,” says Gambetta. “But it doesn’t mean that climate change is not going to present serious challenges, especially to these traditional winegrowing regions.”

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