ST. HELENA, Calif. – The estate house grounds at Spottswoode Winery look like a postcard from a 19th-century dream. A sprawling Victorian mansion commands a view of lush gardens, a shimmering swimming pool and 45 acres of grape-filled vines that soon will be harvested.

A very 21st-century menace casts a shadow over this sunny scene: climate change.

Soaring temperatures, irregular rain patterns and the ever-present threat of fires cause winery owners here and around the world to adopt aggressive strategies to safeguard their livelihoods. Tactics include experimenting with new varieties of grapes, finding new ways to maximize water use and even seeking out land in areas that used to be too cold for vineyards.

“My parents started this winery, and I’m looking at passing it down to the next generation,” says Beth Novak Milliken, 58, CEO of Spottswoode Estate Vineyard and Winery, whose Cabernet Sauvignon can fetch $90 to $225 a bottle. "But to do that, I now have to plan ahead in a way I never thought I’d have to."

From 2012 to 2014, the winery in Napa County north of the San Francisco Bay Area experienced about six days over 98.6 degrees during each April-through-October growing season. That number rocketed to 17 days in 2015 and a record 21 in 2017 – when temperatures hit a desert-like 118 degrees on a few occasions.

The level of heat stresses the vines in unprecedented ways, sending temperatures inside the grapes soaring upward of 150 degrees, risking the collapse of the delicate ripening and maturation process that is crucial to high-end winemaking.

“In 2017, we saw our vineyard go into stasis, a period where chemically nothing was happening, which was unheard of,” says Aron Weinkauf, 43, Spottswoode’s winemaker and vineyard manager.

“This is not a crop you get a few shots at a year, like vegetables. It’s just one chance each year to get it right,” he says. “That translates to very expensive farming. So we have to do everything we can to ensure the longevity of this vineyard despite the huge pressure of climate change.”

Measures include extensively shading the vineyards, developing cover crops that can help with either drought or flooding, and planting experimental rootstocks – the foundational root that lies below the ground – that may be better suited to higher temperatures.

“People around these parts are no longer talking about climate change as an 'if' or a 'when,' ” Novak Milliken says. “It’s here.”

And it’s global. Winemakers in both hemispheres are adapting to new climate norms that have jeopardized their harvests.

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In South Africa, a severe drought in May 2018 caused a 15% drop in the grape harvest, sending prices up and wineries scrambling to find new ways to leverage technology to manage irrigation, says Wanda Augustyn of VinPro, a trade association that represents South African wine producers.

In Spain, renowned winemakers Familia Torres have begun buying land high in the foothills of the Pyrenees mountains that border France, a zone whose consistently cool temperatures once made the area inhospitable to growing grapes but that climate change has made attractive.

In France, the hallowed home of the cultivated grape, the industry’s strict governing body, the INAO, decreed last year that winemakers could experiment with new grape varietals that could be used to balance out juice from harvests increasingly disrupted by hotter summers that lead to earlier cultivation and even increased alcohol levels.

Though winemaking’s ancestral heart may be rooted in European soil, its future has always been in the New World, says Karl Storchmann, professor of economics at New York University and editor of the Journal of Wine Economics.

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The USA is the world’s largest retail wine market, valued at $70 billion in 2018, and the fourth-largest wine-producing nation behind Italy, Spain and France. Climate change could reshape those numbers, Storchmann says.

“Fine-wine quality and prices are extraordinarily sensitive to fluctuations in the weather and the year in which the grapes were grown,” he says. “Wine is an ‘experience’ good – that is, its quality cannot be ascertained before consumption.”

Many winemakers look north. Storchmann says he sees vineyard land prices in southern France drop while prices in the north rise.

“The same can be seen in Canada and the United Kingdom,” he says. “Northern regions are winning, while southern regions are losing, and vice versa in the Southern Hemisphere.”

Christine Clair is winery director at Willamette Valley Vineyards in Turner, Oregon, just south of Salem. Although the region is known for its cool climate, which is especially hospitable to thin-skinned varietals such as pinot noir, Clair and her team have over the past few years looked to plant at higher elevations – moving from below 500 feet to 500 to 800 feet – as the lower zones heat up.

The winery’s vines have produced higher crop yields because of new periods of unusual heat. “The accounting team really likes it,” Clair says. “We can farm more fruit.”

But she’s aware that if warming trends continue, “our winery will have to look for cooler spots to maintain the stylistic goals we have for our product.”

Her team remains vigilant of wildfires, which have been stoked across the West because of higher temperatures and greater aridity. Fires damaged some California wineries in recent years, and the smoke, if dense and persistent enough, can permeate the berry and alter its flavor.

“The past few vintages, we’ve had significant losses due to wine grapes getting affected by smoke,” Clair says. “There’s no question there's more for us to think about these days.”

Looking for cooler zones for vines

Ultimately, consumers might need to train their palates to appreciate new wine varietals.

“People can’t expect to buy the same product year in and year out and not expect change,” says Gregory Jones, a wine industry authority and director of the Evenstad Center for Wine Education at Linfield College in McMinnville, Oregon. “As climate change evolves, consumers need to embrace the newness of what might come.”

Jones notes that of the 5,000 known grape varietals, only about 20 are produced worldwide, leaving thousands of others to experiment with as the climate challenges the existing stock.

“I’m optimistic because there’s a lot of adaptive capability in this industry,” says Jones, who addressed a gathering of wine experts in Sweden, where cooler-climate wine production was explored. “But I am pessimistic because at some point, the climate will be too warm for certain things, wine or otherwise. So being proactive is a big piece of this.”

Ria D’Aversa, director of ranch operations at McEvoy Ranch, says climate change is “keeping us all on our toes.”

McEvoy, which produces wine and olive oil, is in the Petaluma Gap, an area north of Napa and Sonoma counties in California's wine country and much closer to the cooling breezes and frequent fog generated off the Pacific Ocean.

For years, McEvoy has produced pinot noir that benefited from those temperature-reducing winds, but lately, “it’s been getting extremely hot, which means we have to think, what should be the next step?” D’Aversa says.

That could mean experimenting with new varietals that can cope with temperature swings, or buying land higher up in the gap to hedge against temperature spikes. “We just have to deal with the ups and downs more,” D’Aversa says. “With Mother Nature, you don’t have control.”

S. Kaan Kurtural is a viticulture expert at the University of California, Davis, a center for wine science. He says the way the climate has affected this industry over the past few years has “shocked me. It’s not going to be business as usual.”

He’s conducting an experiment with Napa’s Beckstoffer Vineyards that involves planting 3,600 Cabernet plants that are made up of 100 different rootstock and clone combinations. The idea is for Kurtural to spend the next eight years making wine from this plot to see whether some of the experimental crop proves more heat- or drought-resistant.

“Anyone who farms anything has known that the climate has been shifting for a while, but now there’s an economic necessity to take action,” Kurtural says. “We’re looking to the future, because by 2050, we’ll have even hotter temperatures and more greenhouse gases.”

At Larkmead Vineyards in Napa Valley, winemaker Dan Petroski has no interest in waiting to see what the future holds. “It’s all happening quicker than we thought, and I have a fiduciary responsibility to the owners of this winery to see where this business is going,” he says.

Given that Larkmead is known for Cabernet wines that can sell for upward of $350 a bottle, he is eager to see what grapes can be developed that could be used to blend with Cabernet to cut any heat-induced acidity while maintaining the label’s signature flavor.

To that end, he’s getting ready to plant an experimental 3-acre parcel with more heat-resistant varietals at a cost of $75,000. It’s a gamble, but one he says he has to take.

“I wouldn’t be doing my job if I started to think about things like this 20 years from now,” he says.

One family's winery dream at risk

About 6 miles south of Larkmead Vineyards, Spottswoode winemaker Aron Weinkauf walks through the rows of deep purple Cabernet grapes that are responsible for the winery’s burnished reputation. It’s 100 degrees in the shade.

The tour highlights some of the steps Weinkauf and his team of workers took to safeguard the investment made decades ago by Beth Novak Milliken’s father, a doctor who abruptly pulled up stakes in 1972 and moved his wife and five children from San Diego to this plot of land in then rural and remote – and inexpensive – St. Helena.

For Novak Milliken, keeping the family business alive amid the mounting pressures of climate change is a matter of pride.

“My father died in 1977 at age 44, five years after we got here, and it would have been very easy for my mother to give up,” she says. “But with the encouragement and help of others in this community, she made a go of it. So now it’s my turn."

Weinkauf points out how the winery hopes to hedge against the effects of warming temperature. He motions to the long mesh canopies that line the rows of grapes, designed to cut back on the intensity of the sun rays and help the grapes ripen more slowly.

Next, he runs his hand across the grass at the base of the dry, thick vines, the so-called cover crop that helps the soil retain moisture or, in the case of heavy rains, can be cut back to allow better evaporation.

There are a variety of high-tech gauges that dot the vineyards, all related to detecting the percentage of moisture in the air to more efficiently conserve the water that drips on each vine stalk through small emitters.

Lastly, he points out small, recent plantings that could represent the future of Spottswoode, new grape varietals that will be given a chance to react to temperature swings and spikes.

“With what we’ve been seeing, we simply have to have more tools in our toolbox,” Weinkauf says. “We have one crop. The stakes are high.”

And getting higher. Among the various temperature-based charts prepared for Spottswoode is one that looks at growing season days above 98.6 degrees. The projection for 2039 is a potentially devastating 31 days with temperatures at or above 100 degrees.

“To be honest," Weinkauf says, "I’m not sure how you survive something like that."

Follow USA TODAY national correspondent @marcodellacava