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In California’s Napa Valley, cabernet sauvignon is king.

The bold red wine has made the region world famous, with some bottles retailing at hundreds of dollars. But increasingly severe heat waves are taking a toll on the grape variety, especially in late summer during ripening. As temperatures keep rising, the wine industry is slowly confronting a future where Napa may not be the prime cabernet region it once was.

In the face of climate change, wineries around the world are innovating. New technology is being installed to keep the grapes cool during heat spells. A handful of wineries are going a step further. They’re experimenting with new grapes, ripping out high-value cabernet vines to plant varieties from hotter climates.

The goal is to find heat-tolerant grapes that blend well with cabernet, potentially making up for the flavors that cabernet could lack when temperatures get even hotter. While many bottles labeled cabernet are already blended with other grapes in small amounts, winemakers may need more flexibility in the future.

“We know we have to adapt,” says Avery Heelan, a winemaker at Larkmead Vineyards in Calistoga, Calif. “We can’t just pretend that it’s going to go away, because all we see is each year it’s getting more and more extreme.”

Still, blending with other grapes comes with risks. For a U.S. wine to be labeled cabernet, a bottle must contain 75% cabernet grapes or more. Any less, and it’s considered a red blend. Blends typically don’t command the same prices on store shelves as cabernet, especially since consumers are accustomed to picking U.S. wines by the name of the grape. Moving away from cabernet would be a major financial gamble for Napa’s multibillion-dollar wine industry.

“It is a big shift,” says Elisabeth Forrestel, an assistant professor of viticulture and enology at the University of California, Davis. “Without the market changing or demands changing, you can’t convince someone to grow something that doesn’t sell or doesn’t garner the same price.”

University of California, Davis research assistant Jacob Vito crushes cabernet sauvignon grapes from Napa Valley to analyze their chemical compounds. The lab is studying how heat is affecting the grapes.

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Charbono, anyone?

Some grapes growing at Larkmead Vineyards aren’t ones that many American wine drinkers would recognize. Long rows of vines are labeled: touriga nacional, aglianico, charbono and tempranillo.

“There’s not a huge market for a lot of these varieties,” says Heelan, walking among the vines on a hot summer afternoon. “We’re really choosing them not from popularity, but for their qualities.”

Established more than a century ago, the winery is known for its bottles of cabernet sauvignon. These lesser-known grapes were planted only a few years ago, part of a research vineyard that took the place of cabernet vines.

“Which most people would probably think is a little crazy, considering it’s 3 acres of perfect cabernet land,” Heelan says. “But certainly with the climate and how dramatically it’s changed over even the last 10 years, we really have to start adjusting.”

Winemaker Avery Heelan is growing several rare grape varieties at Larkmead Vineyards in Napa Valley, in the hope that they’ll blend well with cabernet grapes as temperatures get hotter.

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The vineyard is already at the hotter northern end of Napa Valley, but the extreme heat in recent years has been a wake-up call. A late-summer heat wave in 2022 hit temperatures just under 120 degrees at the vineyard, she says.

“When it gets that hot, the vines, they’re done,” she says. “They’re going to go dormant, and when that happens, they’re not ripening anymore.”

In extreme heat, cabernet grapes can lose their rich color. They also dehydrate, wrinkling like raisins, which produces wines that are sweeter and more alcoholic. Heelan says the grapes that the vineyard is testing could provide an added boost of color or acidity to cabernet, helping balance out the wine when temperatures take their toll.

The experiment has its cost. In addition to the lost revenue from removing cabernet, grapevines take up to five years to produce their first crop, plus several more years for the wines to ferment. Heelan says only then will they start to see how the new grapes are performing. But the goal is to prepare the winery for the future, knowing that heat will likely get worse.

“Honestly, the more we experiment and learn about how to adapt, I think the wines are just getting better and better,” she says.

In hotter temperatures, cabernet grapes lose their rich red color and produce sweeter, more alcoholic wines.

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Where cabernet is king

Farther south, Shafer Vineyards sits in the heart of Stags Leap, a Napa wine region that’s known for high-end cabernets. Winemaker Elias Fernandez says the grapes benefit from a cool evening breeze that blows in from San Francisco Bay.

This summer, heat has already been a problem. July was the hottest July on record in California. Fernandez points to a grape cluster where small green grapes are nestled among larger purple ones.

“This is effects of the heat,” he says. “It’s not maturing, so this is where you lose some fruit.”

Winemaker Elias Fernandez is installing new technology at Shafer Vineyards in Napa Valley to combat heat waves.

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The damage isn’t too widespread this year, unlike in 2022. But with summers getting more intense, Fernandez says the winery is looking at technology to help the cabernet vines. They’re currently installing misters, which spray water into the air to cool the temperature.

“It’s a constant mist,” he says. “How many of you have been to a party where they have misters? Doesn’t that feel good? Well, that’s what the vines are feeling.”

Still, using extra water is a challenge in drought-prone California, he says. Plus, the water droplets can concentrate the light on the grapes and burn them, so misters must be run until the sun sets to keep the droplets from collecting. But Fernandez says he’s hoping the misting will keep the cabernet vines producing at the highest level.

“I think the first thing we’ll be doing is mitigation, hoping to keep it as the true varietal of Napa Valley,” he says. “That’s what we’re trying to do — is buy time and see what happens with this whole thing.”

For now, he’s not considering planting other grape varieties. With wines that are priced at $100 and up, cabernet is central to their business.

“For me, it’s hard to think that people are just going to throw cabernet out the door and plant something else,” he says. “I really do. It’s the king of the wines of the world.”

To keep producing high-quality cabernets, Napa Valley winemakers may need to blend them with other grapes to balance out the effects of heat. But wines labeled as blends, instead of cabernet, often sell at lower prices.

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Wine regions are shifting

Professor Elisabeth Forrestel is studying how Napa’s wine regions are shifting with climate change.

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Elisabeth Forrestel is one person trying to understand the big swings in the temperature. In her lab at UC Davis, her research team is smashing Napa Valley grapes inside plastic bags. They’ll be analyzed at the molecular level to see how they change during the summer.

Forrestel’s lab is gathering wine grapes from Napa Valley throughout the growing season, along with detailed temperature data, to see how the most crucial compounds for wine are affected by heat. Studies show the average temperature during the last 45 days of the growing season in Napa — when grapes ripen— has already warmed almost 3 degrees Fahrenheit from 1958 to 2016. But it’s the intense heat waves that do the most damage to molecules that produce a wine’s color and aroma.

“When you have these extreme heat events, you can have a lot of impact on the development of that flavor profile,” she says. “If it was just an average change, it would be a lot easier to manage.”

Forrestel is working on updating a central guide for winemaking, known as the Winkler Index. Developed in the 1940s, it shows the ideal locations to grow different varieties of wine grapes, based on how much heat they receive. Napa Valley was originally indexed for cabernet sauvignon, but this could shift as the climate gets hotter.

With cabernet being the world’s most widely grown wine grape, cabernet vines are resilient to different temperatures, Forrestel says. It’s a question of whether Napa winemakers may need new strategies to keep it producing at such a high-quality level. Since grapevines last 50 years or more, winemakers are faced with making planting decisions today that will need to withstand a hotter future.

“Some of the paradigms in what you would plant need to shift,” she says. “People need to have different approaches so there can be more resilience and you can have more options.”

UC Davis research associate Martina Galeano prepares grape samples. Wine grapes need heat for ripening, but too much heat can break down some of the crucial compounds for wine flavor and color.

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Would you pay the same for a blend?

Blending cabernet with other red grapes could be one strategy. But since U.S. regulations require any bottle labeled cabernet to contain 75% cabernet, at some point wineries may be looking at changing their labels to say “red blend.”

“We have a perception that a blend is not as high quality as getting that high-quality cabernet, and they’re not on the same price point, so it is a big shift,” Forrestel says.

The challenge is particular to U.S. winemakers, since many other countries label their wines by region, instead of grape. The famed red wines from Bordeaux in France are already a mix of six grapes, including cabernet, so winemakers have more flexibility. Winemakers there have also struggled with heat, so French authorities recently approved four more red-grape varieties for blending. Since the wines are labeled with Bordeaux, wine drinkers may not even notice the shift.

Wines in the U.S. are generally labeled by the grape variety, a system that was promoted when the domestic wine industry was growing in prominence decades ago. In an effort to compete with wines from Europe, some thought focusing on the grape variety would demystify wines for consumers and show the quality of American wines.

Now, that system may work against them. Cabernet sauvignon is the most popular red wine in the U.S., according to NielsenIQ. So Forrestel says consumers are also part of the solution by creating demand for wines that are better suited for a hotter climate.

“Be open,” she says. “Because I think it’s really easy to walk in and buy what you’re used to. And also, trust what you like and not what you’re told to like.”

On a glorious summer day, a preschooler named Roger teetered on rocks dotting a creek in eastern Orange County, unsure if he could make it back to where his classmates and caregivers were waiting.

A volunteer youth mentor with Earthroots Field School stuck out her hand, reassuring the 3-year-old, who grasped it and took one confident step toward her. Then another. “There we go!” someone called out as he cleared the burbling waterway.

Pushing edges — like learning to balance on rocks without a parent swooping in — is a central tenet of nature-based education, according to Angela Capps, a teacher at the school, one of a rapidly growing number of early education providers that are centered around the natural world.

Youngsters use artificial eggs and natural materials to create nests during forest kindergarten summer camp at Earthroots Field School in Silverado Canyon.

(Allen J. Schaben / Los Angeles Times)

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Nature-based education — sometimes called forest schools, nature preschools or outdoor kindergartens — is based on a straightforward premise: “that it’s really good to have kids outdoors a goodly chunk of their day,” said David Sobel, professor emeritus at Antioch University New England and author of “Beyond Ecophobia: Reclaiming the Heart in Nature Education.”

Indeed, researchers have found nature-based learning supports creativity, resiliency, executive function, school readiness and a host of other benefits for the body and mind.

Scandinavia-originated forest schools arrived in the U.S. in the 1960s and are part of the broader nature-based education movement. In recent years, the concept has exploded amid worries about children getting lost in the virtual world and the country’s youth mental health crisis. The pandemic turbocharged the trend, as schools closed and parents sought safe learning environments for their preschoolers.

As of the last school year, there were about 800 nature preschools in the U.S., a 200% increase since 2017, according to a survey by the nonprofit Natural Start Alliance, which supports access to nature-based early childhood education. California is among the top three states with the highest number of schools, which primarily serve children ages 3 to 5.

Children and parents explore a creek on a temperate summer day during forest kindergarten camp at Big Oak Canyon, a 39-acre property that serves as home base for Earthroots Field School.

(Allen J. Schaben / Los Angeles Times)

Proponents say children immersed in nature are happier and healthier — and may be poised to become the next generation of climate warriors. An early connection to nature can plant the seeds for its stewardship.

“We only protect that which we love,” said Lia Grippo, president of the California Assn. of Forest Schools. “If we want children to grow into adults who can carry the burdens, honestly, we and previous generations have created for them, then they have to be in love with the land they live on.”

While the movement is suffused with optimism — as growth shows no sign of slowing down — there are challenges.

A large number of programs are unlicensed and therefore unable to tap public funding, prompting criticism that they’re only accessible to wealthy families who can pay tuition, and the movement is contending with a stark lack of diversity that hasn’t meaningfully improved even as programs multiplied.

According to Alliance’s recent survey, white children made up 78% of the student bodies of nature preschools, compared with roughly 47% of the U.S population. Latino and Black children are underrepresented relative to the broader population. (Addressing racial disparities is top of mind for many nature educators, and this past year saw the creation of the Black Educator Network, an Alliance-affiliated professional community for Black educators in nature-based early education.)

Many of the programs are geared toward preschoolers, in part because of a desire to front-load a child’s life with meaningful experiences in nature. Another reason is early education tends to be more flexible than grade school in terms of structure and regulation, or as Sobel puts it: It’s “less riddled with academic expectations so it’s a place where the innovation could happen easier.”

Many programs strive to develop environmental literacy, which can broadly be defined as understanding and caring about environmental issues and having the skills needed to work toward solving them. But how do teachers start molding preschoolers into model environmental citizens?

Jodi Levine, executive director of Earthroots Field School, helps a summer camp attendee make a nest.

(Allen J. Schaben / Los Angeles Times)

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Jodi Levine, executive director of Earthroots, said the teachers don’t directly discuss climate change with their very young learners. Creating lessons that help kids “fall in love with nature” is “all that they need to understand the beauty of it and the value so that it’s not destroyed,” she said.

Becca Hackett-Levy, founder and director of Northeast L.A. Forest School, said learning about climate change “can start the day they come out of the womb.” It’s not about discussing the science or overarching concepts, but “about being present in nature and seeing what we as humans are doing.”

Children also experience it firsthand. Last year, a brush fire forced a group to evacuate from Elysian Park. Ash rained down as the children were asked to share what they felt, saw, heard, tasted and smelled. Hackett-Levy said it was a concrete lesson about a warming climate colliding with dry invasive grasses.

Fabienne Hadorn, co-founder of the Arroyo Nature School, which operates outdoors in a public park in Pasadena, said the topic sometimes comes up as children ask questions and make observations. The discussions don’t involve the term “climate change,” but center on the impacts — such as cars causing damage to the air. The emphasis is often on the need to take care of the planet.

Scout, 2, plays in the mud kitchen at Arroyo Nature School. She made several delicious “cakes.”

(Christina House / Los Angeles Times)

Talking about climate change can be stressful, but not all stress is equal, according to Rahil Briggs, national director of Zero to Three’s HealthySteps, a pediatric primary care program. If a child is in a stable, safe and nurturing environment, they can experience “positive stress.” A small amount of motivating anxiety, she said, is helpful for learning new skills. It can be felt while learning to cross a stream or discussing the environment in a developmentally appropriate way.

While California education officials have championed environmental literacy for students, foundational elements of nature school can put it at odds with public education and regulatory norms.

Nature schools, for example, typically embrace managed risk. Many in the movement see exposing kids to experiences such as climbing a tree as key to developing the resiliency needed to withstand future stressors.

Hadorn said her staff may offer guidance as the children climb trees, advising where to put their foot, or catch them if they falter, but the youngsters lead the charge. “We make sure a teacher at every moment is there if they want to climb,” she added.

Children play beneath the trees on a warm summer day at Arroyo Nature School.

(Christina House / Los Angeles Times)

Operating outside can also create tension with public land managers. Levine said she was kicked out of two parks as she learned to navigate the rules — including the requirement that visitors stay on paths. “We know better now,” she said, and students are taught to respect the rules of places they go. (Eventually the school acquired a property in Silverado Canyon.)

Hadorn said she moved locations in Lower Arroyo Park after officials tried to charge her a fee associated with renting out a specific area of the park — a category she doesn’t think applies to her roving band of children. She said she has a good relationship with the rangers and always makes sure the area is left in pristine condition.

Hackett-Levy approached L.A. city park officials and worked out an agreement to hold classes in Elysian and Griffith parks. Previously, she’d sometimes try to nab a first-come, first-served area, but would find herself scrambling if someone else had gotten there first.

According to the survey by Natural Start Alliance, 42% of nature schools are not licensed. The percentage is much smaller for programs that are based entirely outdoors, and, according to state regulators, there are none in California.

Kit Harrington, Alliance’s senior policy advisor, said these schools often operate for fewer hours or with fewer children than required for licensing, or are otherwise exempt. Being unlicensed “could imply that something should be licensed but isn’t (as in an unlicensed doctor, for example),” she said in an email. “In the case of these programs, they are primarily operating in ways that don’t require them to be licensed.”

In many states, fully outdoor schools aren’t eligible for licensing. California regulators indicated it’s a gray area and there does not appear to be an effort to clarify the rules or develop new ones.

Earthroots Field School’s Jodi Levine helps children up a bank after checking out a creek.

(Allen J. Schaben / Los Angeles Times)

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Some nature educators want a path to licensing, but others fear regulations will undercut the spirit of the programs.

Hadorn wonders what might become of tree climbing. Would they set a height limit? She acknowledges that there are upsides, however, such as providing security for parents.

Zoli, 4, plays with yarn and sticks at Arroyo Nature School.

(Christina House / Los Angeles Times)

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There’s also concern that the landscape — the primary classroom for nature schools — is becoming less safe for youngsters. Extreme phenomena are challenging nature schools’ emphasis on withstanding the elements by simply wearing the right gear. California — touted as a great backdrop for outdoor education because of its frequent bluebird days — is experiencing increasingly fierce wildfires and punishing heat.

The elements disproportionately affect young children, whose smaller bodies absorb “more of the bad stuff,” said Briggs, who is also a clinical professor of pediatrics, psychiatry and behavioral sciences at the Albert Einstein College of Medicine in New York.

As the climate and regulatory landscape evolves, nature continues to teach.

On a recent scorching day, the cascading branches of a California peppertree enveloped a dozen children attending Arroyo Nature School. Hours passed without a phone in sight. Leo, Zoli and Francis wrapped yarn around sticks to create a makeshift jail. Desmond worked water into clay. Asa and Mylo read books about bugs and cars.

Scout brought over a fresh-baked cake to sample. The secret ingredient? Mud.

The gloopy stuff clung to the 2-year-old’s arms like organic opera gloves. It threatened to sully her white dress flecked with rainbows.

She didn’t mind.