There’s just something about cherries. They’re small, sweet and crunchy, with an early harvest that tells us summer’s coming. Right now, though, this beloved fruit is a bit of a canary in a coal mine. The last couple of cherry harvests could be a warning about climate change and its impact on future tree crops.

To find out more, I went to the south end of the Santa Clara Valley to meet Nicole Rajkovich. She started working with her family at Fairhaven Orchards when she was a little kid.

“That was my fun summer vacation,” she says. “I didn’t go to the beach. I didn’t go on family vacation. We were working in the fruit stand every summer, and it was just so much fun.”

So when the weather got weird this winter, she was nervous. Up near Yreka, people got flooded out. At Huntington Beach, it hailed. In San Francisco, where I was walking around in a sundress, meteorologists announced it was the driest January ever. Rajkovich distinctly remembers the 90-degree heat.

“That’s great for sunbathing, but it’s not optimal weather for our crops,” she says.

I meet up with her at one plot a couple of hours south of San Francisco, in the shadow of big box stores in Gilroy. The four men on the crew use ladders to reach all the deep-red Royal Hazel cherries, dropping them into buckets slung around their necks then loading them into bins on a truck. Rajkovitch says this is one of only a handful of orchards they can harvest this year.

“It seems like the past couple years the warmer winters made us have huge failures in our crops,” she says.

She’s not talking about the drought, though that certainly doesn’t help. They’re not getting any water from their former source, the Central Valley Water Project, but their wells are holding up okay. What really hurts the cherry trees is that winter temperatures here weren’t cold enough for long enough.

“If they don’t get enough chill hours they don’t produce the fruit,” she says.

Put simply: Chill hours are crucial blocks of time when temperatures drop below 45 degrees. To produce a robust crop, fruit and nut trees need a certain amount of chilling for a healthy dormancy period. Cherries are really sensitive, needing more chill hours than most tree crops.

Case in point: the cherries in the Rajkovich home orchard in nearby Hollister. Here, the classic Bing cherry trees look confused about what season it is, what they’re supposed to be doing. I meet up with Bill Coates, a longtime farm adviser here in San Benito County, to learn more.

“You have some ripe cherries, you have some blossoms, some branches that are almost devoid of leaves, and you have some buds that are still dormant,” he explains. “And this is all a result of lack of chilling.”

Bing cherries need about 1,000 hours, but San Benito County got just over 500. Chill hours are down all over the state. In California, the USDA reports last year’s cherry production down 60 percent. And scientists at UC Davis predict that if greenhouse gas emissions aren’t curbed, chill hours will continue to shrink.

“People may disagree on the cause of the change,” Coates says, “but there definitely has been a change in the climate, and it’s going to impact tree crops greatly.”

He would love to see more effort put into breeding varieties that can withstand less chilling. Cherries won’t make or break California’s agricultural economy on their own, but the way they’re hit by fewer chill hours may serve as a warning for more lucrative commodities that are slightly less sensitive, tree crops like apples, pears and walnuts.

A few feet away from the orchard, Nicole’s father, George Rajkovich, maneuvers a forklift, loading pallets of cherries onto a customer’s truck. This fruit all comes from those few orchards in production in Gilroy.

“This year, there’s nothing out there in our Hollister orchards ...  nothing,” Rajkovich says.

Of the few cherries that did grow, many were damaged by rain in May. He thinks they’ll get 5 percent of a normal harvest in Hollister.

“In my lifetime, I’ve never seen one so bad,” he says.

And Rajkovich has seen a lot of cherry harvests. His father planted in San Jose after he emigrated from a region of the Austro-Hungarian Empire, before it became Yugoslavia, before it became Croatia. He and his brother would go running through the orchards, chasing their father and uncle, waiting for their mother to bring them lunch.

“I knew nothing else,” he says.

He and his brother farmed all over this region, and they started planting cherries in Hollister in the late '50s, and started a fruit stand in the '70s. Rajkovich remembers decades ago when they’d have to put smudge pots in the orchards in the middle of the night and turn on fans to keep frost from killing a crop. He says he hasn’t had to do that in 20 years.

When his brother died eight years ago, Rajkovich had a talk with his kids.

“It’s up to you now,” he recalls, choking up. ‘We’ll sell it, or take it over.”

They did. The kids joined their parents and continue to look for ways to lessen climate change’s negative impact: planting sod between rows of trees to keep moisture in the ground, experimenting with different cherry varieties, and using technology to figure out exactly when to apply chemicals that can help trees produce despite reduced chilling. Why all the effort? Because unlike lettuce or strawberries, for instance, trees have to be planned sometimes decades ahead.

“We have a whole lifetime actually of work and expense in planting and nurturing these orchards,” Rajkovich says. “If we don’t get chilling and don’t get production we have to start changing crops.”

They’re already doing that. On new land they’ve bought, and orchards they’ve had to pull, the Rajkovich’s planted walnut trees, not cherries.

This piece is part of the series California Foodways. Stories in the series about food and climate change are funded by a grant from Invoking the Pause. Lisa Morehouse produced this story while at a residency at the Mesa Refuge.