CONCORD, N.H. — Chuck and Diane Southers' thermal alarm went off around 10:30 p.m. on a fateful night in mid-May.
The alarm takes the temperature out in their 30-acre orchard and blares loudly if it dips too low. That Thursday night in Concord, New Hampshire, it was about 35 degrees Fahrenheit. The temperature kept getting colder.
The Southers' apple orchard was in full bloom, which is normal for mid-May. This year's was particularly good.
"We called it a popcorn bloom," Diane Souther said. "The tree was just white with flowers."
By Friday morning, all the petals were turning brown. The Southers cut open baby apples, about the size of a pencil eraser. Their sap had frozen, expanded, and, in the process, the cells and seeds were destroyed.
"No seeds, no apples," Chuck Souther said, standing between rows of leafy green trees. The Southers first planted their apple orchard in 1978, right after they bought a neglected piece of land in New Hampshire's capital city. They planted their first trees even before they built their home. This year, branches reach into the air unburdened by fruit.
Apple picking at places like the Southers' farm, called Apple Hill, is one of the quintessential New England fall traditions. But a good harvest depends on things that happened months before. This year, many of New Hampshire's trees have no fruit because of that freezing night in May.
Seasonal changes
Fruit growers like the Southers are watching human-caused climate change shift the seasonal patterns they've counted on for years to produce fruit. As the atmosphere warms and weather becomes more unpredictable, some farmers are considering big changes, like planting different crops or finding new ways to protect trees from the elements.
In New Hampshire, farms at higher elevations fared better than lower elevation farms like the Southers. The director of the state's Farm Services Agency, Jeffery Holmes, said this year was unprecedented. Hundreds of acres of crops froze during two big cold snaps: first peaches in February, and then apples in May.
Chuck Souther said he sees weather conditions changing for his farm and others. He's hesitant to talk about the causes, like climate change, but he said the seasons are less predictable than they used to be.
"You don't have to be a scientist to figure out things are different right now," he said.
Jason Londo, a professor of horticulture at Cornell University, agrees. Things are different.
"We are changing the stability of all of our seasons," he said.
Londo studies how fruit crops are adapting to human-driven climate change. He said not every damaging event – like that May freeze – indicates a changing climate. The temperatures apple trees have adapted to over thousands of years are shifting as people continue to burn fossil fuels which cause global warming.
Fruit needs a certain number of hours each winter to stay cold and dormant. Then, when it gets warm outside, trees wake up and get ready to bloom. Fall, winter, and spring are all getting warmer.
"Climate change is impacting how our fruit crops perceive the safest time to wake up in the spring," Londo said. "As they wake up earlier and earlier, but the threat of an acute cold event doesn't decrease, they become more and more exposed to these sorts of events."
There's also growing research on how climate change may be making cold snaps more unpredictable.
Farmers across the country are dealing with these changes. This year in Georgia, January and February were super warm – near the top of historical records. Peaches bloomed early. Then in March, two frosts killed almost all of the commercial peaches in the state. In Virginia, freezing days in March and April hurt apples that bloomed early, too.
Fruit growers look for solutions
Growers and scientists are trying a few different things to adapt as climate change continues to pose a threat to future crops, said Pam Knox, an agricultural climatologist with the University of Georgia.
"One is to try different varieties of the same crop that they've been growing," Knox said. "So you might grow an apple that has fewer chill hours than the previous apple you were growing."
In Washington state, scientists have developed a spray made out of cellulose from wood pulp to help insulate fruit. In Georgia, some farmers are growing citrus, or olives, Knox said.
In New Hampshire this fall, the Southers are relying on sales from their farm stand, offering goods like zucchini bread, homemade jelly, and this year, apples they've bought from other farms. They're also focusing on the other fruits and vegetables they grow – raspberries and blueberries did pretty well this year. And they're booking events on their land, like cider tastings.
But looking to the future, Chuck said he and Diane are thinking about backup plans.
"It'd be really nice if we could just say, 'Oh, this is going to be the one we're going to talk about and our grandkids are going to talk about, you know, remember 2023?' But we don't know that," he said.
For now, Chuck said he's optimistic about next year's apples, but the next farmers at Apple Hill could be growing different crops.
