The Montmorency tart cherry is pretty much the only sour cherry grown in the U.S. And cherry growers in Michigan know the tree really well. It was brought here from France a couple hundred years ago. "This is older than most people think of as heirloom varieties and it's our main variety to this day," says Jim Nugent, a cherry grower in northern Michigan.

The tree is "very cold hardy" in the dead of winter, he says, and grows well in the state. But it is susceptible to damage from spring frost, making it very sensitive to the extreme weather shifts made more likely by climate change. And that made tart cherry growers nervous.

Warmer days in early spring have caused cherry buds to come out earlier on average. That combined with erratic spring weather, especially when it brings severe cold snaps, has already proved disastrous for the crop.

In 2002 and 2012 freezing spring temperatures wiped out almost the entire tart cherry crop here. Nugent jokes that he couldn't harvest enough cherries to make a pie. In other years, the yields have varied widely.

The hot spell in February this year alarmed cherry growers, but the trees are OK for now. However, Jim Nugent hasn't done anything to protect his orchards from the next severe cold snap. There is little he can do, in the short run.

About 30 miles from Nugent's orchard, Todd Springer, another grower, is trying to deal with a different problem related to climate change – poor pollination. He says the honey bees that usually pollinate his fruit don't like the erratic spring weather. If there's a strong wind or if it's rainy or cold, honey bees stay in the hive.

So, he is out in his orchard, hanging a homemade beehive for a kind of bee called horn-faced. The hive is made of a white bucket with brown cardboard tubes stacked inside. The bees hang out inside the tubes. These horn-faced bees will work in inclement weather to pollinate the cherry trees, even at night. Springer calls these bees his "pollinator insurance."

Springer wants to make sure his family can keep farming land they have been on since 1868. "If we don't grow cherries," he says, "we don't get to keep our farm."

Despite all these difficulties, Springer says it's been hard for cherry growers to talk openly about climate change. Everyone has so much at stake, he says. "It means we have to change," he says. "And does that change look like?"

He was at a conference once with a speaker talking about warming temperatures when a grower got angry and yelled, and claimed that this information was presented to cost farmers more money.

Last month, Springer signed up for an all-day workshop, but it was cancelled due to lack of interest. He says it's ironic that one of the talks was about whether the public cares about the problems climate change might cause farmers. "And we couldn't get more than 11 farmers to come to the meeting, to care about it," he says. "I don't know what that says, but like I said, it's hard to talk about, it's hard to listen to."

It turns out that the public does care about how climate change affects farmers, at least, in Michigan, says Julie Winkler, a geology professor at Michigan State University, who was supposed to share her research at that workshop.

Winkler was involved in a survey that found that people do want the government to help farmers adapt to climate change, especially when asked during record hot weather. "It was up to 80 percent but it fell back to about 70 percent after the warm spell, so it actually was quite strong," she says.

If there was money to help cherry farmers adapt, it's not clear yet, how it would best be spent. Many have fans blowing cold air out of valleys where it settles. Some growers are experimenting with sprinklers to cool trees and keep them dormant a little longer in the spring.

Jim Nugent thinks what's really needed is a new breed of tart cherry that's less susceptible to frost. "I'm not sure if 50 years from now if Montmorency is still going to be a viable variety," he says. "I think we've got to find something that is going to be more frost-tolerant."

Researchers are trying to breed trees that bloom later, but introducing a new breed to the market can take decades. And Jim Nugent says researchers have only been at it since the 1980s.

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