This is the Environment Report. I’m Rebecca Williams.
Warmer temperatures and melting snow are less than ideal for winter sports and outdoor festivals. But as Bob Allen reports, the weird weather has northern Michigan fruit growers holding their breath, hoping to avoid disaster:
In his more than 20 years as an agricultural extension agent in the Traverse City area, Duke Elsner says this is the most bizarre winter weather he’s ever seen.
“The ups and downs have just been remarkable. The inability to hang on to a cold period for any length of time has been very strange.”
A gradual drop in temperature at the beginning of winter and holding there below freezing for long periods are the ideal conditions for plant to become frost hardy.
And hardiness is what protects them from getting damaged by cold.
But when temps bounce up into the 40’s and 50’s as they’ve done frequently this winter, some of that hardiness is lost.
“Our trees and vines can take below zero in a normal winter. I sure wouldn’t want to drop below zero at this point in time, I’ll say that.”
That’s fruit grower Jim Nugent. He and a couple of his neighbors are doing the yearly chore of pruning his cherry trees.
(sound of pruning)
With long-handled saws they reach up eight or ten feet to strip away branches and limbs.
Nugent knows his orchard is vulnerable right now because of a loss of winter hardiness. But there’s not a lot he can do about it.
Things could go either way at this point.
A sudden drop to zero would be serious.
But orchards still may slide by unscathed. If temps gradually drop below freezing and stay there, trees will regain some of their hardiness.
“I don’t believe at this point we’ve had any damage.”
Just down the road from Nugent’s orchard, vines are spread on trellises across the slope of a south-facing hill at Black Star Farms.
At this point, a few days of warmer weather is not such a big deal to winemaker Lee Lutes.
He says grape vines are more deeply rooted than cherry trees and able to withstand cold.
Lutes is more concerned about lack of snow cover. Usually at this time of year there’s a foot or two on the ground. And that blanket of snow insulates the tender parts of the vine that are just above the ground.
“We had that nice snow storm here last week and I felt a moment of relief there seeing six inches of snow on the ground. And now it’s gone again. It’s never good to see exposed ground at this time of the year.”
Growers are wondering if these wild fluctuations in weather are just random events or if they might be the new normal.
Jeff Andresen has been looking into that question. He’s the state’s climatologist and a professor of geology at Michigan State.
And he says the dramatic swing from the cold hard winter of last year to nearly the opposite this year is not just a random spike in a long term pattern.
These extreme changes, he says, are a sign of global climate change.
“It’s not just noise. It’s something longer term and it’s related to a more global signal.”
Climate change tosses up another challenge for northern Michigan fruit growers.
Even if they get through this period of lack of snow and warmer weather, spring brings a new risk.
Andresen’s research shows an overall increase in temperatures of two degrees statewide in the last thirty years.
That’s pushing fruit trees to blossom earlier by as much as a week to ten days.
It wouldn’t be so bad if the last date of spring frost also was shifting to keep pace. But it’s not.
That means the buds that produce the fruit are more exposed to the kind of freeze that wiped out the cherry crop in 2002.
But the peninsulas of northwest Michigan are some of the best tree fruit sites in the world. The surrounding waters help to moderate the most extreme winter weather.
Grower Jim Nugent says what these recent changes in climate do is put a premium on the best sites to grow fruit.
“Our better fruit sites up here are still pretty outstanding. Even with the changes I think we’re going to have a fruit industry here for a long time.”
For the Environment Report, I’m Bob Allen.