By Bob Allen
Temperatures across the Great Lakes region are breaking records for the month of March. Climate researchers say there's never been anything like it going back more than a hundred years. And for fruit growers, the likelihood of escaping without major damage doesn't look good.
The warmest March on record in Michigan is 1945. And Jeff Andresen says what we're seeing today blows that away with some to spare. "We're seeing history made before our eyes at least in terms of climatology."
Andresen is the state's climatologist and professor of geography at Michigan State. He says it looks like the average temperature this month also will exceed the normal high in April as well. "And in some ways if we look at where our vegetation is and how advanced it is, it's probably a month ahead of where it typically is," Andresen says.
Andresen is careful to point out that this year's early warm-up is an extreme weather event. It's not a direct result of climate change. But it fits a predicted long term pattern of change that includes such extreme fluctuations.
In Northwest Michigan, if warmer temps hold up, cherry trees could start blooming next week instead of in early May. And that extends the risk for frost damage.
But Nikki Rothwell says there are other concerns besides a freeze. "There's going to be a challenge to fight off more insects, more generations of insects and a longer season of fighting those pathogens." Growers already have started spraying for fungus that usually is kept under wraps in the soil until the snow melts.
Rothwell is director of the Northwest Michigan Horticultural Research Center in Leelanau County. She's been checking the cherry trees in their experimental orchards. "It's just been uncanny," she says. "When I go out and look at those trees I look at what we saw yesterday in development and then I look at what we saw today in development and it actually looks like it kind of jumped to the next stage of development."
Normally, that kind of growth would take weeks to occur. But, as Rothwell says, she's not sure what's normal anymore.
Crop Damage Likely
Research shows a trend over the last thirty years of earlier spring warm-ups by as much as seven to ten days, on average. But the last date for a killing freeze has not moved earlier to keep pace.
Jeff Andresen has checked climate data going back more than a hundred years. And he says, despite the warming trend, the chances of skating by entirely without a killing freeze at this point are not good.
"There has never been a spring season, April, May or June, in which we have not observed freezing temperatures, or actually hard freezes. We looked at both thirty-two and twenty-eight degree thresholds, it's never happened," Andresen says.
Researchers calculate that if the temperature drops to twenty-nine or lower over the next six weeks or so there will be major damage to fruit crops.