Climate change’s impact on wine grapes under study

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Capital News Service
LANSING –If you sip your favorite wine and it tastes a bit funny, climate change may be the culprit.
More extreme weather, like unpredictable springs and long summer droughts, is to blame for changes in grape production, said Erwin Elsner a small fruit educator at Michigan State University.
Scientists say extreme weather is one of the consequences of climate change caused by the burning of fossil fuels. What that means to wine production is as yet unclear, and it’s still too early to tell for certain, Elsner said.
“If we could tell our growers that they could expect consistent warming trends, it would be beneficial, but at this point all we have is a more unpredictable climate. Things continue to change and all we can do is help farmers through as it happens,” Elsner said.
But grapes used to make some white wines, such as Rieslings, depend on consistent temperatures of warm days and cool nights. Inconsistent weather brought on by climate change could cause them to be harvested early, which would change their character, he said.

Winter and summer seasons are key to growing grapes.
“When you drink wine, you are looking for specific characteristics,” said Paolo Sabbatini, an MSU associate professor of horticulture. “When you use grapes for making wine, and if they are not ripe, it is not good and the wine is not distinctive.”
Sabbatini said, “Some grape varieties that we are growing are very sensitive, so if winter tends to be very harsh, they tend to die. The second element is the amount of heat that we receive during the season. Some varieties require a lot of heat.
The Great Lakes region has been getting increasingly warmer, and that’s good for grapes, he said.
Elsner said hot summers aren’t a problem because grapes are tolerant of drought. Temperature increases can be beneficial if they don’t exceed 95 degrees, the point that the grapes start shutting down.
However Sabbatini said a warming climate also means warmer springs, causing grapes to grow early and making them vulnerable to frost.
Hot summer droughts followed by freezing winters make it hard for grapes to adjust, according to Timothy Martinson, a senior viticulture Extension associate at Cornell University’s Department of Horticulture.
“At the end of season, grape vines go into a dormant state,” Martinson said. “How deep they go and how able the buds are to withstand the cold is a gradual process that is very sensitive to temperature, so if you have both cold and warm temperatures, the buds will de-acclimate a bit.”
The average first frost date is not changing quite as much, he said. “We’ve had situations where bud bursts will occur early, and you get a spring frost that can kill some of the green tissue, which can destroy the crops.”
The good thing about grapes is that they come out of dormancy slowly, missing frosts that damage spring fruits that grow on trees like apples and cherries, said Nikki Rothwell, the wine grape industry coordinator for the Northwest Michigan Horticulture Research Center in Traverse City.
And Elsner said, “We are all going to learn together,” adding that it’s “going to take many years to even have a clue to what would be a better grape variety to grow in these different conditions.”
Danielle Woodward writes for Great Lakes Echo.

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