David Wolfe: The Week In Weather

Fewer Fruit and Nut Trees In A Warmer World People who live around orchards are well aware of the cycles of fruit trees – with hillsides turning white with apple blossoms in spring, and fruit ripening through the summer and fall. But few realize how key winter's chill is to that cycle''s success. As the climate warms, this fact will become more and more apparent, as fruit yields drop and entire regions lose once-successful orchards, according to one of the nation''s foremost experts on climate''s affect on agriculture, David W. Wolfe. Wolfe, a professor of plant ecology at Cornell University in New York, talked with The Daily Green''s news editor, Dan Shapley. This is the second part of a five-part interview, to be published on Fridays in May and June. Last week, we learned that warmer winters in the Northeast have favored European wine grape varietals because the vines have thrived in the absence of deep winter freezes. “For apples,” Wolfe said, “it''s just the opposite going on.” Apple and other fruit and nut trees need specific “winter chilling hours” to thrive. Many require as many as 1,800 hours below about 45 degrees to produce strong crops. As winters continue to warm – about 4.4 degrees on average in the past 30 years – having enough cold days per winter could become tough in important fruit- and nut-growing regions in New York, California and elsewhere, Wolfe said. Apples, plums, peaches, almonds and other crops will feel the pinch. Another danger is that trees can bloom during once-rare mid-winter thaws. Subsequent freezes can damage leaves and blooms, damaging yields. “In the last 30 years we''ve seen a level of climate change that is enough to really affect our agricultural industries, but it''s just the beginning,” Wolfe said. “I think it''s getting very close to the point where the shrewd grower might be keeping a real close eye on this, and starting some experiments on a small scale (with varieties that thrive in warmer climates).” This is the second part of a five-part interview with David W. Wolfe, one of four scientists coordinating research into climate-related changes to agriculture as part of the U.S. Global Change Research Program. He is a professor of plant ecology at Cornell University in New York. More Week In Weather Posts Maple Syrup And Fall Foliage At Risk From Climate Change - June 1 David Wolfe: Fewer Fruit And Nut Trees In A Warmer World - May 25 David Wolfe: European Wine Grapes Get Unlikely Boost - May 18 Gavin Schmidt: Wildfires Linked To Global Warming - May 11