Putting politics and blame aside, global warming is occurring and carbon dioxide concentrations in the world are increasing, says a Washington State University researcher. But how does a grower make sense of all the varying predictions?
There are no clear-cut answers or strategies for growers about climate change.
Computerized models used by scientists to forecast changes from global warming are imperfect, said Dr. Mercy Olmstead, WSU Extension viticulture specialist. Olmstead is part of a WSU team that is assisting the University of Washington to better understand the impact of global warming on high-value, specialty crops.
"We’re being asked to predict the future," she said to grape growers and winemakers attending the Washington State Grape Society annual meeting held last November. Several studies about future wine production in the world and the Pacific Northwest have stirred up controversy, she added. "But we’re doing the best we can to show what can happen."
The list of possible changes that grape growers might encounter under a warmer climate is speculative, Olmstead said, emphasizing that they are things that might happen if humans don’t change their ways.
Regions of grape production will likely shift in response to changing temperatures. Europeans are now beginning to plant wine grape varieties in areas that were once considered unsuitable.
One of the more controversial climate models predicts that grape production in the coming century could shift to western Washington
and Oregon, parts of Idaho, Montana, and Colorado, and the New England states. "And in fact, California is almost ‘not’ in terms of grape production," Olmstead said in discussing the model.
The Pacific Northwest will likely benefit most in the cooler areas from climate change, she observed. Cool-climate grape varieties will shift further north, and current warm areas may be able to ripen different warm climate varieties. More consistent ripening could also be a benefit in marginal areas of grape production.
"These changes will probably not affect us, but affect our children and grandchildren," said Olmstead, who is stationed at WSU’s Prosser research center.
She highlighted one change—a rise in the annual minimum average temperature—that is already occurring in Washington State. While maximum annual temperatures in Washington have stayed relatively stable, according to WSU records dating back to 1924, she said the the minimum annual temperature is increasing (see WSU temperature chart).
"This has implications for winter temperatures and implications for acid retention in our grape varieties," Olmstead said. "It’s