To the litany of changes being wrought by global warming, we may be able to add one more: where wine grapes can and can’t be grown.

Within 30 years, the areas where California can grow fine-wine grapes could shrink because of climate change, while little-known growing regions such as Seattle’s Puget Sound and Oregon’s Willamette Valley see growth, according to one controversial study.

A federal agency report in 2009 found that average U.S. temperatures could increase 2 to 4 degrees by 2020 compared with the 1970s’ average. That’s not huge, but the best grapes “grow in a narrow geographic range that exhibits a narrow climate envelope,” says Noah Diffenbaugh, a climate scientist at Stanford University.