In the orchards of California's Central Valley, global warming has begun to make a difference. To the practiced eye of grower Russ Lester, it's evident in the aborted buds on branches of his walnut trees, more than in years past. Instead, they go on trends and new research from U.C. Davis indicates dramatic climate changes.
"We feel it is a crisis," says U.C. Davis ecologist Dr. Minghua Zhang, Ph.D.
Zhang has co-authored a study of warming trends in the Central Valley. They have maps that predict wintertime temperature increases of five degrees by the end of this century, which is a direct threat to California's $10 billion fruit and nut crop.
The problem is that as winter temperatures rise, trees are less likely to go dormant, which is when they rest. If they don't go dormant, they do not produce.
"Eighty percent of what we grow now will not be available or suitable for the tree crop varieties, today," says Zhang.
Already, growers have noted a decline in production.
"It seems like it's happening a lot more now. There are a lot more erratic temperature changes in the wintertime and so trees don't know how to handle that. They simply get confused," says Lester.
Long term, this research indicates a shift in crop growing patterns, with everything moving north. That's frightening news for a man with 450 acres of walnut trees.
"If we have to replace every tree, then basically, I go broke," says Lester.
Especially if he has to replant with something else. And as one man might go, a statewide industry could follow.