Tornado clouds over farmhousePhoto: Stuck in CustomsThe Driftless region in southwestern Wisconsin is renowned for its apples, with their intense flavors favored in marketplaces as far away as Detroit. But when I arrived there in late September to search with friends for heirloom apple varieties, we had trouble finding any apples left on the trees at all.

“This has been the strangest year for apple growing within my memory,” orchardist Dan Bussey conceded. The apple crop ripened nearly two weeks ahead of time, and due to a late frost, several late-season windstorms and most orchards, the crop in southern Wisconsin was quite sparse, he said. “Most orchards I know ran low or even out of apples by early October,” he wrote to me a few weeks later.

Bussey and his family have been using the same cider press in their community of Edgerton, Wis., for decades; ever since he purchased it in 1989, he has pressed cider for as many as 16 neighboring apple orchards during the harvest season. This year he’s run the press weekly, but for only a small fraction of what he normally does.

No wonder. Wisconsin not only had the wettest summer on record, but growers in the state have already suffered 40 tornadoes in 2010 — twice the average annual number that have been experienced since detailed records began to be taken.

All hail Nature

When I returned home from Wisconsin to the grape-growing region of southeastern Arizona, I sat in on a meeting between wine makers and congressional legislative aides hoping to assist them with disaster relief. A mid-August hail storm wreaked a half-million dollars of damage to grape-laden vines in less than two hours, resulting in a projected loss of more than $2 million of income among 10 of the area’s vintners. My neighbor Kent Callaghan of Callaghan Vineyards in Elgin, Ariz., called the damage “unprecedented,” but nevertheless reminded me that the August tempest was not the first hail storm that had hit his vines.

“We’ve had nine hail storms in the last six years. But get this — in the previous 19 years, we didn’t have a single one … Go figure that one out for me!”

Not long after that last hail storm, I called up another neighbor of ours, Mark Douglas, who has tenaciously maintained a mixed orchard of dozens of varieties of fruits and nuts for more than a quarter-century. The hail had defoliated most of his fruit and nut trees. Then, in late August and September, many of them broke into bloom, months after their normal season of blossoms!

The weather anomalies that North American farmers and orchard keepers have experienced over this past growing season may be part of what journalist Thomas Friedman has dubbed global weirding, a far better catch-all term than global warming.

Major fruit-growing states such as Virginia and North Carolina did indeed experience their warmest summer on record, while many other states had subnormal temperatures. Wine regions on the West Coast experienced the latest, coolest, and most peculiar vintage in nearly 50 years, but vintners near the East Coast — from the Finger Lakes to Niagara — had one of their earliest and best vintages on record.

The hallmark of global weirding is increasing extremes in variability, which scientists evaluate with a metric called “the coefficient of variation.” Wine geographer Greg Jones has observed that week to week, variability in temperatures in wine regions globally has increased. “The coefficient of variation over vintages has gone up in nearly every wine region I have analyzed. There’s much greater variability around the mean than at any other time in the past data record.”

There’s another measure of climatic instability that’s far more telling for the North American continent as a whole. The Climate Extremes Index (CEI) integrates the occurrences of several types of extreme weather, such as dry spells, torrential rains, and unusually warm nighttime temperatures. The National Climatic Data Center recorded that for the summer of 2010, the CEI was roughly 1.5 times its historic average.