Predictable unpredictability

Most food producers intuitively understand that it is these extreme events — and not more general trends averaged over a season — that knock down crop yields. Violent winds, hail storms, flash floods, and heat waves are far more difficult to predict and adapt to than gradual warming or drying trends.

Producers of perennial food crops like grape vines and fruit trees have a peculiar vulnerability to the extreme weather events that may be associated with global weirding. If such an event levels your annual seed crop, you plow it under, and start over the next season. But what do you do when violent storms not only strip the leaves off your trees, but prune back several years’ worth of woody growth of their fruit-bearing branches? And what do you do when 15- to 50-year old trees no longer receive the required threshold of chill hours in the winter to stimulate spring flowering, or exceed their threshold of summer temperatures required to keep sugar content and flavor in balance within their fruits?

The growing concern among horticultural scientists is that global weirding will be radically reshuffling the areas in which once-favored tree varieties can be grown for optimum quality of their fruits, but where and when these shifts will happen remains difficult to predict. Meteorological studies from Oregon and California across the continent to Pennsylvania suggest that climatic uncertainty is likely to cause a turnover in the varieties that can be grown at any particular site. But there are few physiological and genetic studies to suggest just which fruit and nut varieties may have the greatest resilience in the face of rapid change.

Horticulture has remained an art as much as a science. As such, its capacity to guide farmers in their efforts to adapt to climate change has, until recently, been extremely limited. 

Hail storm in ArizonaA hail storm in Tucson, Arizona.Photo: MwaONevertheless, as America’s fruit crops suffered from several weather anomalies during their harvests late this summer, more than two dozen scientists met in Portugal and presented their ideas on how vine growers and orchard keepers can adapt to shifting climates. Many of the International Horticultural Congress attendees were brought together into sessions facilitated by geographer Jones, whose family has roots in the Oregon wine industry. He noted that up until the last decade, warming trends have allowed many regions to produce better wine, but that future climate projections suggest a far more mixed bag.

Many wine- and fruit-growing regions will face earlier onset of the frost-free season, greater summer heat accumulation, later fall frosts, and pole-ward shifts in the optimal production zones for these perennial crops. Within any given region, varieties now grown across inland valleys may need to be transplanted closer toward coastal zones, to higher elevations, or toward the poles.

As Jones has suggested elsewhere, we may be entering an era where much of our current notions about memorable terroir — the taste of place embedded in wines, fresh fruits, or even grass-fed meats — will become geographically scrambled. Within a few more decades, the most intensely flavored maple syrups may come from O
ntario instead of Vermont, and California’s Sonoma County may no longer offer an optimal climate for the expression of the distinctive taste and texture of its Gravenstein apples. Already, maple sap is running three to four weeks earlier in New England than its historic onset, diminishing yields and shifting flavor profiles.

While it is not very likely that many American food producers will adopt terms such as global weirding and climatic destabilization into their daily vocabulary, more and more farmers and ranchers I speak with are groping for ways to deal with all the uncertainty they face for their crops and livestock. Many rural residents are consummate observers of shifting weather patterns on a local or seasonal scale, but a much larger homework assignment is being foisted upon them.

Put simply, the problem is how can they, their seeds, and breeds further adapt to uncertainty itself, rather than to just assuming that their future will surely be hotter and drier. And how will they market the taste of their place, as many locavores now wish them to, when the parameters of that place — the prevailing patterns of weather, soil moisture, and temperature –  are shifting more rapidly than we had ever imagined they could? What will these shifts mean in terms of food security for the rest of us? What are the chances that at least some us might be facing fruitless falls?