Weather Watch
Agriculture savant Frederick Kirschenmann assesses the potential effects of climate change on farming in the United States and ways to ensure adequate food supplies in the future.
| More Food Faces Change in this issue |
| The Price Is Fright Is America's reliance on cheap food over? Looks that way, as an onrush of complex factors unloose a perfect storm of spiraling costs. Agriculture policy and World Bank veteran August Schumacher Jr., recipient of this month's Silver Spoon Award, scrutinizes the spinning weather vane with an eye to the future. |
| The Price of Purity Convinced that an ever greening public is willing to pay a little more, a young Argentine restaurateur is determined to take his organic concept national. |
| Seed Capital Heirloom tomatoes are much more than a menu item du jour or a glorious still life at the local farmers' market. They are part and parcel of preserving our agricultural heritage. Katy Keiffer reviews the definitive new book on the subject. |
| Awake at the Switch At a conference in Spain assessing the effects of global warming on wine production, Alan Tardi discovers that what's bad news for some is good news for others. |
| In for the Short Haul Careening fuel costs and demand for eco-friendly product are causing sharp swerves on the food distribution highway. Katy Keiffer spots some green lights at the end of long-distance tunnels. |
| Staving Off Extinction Biodiversity is more than a catchword, a liberal conceit, or a sentimental love of nature. It's a matter of live and death. Pulitzer Prize winning science editor Holcomb B. Noble reviews the new definitive work on the subject. |
| Plowing Toward Utopia Christopher Styler reports on the efforts to transform the American farm into a model of environmental enlightenment, community good, impeccable ethics, and, yes, gainful employment. |
| Massing Links Judith Weinraub speaks with environmentalist and social activist Paul Hawken about offtrack food practices and policies and what can be done to reverse them. |
| Silver Spoon August Schumacher Jr. |
While climatologists are in general agreement that rising concentrations of greenhouse gases in the atmosphere will have significant impacts on agriculture, they are reluctant to make specific predictions for any region of the planet. The difficulty in making very precise predictions lies in the fact that the effects of temperature changes will be determined by a complex set of factors affecting productivity in interactive ways.
It's generally recognized, for example, that increase in carbon dioxide may increase CO2 fertilization, which could increase crop yields by as much as 15 percent or more. Increases in temperature may produce longer growing seasons in certain regions as well as increased precipitation—all of which could increase productivity. At the same time, increases in temperature will likely cause more unstable climates, including more droughts and more floods, which in turn could cause more heat stress, more pests, and increase salinization, desertification, and soil erosion—all of which are likely to decrease productive capacity.
Other interactive factors may come into play. Increases in global temperature may significantly reduce snowpack, which is the prime source of irrigation water in some regions. Some computer modeling studies have suggested that rainfall may increase by as much as 20 percent in some regions. However, that increased rainfall will come in the form of more violent storms, thereby increasing the amount of surface runoff by as much as 50 percent. That would significantly increase soil erosion, especially in regions where extensive row crop monocultures are practiced. Such conditions are also likely to increase crop losses due to soil waterlogging.
Climate change could also have a significant impact on the biological diversity which supports agriculture. Many species of plants and animals can only thrive in specific thermo climes and are not capable of migrating as quickly as temperatures change and so will likely become extinct. In most cases such species are part of a complex interdependent biological community that we don't even understand so there's no way of knowing in advance what effect the disappearance of one species may have on the agroecosystem of the region. In many instances this biological diversity is essential to agricultural productivity.
The potential loss of climate stability may be especially devastating to productivity given our highly specialized industrial production systems. In Iowa, for example, 92 percent of cultivated land is in just two crops—corn and soybeans. Consequently stable climates, consistently favorable to corn and soybeans, are essential to maintaining productivity in Iowa. Areas dominated by flowering crops may be devastated by unusually warm periods in early spring that cause premature flowering, followed by late frosts, which can drastically reduce yields. In southern wheat growing areas, yields could be affected by lack of cold hardening followed by late cold snaps, increasing winter kill.
A further potential loss of productivity related to climate instability can be expected due to depleting fresh water resources for irrigation. Greater drought frequencies will likely increase the demand for irrigation at a time when global fresh water resources are being depleted at an unsustainable rate. In China, where 80 percent of grain production is dependent on irrigation, groundwater is being drawn down at the rate of 10 feet per year. In the United States central plains, where most irrigation water is derived from the Ogallala aquifer, that water source has already been depleted by half, making even current rates of depletion unsustainable.
In addition to the potential effects that climate change due to greenhouse gases may have on agricultural productivity, it's important to also keep in mind that the stable climates of the past century may not be the norm. In 1975 the National Academy of Sciences' Climate Panel reminded us that the unusual agricultural productivity that we enjoyed during the 20th century was at least due as much to "abnormal" stable climates as to the new technologies we developed. As such climate stability is not the norm, and since climate instability may be further increased due to human activity, the panel recommended that we develop a food system that can sustain productivity under much more unstable climate conditions.
Of course, new technologies may lead to greater productivity, but it's unlikely that the increases due to technological development will exceed the demand generated by the increase in population, consumption, and the need for agricultural production of biomass (corn, switchgrass, crop residues, etc.) for alternative energy.
Given these realities, it seems prudent to pursue two courses of action to ensure an adequate food supply. First, we should embark on a global soil restoration program. Extensive research has demonstrated that improving the biological health and organic matter of the soil can dramatically improve soil moisture efficiency owing to the soil's increased capacity for water absorption and retention. Biologically active soils can also reduce the need for fertilizers and other energy inputs. Second, we should explore more biologically diverse farming systems, which tend to be more resilient under unstable climate conditions and which have the potential to produce multiple food products on limited acreage at reduced energy inputs by virtue of biological synergies in which the waste of one species becomes the food for another. Such energy exchange systems mimic nature, which has a demonstrated record of resilience in the face of extreme events.
