By Robbin S. Johnson
As Congress wrestles with a climate change bill, one may be tempted to ask: What do agriculture and climate change have in common? A lot, it turns out. A changing climate will shift agricultural production patterns while challenging agribusiness and farmers to adapt to these temperature and rainfall shifts. Agriculture, in turn, is a source of greenhouse gases (GHGs) thought to contribute to climate change. And, agriculture can potentially play roles in mitigation and adaptation strategies.
Climate Change's Agricultural Effects
The effects of a changing climate on agriculture are matters of degree and pace. Moderate temperature increases should be beneficial for crops, especially in northern temperate-zone latitudes. Such warming also can increase evaporation and precipitation, reminding us that "rain makes grain."
But not all regions are likely to receive beneficial temperature and rainfall changes. Sub-tropical and semi-arid zones could be hurt even by moderate shifts, and large changes in temperatures spell significant problems for most agricultural areas.
In addition to issues of degree are concerns about the pace of change. Abrupt changes in temperature or rainfall can be disruptive and overpower attempts to adjust through technology, cropping patterns or resource management.
Because of farming's sensitivity to these issues of degree and pace of climate change, agriculturalists are particularly frustrated by the limits that currently exist in forecasting likely climate changes. People who work the soil also must be exasperated by arguments on both sides of the climate-change debate who try to make long-term climate-change claims on the basis of short-term, familiar weather cycles.
Agriculture as a Source of Greenhouse Gases
While controversy surrounds the role of GHGs in climate change, agriculture's role in GHG emissions is becoming clearer. Estimates of agriculture-related emissions range upward from one-sixth to as much as one-third of all GHG emissions. Those caused directly by production agriculture--nitrous oxide from fertilizers, methane from animals and rice paddies and carbon from machinery or released by tillage and decaying organic matter--place agriculture's role at the lower end of that scale.
The effects of agricultural expansion, however, push related GHG emissions upward. Among those causes are de-forestation, conversion of pasture and grasslands to cropping and burning of cover to facilitate land clearing or crop harvesting. Increasing concern also focuses on agriculture's thirst. By using as much as 70 to 90 percent of a region's fresh water supplies, agriculture becomes the major consumer of a commodity that climate change will make increasingly scarce in many regions.
Given these many roles, it may seem odd that the House-passed "American Clean Energy and Security Act of 2009" exempts production agriculture from emission caps imposed on other industries, including the food industry. The so-called Waxman-Peterson agreement also opens the door for farmers to earn "carbon credits" for reducing their GHG emissions--standing the old "polluter pays" principle on its head.
Mitigation and Adaptation Strategies
Whether the United States passes new climate-change legislation or backs into controls through Environmental Protection Agency regulation of carbon emissions is still uncertain, as are prospects for a global successor to the Kyoto Agreement coming out of this fall's negotiations in Copenhagen. But there is much to be done--and being done--through private action.
No- and minimum-tillage systems improve carbon sequestration in the soil. The spread of "precision farming"--use of detailed field-testing and records, global positioning technology and computer-controlled variable-rate application of inputs--will enhance productivity while reducing environmental harms of all sorts. Seed breeding and biotechnology promise crops that increase productivity while becoming more resilient to changing temperature, moisture or pest conditions brought on locally by climate change, while animal breeding and feeding improvements will accelerate weight gain while reducing waste.
Post-production agriculture also has much to contribute. Expanding and liberalizing agricultural trade will ensure reliable supplies to regions where crop prospects dim out of shipments from more favored regions. Greater efficiencies in packaging, transporting and distributing foodstuffs will lighten the industry's overall carbon footprint.
Beyond agriculture, the unprecedented rate of urbanization occurring in the developing world will prove to be a significant adaptation step for mankind as a whole by reducing the number of people whose livelihoods are directly affected by climate. As well, progress in reducing particulate pollution in those countries improves air quality and human health while also slowing the melting of glaciers where such black soot is deposited.
All of this means that agriculture and climate change will remain joined at the hip. New problems no doubt will arise but so will new opportunities and solutions.