As discussions continue on what a cost-effective, comprehensive domestic climate policy might look like in the United States, one of the many critical and unanswered questions is which sectors should be covered. While perhaps most policy attention surrounds the energy and transportation sectors, agriculture is frequently discussed in the context of climate change: not only is agriculture vulnerable to climate change, it is also part of the problem and its potential solutions.
Agriculture is one of the key sectors of the economy that may be strongly affected by climate change, particularly at the regional level. Studies indicate that warming is likely to increase production in areas like the Great Lakes region that are currently constrained by temperature, while changes in rainfall and temperature may significantly hamper production in the South and the Great Plains. Irrigation-dependent agriculture in western states, especially California, may face difficulties with the anticipated reduction of snow pack, which currently helps store winter precipitation for the upcoming growing season. Extreme weather events and changes in pest populations, plant diseases, and other risks are difficult to predict and may further challenge U.S. farmers.
But as climate change affects agriculture, so too does agriculture affect climate. While relatively unimportant for carbon dioxide (CO2) emissions, the agricultural sector is a major source of methane and nitrous oxide, two other major anthropogenic greenhouse gases (GHG). Compared with CO2, methane has considerably greater warming potential but a shorter atmospheric lifetime. Overall, methane is 21 times as potent as CO2 over a 100-year horizon. Nitrous oxide, on the other hand, is characterized by a relatively low warming effect but a very long atmospherice lifetime. This causes nitrous oxide to have a global warming potential 310 times that of CO2. In 2006, CO2, methane, and nitrous oxide constituted about 84.8, 7.9, and 5.2 percent of all U.S. GHG emissions, respectively.
Agricultural practices and products also provide opportunities to mitigate climate change. For example, soil-based carbon sequestration is a potentially inexpensive mitigation option. And as a recent flurry of news stories can attest, the recent biofuels boom, and corn-based ethanol in particular, is transforming U.S. agriculture in ways that have implications not only for GHG emissions and energy production, but also for agriculture and the food sector as a whole.
In crafting sound domestic climate policy, it is important to bring togther these aspects of the connection between agriculture and climate change.