Global overview of greenhouse gases and agriculture
In both industrialized and developing nations, agricultural production of greenhouse gases (GHG) is a significant component of worldwide GHG emissions. There are major contributions to methane production from livestock grazing and rice farming, as well as incomplete combustion of petroleum products in mechanized agricultural equipment. In developing countries agricultural production of greenhouse gases is a much higher percentage of total GHG emissions than for developed countries. For example, rice farming in China and Southeast Asia and livestock grazing in several South American countries contributes proportionately more agricultural GHG than corresponding farming activity in most Western countries. Elimination of overgrazing practises and reduction of dependence of rice farming provide significant opportunities for reducing GHG emissions.
There are also large contributions to carbon dioxide emissions from mechanised farm equipment, as well as from the manufacture and transport of massive amounts of pesticides, herbicides and fertilizers. Thus reduction of intense use of these chemicals presents a major opportunity for lowering the total GHG emissions from agriculture worldwide.
Summary of U..S. Congressional Research Service report
This report examines the implications for agriculture of the ongoing but inconclusive debate about global climate change. In that debate, agriculture’s role is multifaceted. Agriculture is both a source of several greenhouse gases (GHGs) and a “sink” for absorbing carbon dioxide, the most common GHG, thereby partly offsetting emissions. Overall, U.S. agriculture is a comparatively modest source of U.S. GHG emissions: it accounts for approximately seven percent of U.S. emissions, while sectors such as transportation and electricity generation account for much larger shares. Agriculture’s GHG emissions are principally in the form of methane and nitrous oxide emissions.
Whatever the current or future Congresses may do regarding climate legislation, interest in existing and prospective responses by government and others will continue. Administration efforts to develop policies and strategies to address GHGs and climate change have been underway for some time. Two actions by the Environmental Protection Agency (EPA) have drawn the attention of the agriculture industry. One is regulating emissions of GHGs under the Clean Air Act (CAA) and subsequent GHG emission standards for new motor vehicles which, in turn, trigger certain CAA permitting requirements. A second, related action is a rule to require reporting of GHG emissions by certain facilities. Regarding both, EPA took steps to focus on the largest emitters and ensure that few agricultural sources would be subject to new GHG requirements. Still, EPA’s overall initiatives have been widely criticized, and the 111th Congress intervened through a funding bill to largely exclude agriculture from EPA’s regulatory requirements. During the 111th Congress, the House passed a comprehensive climate change bill (H.R. 2454), and a Senate committee reported a companion (S. 1733). Although no legislation was enacted, both bills included provisions excluding agriculture from regulatory requirements and promoting agricultural practices to reduce or offset emissions from regulated sources.
Traditionally, practices such as conservation tillage have been used for soil conservation and water quality improvement, but their value for climate change abatement or mitigation is receiving increased attention. A number of strategies, technologies, and practices exist to reduce methane and nitrous oxides emissions at the farm level, but implementation faces financial and monitoring challenges.
Programs administered by the U.S. Department of Agriculture (USDA) provide financial incentives and technical assistance to encourage implementation of certain farming practices. While the focus of most programs is not on GHG emission reduction, USDA is giving greater attention to GHGs in administering its suite of existing programs.
Results of the 2010 congressional elections have altered political dynamics in Congress on many issues, and leadership of both political parties have indicated that neither currently plans to pursue comprehensive approaches to addressing climate change in the 112th Congress, although some elements of previous proposals may move through the legislative process. How agriculture fits in these discussions—both as a source of GHG emissions and contributions that the sector can make to mitigating climate change—has drawn interest in the past and likely will do so again.
The summary section was taken from the Congressional Research Service Report R41530 by Claudia Copeland, Megan Stubbs, and Kelsi Bracmort