Global Farm Animal Production and Global Warming: Impacting and Mitigating Climate Change
Koneswaran, Gowri, Nierenberg, Danielle, Environmental Health Perspectives
Although much evidence has been amassed on the negative impacts of animal agricultural production on environmental integrity, community sustainability, public health, and animal welfare, the global impacts of this sector have remained largely underestimated and underappreciated. In a recent review of the relevant data, Steinfeld et al. (2006) calculated the sector's contributions to global greenhouse gas (GHG) emissions and determined them to be so significant that--measured in carbon dioxide equivalent--the emissions from the animal agricultural sector surpass those of the transportation sector.
Global warming and climate change. The three main GHGs are C[O.sub.2], methane (C[H.sub.4]), and nitrous oxide ([N.sub.2]O) (Steinfeld et al. 2006). Although most attention has focused on C[O.sub.2], methane and [N.sub.2]O--both extremely potent GHGs--have greater global warming potentials (GWPs) than does C[O.sub.2]. By assigning C[O.sub.2] a value of 1 GWP, the warming potentials of these other gases can be expressed on a C[O.sub.2]-equivalent basis (Paustian et al. 2006; Steinfeld et al. 2006): CH4 has a GWP of 23, and N20 has a GWP of 296.
Many impacts of global warming are already detectable. As glaciers retreat, the sea level rises, the tundra thaws, hurricanes and other extreme weather events occur more frequently, and penguins, polar bears, and other species struggle to survive (Topping 2007), experts anticipate even greater increases in the intensity and prevalence of these changes as the 21st century brings rises in GHG emissions. The five warmest years since the 1890s were 1998, 2002, 2003, 2004, and 2005 [NASA (National Aeronautics and Space Administration) 2006]. Indeed, average global temperatures have risen considerably, and the Intergovernmental Panel on Climate Change (IPCC 2007c) predicts increases of 1.8-3.9[degrees]C (3.2-7.1[degrees]F) by 2100. These temperature rises are much greater than those seen during the last century, when average temperatures rose only 0.06[degrees]C (0.12[degrees]F) per decade (National Oceanic and Atmospheric Administration 2007). Since the mid-1970s, however, the rate of increase in temperature rises has tripled. The IPCC's latest report (IPCC 2007b) warns that climate change "could lead to some impacts that are abrupt or irreversible."
Anthropogenic influences. Although some natural occurrences contribute to GHG emissions (IPCC 2007c), the overwhelming consensus among the world's most reputable climate scientists is that human activities are responsible for most of this increase in temperature (IPCC 2007a). The IPCC (2007a) concluded
with high confidence that anthropogenic warming over the last three decades has had a discernible influence on many physical and biological systems.
Although transportation and the burning of fossil fuels have typically been regarded as the chief contributors to GHG emissions and climate change, a 2006 report, Livestock's Long Shadow: Environmental Issues and Options [Food and Agriculture Organization of the United Nations (FAO) 2006], highlighted the substantial role of the farm animal production sector. Identifying it as "a major threat to the environment" (FAO 2006), the FAO found that the animal agriculture sector emits 18%, or nearly one-fifth, of human-induced GHG emissions, more than the transportation sector. (Steinfeld et al. 2006).
Our objective was to outline the animal agriculture sector's share of global GHG emissions by synthesizing and expanding upon the data reported in Livestock's Long Shadow (FAO 2006) with more recent reports from the IPCC, data from the U.S. Environmental Protection Agency (EPA), and studies on GHGs from agriculture and mitigation strategies [Cederberg and Stadig 2003; International Federation of Organic Agriculture Movements (IFOAM) 2004; IPCC 2007a, 2007b, 2007c; McMichael et al. 2007; Ogino et al. 2007; U.S. EPA 2007a; Verge et al. 2007]. We also investigated links between this sector and the far-reaching impacts of climate change on conflict, hunger, and disease, while underscoring the roles of animal agriculture industries, policy makers, and individual consumers in mitigating this sector's contributions to climate change and global warming. …