Forum: Climate, Ecological, and Social Costs of Livestock Grazing on Western Public Lands.

Grazing by domestic livestock is the most widespread use of public lands in the American West (USA) and their effects on climate change and ways to mitigate those effects are of interest to land managers, policy makers, and the broader public. Kauffman et al. (2022a) provided a meta-analysis of the ecosystem impacts, greenhouse gas (GHG) emissions, and social costs of carbon (SCC) associated with livestock grazing on public lands in the western USA. They determined that GHG emissions from cattle on public lands equaled 12.4 million t CO2e/year. At the scale of land use planning utilized by federal agencies, GHG emissions associated with allocated livestock numbers will typically exceed US Environmental Protection Agencies' reporting limits (25,000 t) for certain industrial greenhouse gas emitters. As such, these are essentially unreported sources of GHG emissions from public lands. Using the US government's most recent SCC estimate of $51/t, Kauffman et al. (2022a) determined the total SCC of cattle grazing on public lands to be approximately $264-630 million/year. However, recent advances in the determination of SCC reveal this is to be an underestimate. Using the latest science results in an estimated SCC of $1.1-2.4 billion/year for grazing on public lands. Furthermore, the SCC borne by the public exceeds the economic benefits to private livestock permittees by over $926 million/year. Cessation of public lands grazing is an environmentally and economically sound mitigation and adaptation approach to addressing the climate crisis; an approach that will also facilitate restoration of the myriad of ecosystem services provided by intact wildland ecosystems.

Livestock Use on Public Lands in the Western USA Exacerbates Climate Change: Implications for Climate Change Mitigation and Adaptation.

Public lands of the USA can play an important role in addressing the climate crisis. About 85% of public lands in the western USA are grazed by domestic livestock, and they influence climate change in three profound ways: (1) they are significant sources of greenhouse gases through enteric fermentation and manure deposition; (2) they defoliate native plants, trample vegetation and soils, and accelerate the spread of exotic species resulting in a shift in landscape function from carbon sinks to sources of greenhouse gases; and (3) they exacerbate the effects of climate change on ecosystems by creating warmer and drier conditions. On public lands one cow-calf pair grazing for one month (an "animal unit month" or "AUM") produces 875 kg CO2e through enteric fermentation and manure deposition with a social carbon cost of nearly $36 per AUM. Over 14 million AUMs of cattle graze public lands of the western USA each year resulting in greenhouse gas emissions of 12.4 Tg CO2e year-1. The social costs of carbon are > $500 million year-1 or approximately 26 times greater than annual grazing fees collected by managing federal agencies. These emissions and social costs do not include the likely greater ecosystems costs from grazing impacts and associated livestock management activities that reduce biodiversity, carbon stocks and rates of carbon sequestration. Cessation of grazing would decrease greenhouse gas emissions, improve soil and water resources, and would enhance/sustain native species biodiversity thus representing an important and cost-effective adaptive approach to climate change.