CATTLE & CLIMATE CHANGE
How do cattle drive climate change?
Cattle are a type of mammal that are able to break down plants rich in cellulose through fermentation and digestion. This process allows them to obtain nutrients from grazing in fields and pastures. However, grass is more difficult to digest than grain, and so grazing livestock tend to produce more methane–hence the notorious “cow burps and farts” problem–a greenhouse gas with much greater warming potential than carbon dioxide.
How much do cattle emissions contribute to climate change?
It is estimated that the livestock sector as a whole contributes to about 14.5 percent of total man-made greenhouse gas emissions; beef and milk production make up the majority of this. Agriculture and livestock production represents a relatively smaller portion of emissions in the United States, making up around nine percent nationwide. While methane from natural gas and petroleum decreased from 1990 to 2015, methane produced and released by cows has increased about 78 percent, respectively. Simply put, emissions from cattle and livestock production represent a significant and increasing problem.
Can cattle’s impact be offset by good grazing and management practices?
It is argued that grazing cattle offsets such emissions by helping sequester more carbon in the soil. Grazing livestock nibble at grass, encouraging plant growth and deeper roots. If these plants are left undisturbed, the carbon in the plants’ biomass can stay stable in the ground rather than be re-emitted into the atmosphere. Cattle don’t need to consume crops like corn and grain, which are typically associated with climate change-driving deforestation, land use change, and nitrogen-based fertilizer use. When well-managed, grazing production systems allow livestock manure, containing carbon and nitrogen, to re-enter the soil, fostering increased plant growth and sequestering more carbon. Livestock manure can replace energy-intensive synthetic fertilizers, thus avoiding greenhouse gas emissions. Livestock also have an important place in food security, offering a source of income and dietary diversity to many across the world.
There are many proclaimed benefits of grass-fed beef, which deserve their own research and exploration; animal welfare, more fertile soil, increased biodiversity, healthier and more nutritious meat, and reduced use of fertilizer and antibiotics are just a few of the advantages. However, limiting the discussion to cattle’s net greenhouse gas emissions, there are a few problems with relying on grass-fed beef as a climate solution.
Soil carbon storage is time-limited, reversible, and depends on very specific conditions. Soils reach “carbon equilibrium” within a few decades, after which no more carbon can be drawn down from the atmosphere (without a corresponding loss of soil carbon). Carbon stored in soils can also be lost into the atmosphere as a result of poor grazing management, a change in land use, or natural causes such as drought. The amount of carbon soil can hold also depends on a number of factors, including type of soil, the regional climate, how often the soil is disturbed, and the kind of vegetation and soil microbes present.
Furthermore, efforts to sequester carbon in soil can be at odds with management practices to limit nitrous oxide emissions–a greenhouse gas with 298 times the warming potential of carbon dioxide over the course of 100 years. Increasing nitrogen (from manure or other sources) promotes plant growth, which fosters carbon sequestration, but also potentially causes more emissions of nitrous oxide, undermining the climate benefit of carbon storage.
Grass-fed beef also supplies a very small portion of the protein we eat – just 1 gram of the 31 grams of protein from animal sources the average person is estimated to consume daily by 2050 – but livestock grazing takes up roughly 26 percent of the world’s terrestrial land, according to the FAO. Grassland is not a free and unlimited resource – it could be used for many other beneficial purposes – and even grassland can carry an environmental cost from fertilizer inputs or deforestation.
Cattle are a type of mammal that are able to break down plants rich in cellulose through fermentation and digestion. This process allows them to obtain nutrients from grazing in fields and pastures. However, grass is more difficult to digest than grain, and so grazing livestock tend to produce more methane–hence the notorious “cow burps and farts” problem–a greenhouse gas with much greater warming potential than carbon dioxide.
How much do cattle emissions contribute to climate change?
It is estimated that the livestock sector as a whole contributes to about 14.5 percent of total man-made greenhouse gas emissions; beef and milk production make up the majority of this. Agriculture and livestock production represents a relatively smaller portion of emissions in the United States, making up around nine percent nationwide. While methane from natural gas and petroleum decreased from 1990 to 2015, methane produced and released by cows has increased about 78 percent, respectively. Simply put, emissions from cattle and livestock production represent a significant and increasing problem.
Can cattle’s impact be offset by good grazing and management practices?
It is argued that grazing cattle offsets such emissions by helping sequester more carbon in the soil. Grazing livestock nibble at grass, encouraging plant growth and deeper roots. If these plants are left undisturbed, the carbon in the plants’ biomass can stay stable in the ground rather than be re-emitted into the atmosphere. Cattle don’t need to consume crops like corn and grain, which are typically associated with climate change-driving deforestation, land use change, and nitrogen-based fertilizer use. When well-managed, grazing production systems allow livestock manure, containing carbon and nitrogen, to re-enter the soil, fostering increased plant growth and sequestering more carbon. Livestock manure can replace energy-intensive synthetic fertilizers, thus avoiding greenhouse gas emissions. Livestock also have an important place in food security, offering a source of income and dietary diversity to many across the world.
There are many proclaimed benefits of grass-fed beef, which deserve their own research and exploration; animal welfare, more fertile soil, increased biodiversity, healthier and more nutritious meat, and reduced use of fertilizer and antibiotics are just a few of the advantages. However, limiting the discussion to cattle’s net greenhouse gas emissions, there are a few problems with relying on grass-fed beef as a climate solution.
Soil carbon storage is time-limited, reversible, and depends on very specific conditions. Soils reach “carbon equilibrium” within a few decades, after which no more carbon can be drawn down from the atmosphere (without a corresponding loss of soil carbon). Carbon stored in soils can also be lost into the atmosphere as a result of poor grazing management, a change in land use, or natural causes such as drought. The amount of carbon soil can hold also depends on a number of factors, including type of soil, the regional climate, how often the soil is disturbed, and the kind of vegetation and soil microbes present.
Furthermore, efforts to sequester carbon in soil can be at odds with management practices to limit nitrous oxide emissions–a greenhouse gas with 298 times the warming potential of carbon dioxide over the course of 100 years. Increasing nitrogen (from manure or other sources) promotes plant growth, which fosters carbon sequestration, but also potentially causes more emissions of nitrous oxide, undermining the climate benefit of carbon storage.
Grass-fed beef also supplies a very small portion of the protein we eat – just 1 gram of the 31 grams of protein from animal sources the average person is estimated to consume daily by 2050 – but livestock grazing takes up roughly 26 percent of the world’s terrestrial land, according to the FAO. Grassland is not a free and unlimited resource – it could be used for many other beneficial purposes – and even grassland can carry an environmental cost from fertilizer inputs or deforestation.
