Livestock and climate change are directly and substantially linked. Livestock systems both produce greenhouse gas (GHG) emissions through natural processes and are also powerful agents in removing atmospheric carbon dioxide (CO2). The net effect relates to management with evidence establishing that soil carbon sequestration through grazing management can substantially reduce atmospheric CO2 levels, second only to drastic reduction in fossil fuel use in reversing global warming.


The natural systems that influence all life on earth are both elegant and complex. While greenhouse gases (GHG) are most often discussed they are intricately linked with plant growth, soil health and microorganism diversity, impacting soil carbon content and water holding capacity. Managed and unmanaged human interaction with these cycles impacts the climate through emissions, water cycles, soil nutrients, biodiversity above and below ground and through plant, animal and human interactions.


Atmospheric carbon dioxide (CO2) is utilised by plants through photosynthesis with CO2 broken down to organic carbon and oxygen released to the atmosphere. Humans rely on this cycle for the oxygen they breathe, whereas plants rely on the organic carbon which is exchanged for soil nutrients (including nitrogen, phosphorus, potassium and many, many others) with soil microorganisms and fungi.


As plants grow nutrients including carbon are transferred to both above ground structures and roots. The plants can die, be harvested as crops or consumed by animals, insects, earthworms and soil microorganisms with the nutrients continually recycled in plant and animal material with a proportion returned to the atmosphere. Soil organic carbon stocks (SOC) are increased by plant growth and the accumulation of dead roots and microorganisms.


Plant growth is stimulated by grazing or mechanical harvesting with grazing providing the substantial additional benefit of returning valuable nutrients through manure and urine and the mechanical effect of trampling these and plant litter into the soil. Grazing ruminant animals can utilise high cellulose fibrous material that is not digestible by humans. Well managed ruminant grazing mirrors the historic natural pattern of intense short duration grazing where herds of animals grazed and continually moved, by rotating mobs of cattle or sheep through small areas. Evidence establishes that these practices greatly increase plant growth, plant and microorganism biodiversity and result in substantial improvement in soil health, biodiversity, water holding capacity and soil organic carbon stocks.


On a global basis more carbon is stored in soil than in all above ground vegetation and in the atmosphere combined. The introduction of agriculture has resulted in depletion of soil carbon through cropping, overgrazing and poor management practices. These problems however also represent substantial opportunity to transfer atmospheric CO2 to replenish soil organic carbon in quantities that substantially reduce global warming.


Much attention has been paid to the role of methane in GHG emissions, with far less appreciation of the methane cycle and net impact after sequestration. Methane is a powerful GHG but also has a short life cycle being converted to CO2 within around 10 years then recycled. Whereas fossil fuel use transfers sequestered ancient carbon to the atmosphere as CO2 with no return path, livestock methane emissions are part of a natural biogenic cycle that removes and sequesters substantially more CO2 from the atmosphere to soils than is released under well managed systems.


SOC is also directly linked to soil health and fertility being associated with larger populations of biodiverse organisms, improved soil structure, increased aeration and increased water holding capacity which reduces runoff and increases drought resistance.
Livestock manures and urine are also valuable fertilizers that stimulate microorganism and fungi proliferation in contrast to synthetic chemical fertilizers which disrupt the complex soil microfloral systems. While grazing provides direct manure application, manures liquid effluents and composted material from intensive animal systems are also returned to pastures, crops and horticulture in massive quantities that reduce the use of synthetics.