Around 71% of the earth’s surface is covered by water, mostly in oceans, with 29% land. From 2021 FAO data the world total land area is about 13 billion hectares (ha), excluding Antarctica and inland waters. Out of the world total land area, agricultural land, forest land and other land (barren and desert areas, urban land and infrastructure) occupy about one-third each. In 2021, the area of agricultural land was 4.8 billion ha while forest land and other land area covered 4.1 billion ha each. 


Only a third of global agricultural land is arable and suitable for growing crops, with a much smaller proportion able to support continuous cropping. The remaining two thirds, 3.2 million ha, of non-arable land, is pasture or meadows utilised for grazing. These percentages vary widely by region due to climate, topography and urban area emphasising that actual and optimal land use, together with environmental interaction, must be considered at the micro localised area level.  Food production for both plants and animals have various impacts on the environment including land and water usage, greenhouse gas emissions, impact on biodiversity and water systems. 

  Ruminant livestock species such as sheep, goats and cattle, have the unique ability to convert material that is inedible by humans into high quality nutrient dense human food, providing a vital role in upcycling human-inedible pasture and herbage. Grazing stimulates plant growth with photosynthesis dependent on atmospheric CO2. This natural system transfers carbon from the atmosphere to organic carbon in plant material both above and below ground. Ingested plant material is utilised by ruminants for maintenance, milk and body components including muscle, fat and other tissues with a proportion excreted as urine and manure.
A by-product of rumen fermentation is methane, a short term greenhouse gas (GHG) that is recycled back to CO2 and reconverted to plant material through photosynthesis, completing a natural cycle.


Carbon transferred though plant roots to the soil is exchanged for needed nutrients with soil microbes and fungi which again represent a natural symbiotic system essential for healthy soil and plant production. Historically it is believed that megafauna and ruminant species such as bison in USA and many African wildlife species were instrumental in creating highly fertile global soils and the savannah and rangelands with grass, shrubs and trees that exist today through grazing in high numbers, with the herd continuously moving. The amount of carbon sequestered in soil or returned to the atmosphere through grazing, tillage or erosion is now dependent on management practices by farmers and graziers.


 While historically farming practices and overgrazing have often resulted in substantial soil and ecosystem degradation, regenerative agricultural practices result in substantial carbon and carbon equivalent sequestration in soils with global potential to mitigate industrial atmospheric carbon level increases. There is more than double the amount of carbon stored in soils than in the atmosphere or in herbage. Soil is the most biodiverse singular habitat with improved soil health the key to increased biodiversity above and below ground, to greater water capture (thereby mitigating the warming potential of water vapour in the atmosphere), of increased high quality human food production and of reversing current climate change trends. There is clear evidence that cessation of grazing causes biodiversity loss and homogenization of soil food webs substantiating a critical role for well managed grazing systems.


Intensive livestock systems also have environmental impact and are often criticised without consideration of context or evidence relating to local conditions and management. As with poor cropping or grazing management intensive dairies, feedlots and non-ruminant livestock systems can clearly lead to environmental damage. However, these systems often complement grazed systems by enabling livestock to be carried through seasons where plant growth is low or non-existent, or pastures would be damaged by pugging or overgrazing. Further considerations relate to the diets fed, which often include high proportions of human inedible food and crop by-products, adding nutrients contained in these products back into the human food chain, reducing waste and waste generated emissions. It is estimated that 86% of all livestock feed is human inedible material. Effective utilisation of manure and effluent is also central to mitigating environmental damage and often central to a circular nutrient supply chain. However, the net impacts of such circularity among different sectors of food production are not always captured in biophysical models and sustainability frameworks.


A final consideration in providing adequate nutrition for a projected 10 billion global population in concert with improving environmental impact is the critical impact of productivity. All animals prioritise food intake to basic maintenance, with intake beyond this utilised in growth or production such as meat, milk or wool. As maintenance needs are fixed the higher the intake the greater the % of food that is utilised in producing meat, milk or fibre. Consequently, for grazed and intensive systems, higher productivity increases efficiency and reduces feed utilised per unit of production. Practical application of continuing scientific advances in genetics, animal health and management systems is delivering improved human food and environmental outcomes.