Impact of livestock in increasing greenhouse gases

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Livestock production plays a key role in the life of farmers. In global food production it provides food, income, employment and many other contributions to rural development and also has part of local landscapes and ecosystems for eras. In human society it also contributes by food, employment, nutrients and incomes which are helpful for the economy of the country. Animals for the sake of food vastly contribute in the production of greenhouse gases so there is a need for the awareness that rapid global production and feasting greatly influence the discharge of Green House Gases (GHGs). These greenhouse gases emitted from livestock more than 18 per cent which is a higher share than transport.

According to studies, the main source of GHGs is livestock accounts 9 per cent land use changes carbon dioxide which is caused by deforestation for the sake of livestock feed, 37 percent methane are produce by the enteric fermentation of animal and also from manure management which produce the N2O. These all the factors which share of total global GHG emissions. Livestock is responsible for much larger and higher potential for atmospheric warming and production of gases. The World Watch Institute disputed that GHGs emitted from livestock is nearer to 51 per cent of global GHG emissions.

In contrast to general trends of GHG emissions, carbon dioxide (CO2) is only a small component of emissions in animal agriculture. The largest share of GHG emissions is from two other gases – methane (CH4) and nitrous oxide (N2O). These are not only emitted in large quantities, but are also potent greenhouse gases, with a global warming potential (GWP3) of 25 using a 100-year timeframe for methane and a GWP of 296 for N2O. Globally, about 9 per cent of emissions in the entire agricultural sector consist of CO2, 35-45 per cent of methane and 45-55 per cent of nitrous oxide. The main sources of CH4 are the enteric fermentation of ruminants and releases from stored manure, which also emits N2O. Cattle are by far the largest contributors to global enteric CH4 emissions, as they are the most numerous and have a much larger body size relative to other species such as sheep and goats. Out of the 1.43 billion cattle in 2010, 33 per cent were in Asia, 25 per cent in South America and 20 per cent in Africa. Asia is the main source of CH4 emissions, with almost 34 per cent of global emissions. China is a major source of enteric emissions and, while Indians are low meat consumers, India as a country also has high levels of CH4 emissions. Latin America follows with 24 per cent and Africa with 14.5 per cent. China, Western Europe and North America are the regions with the highest emissions from manure. The application of manure as well as N fertilizers to agricultural land increases emissions of N2O. Furthermore, N2O as well as CO2 are released during production of chemical N fertilizers. Some CO2 is also produced on farms from fossil fuels and energy usage and by the exhalation of animals but “beef had by far the highest GHG emissions with 22.6 kg CO2-eq/kg” in comparison to other products such as pork (2.5), poultry (1.6) and milk (1.3).

A study in the UK found that emissions from beef amount to 16 kg CO2-eq/kg beef compared to 0.8 kg CO2-eq/kg of wheat. In Europe (the EU-27), for example, enteric fermentation was the main source (36 per cent) of GHG emissions in the livestock sector, followed by N2O soil emissions (28 per cent). Livestock are also responsible for almost two-thirds (64 per cent) of anthropogenic ammonia emissions, which contribute significantly to acid rain and acidification of ecosystems.

Under natural conditions which were maintained for thousands of years and still widely exist around the world, there is a closed, circular system, in which some animals feed themselves from landscape types which would otherwise be of little use to humans. They thus convert energy stored in plants into food, while at the same time fertilizing the ground with their excrements. Although not an intensive form of production, this co-existence and use of marginal resources was, and still is in some regions, an efficient symbiosis between plant life, animal life and human needs. In many parts of the world “traditional” forms of animal agriculture have, to a certain extent, been replaced by a “landless”, high-density, industrial-styled animal production system, exemplified by the phenomenon known as Concentrated Animal Feeding Operations (CAFO). Those “factories” hold hundreds or thousands of animals, and often buy and import animal feed from farmers far away. The feeding of livestock, and their resulting manure, contributes to a variety of environmental problems, including GHG emissions. Furthermore, this manure is generated in huge quantities. In the USA alone, operations which confine livestock and poultry animals generate about 900 million tons of manure annually, which is three times the amount of human sanitary waste produced annually (EPA 2013). Insufficient amounts of land on which to dispose of the manure results in the runoff and leaching of waste into and the contamination of surface and groundwater

Strategies how to overcome greenhouse gases:

Livestock in many regions of the world, and especially in dry areas, acts as a “savings bank”: a principal way of making use of a harsh environment, a “setting aside” of food (and more generally, the value of this resource) for dry times, a main source of high-protein food. It contributes important non-food goods and services. Livestock rearing and consumption in these regions is a way of life, critical to pastoralists identity, and should be protected and supported. At present, the ecological foundations of agriculture are being undermined. At the same time, industrial agriculture is itself contributing to environmental problems such as climate change. However, here are mitigation techniques to reduce the impact of both intensive and non-intensive animal production on climate. Many of them have costs of implementation substantially reducing their potential. A reduction of non-carbon dioxide emissions of up to 20 percent should, however, be possible at realistic costs. Other mitigation solutions include improved feedstock efficiency and diets; the reduction of food waste and improved manure management.

Changes in human diet may also be a practical tool to reduce GHG emissions. They are however more dependent on grain and soy-products and may thus still have a negative impact on GHG emissions. Scientists agree that in order to keep GHG emissions to 2000 levels the projected 9 billion inhabitants of the world (in 2050) need to each consume no more than 70-90 grams of meat/day. To meet this target, substantial reductions in meat consumption in developed countries and constrained growth in demand in developing ones would be required.

A reduction in the consumption of meat, especially red meat, could have multiple health benefits, as there is clear evidence of a link between high meat diets and bowel cancer and heart disease. A study modeling consumption patterns in the United Kingdom estimates that a 50 per cent reduction in meat and dairy consumption, if replaced by fruit, vegetable and cereals, could result in a 19 per cent reduction in GHG emissions and up to nearly 43,600 fewer deaths per year in the UK.

The writers are associated with the Department of Plant Pathology, University of Agriculture Faisalabad, Pakistan. They can be reached at <>


Published in: Volume 05 Issue 06

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