Meat consumption research – Part 5 Impact on the environment

See Introduction/aim of research for the background to this work.

Due to there being fairly extensive information about agriculture’s impact on the environment and my focus on some of the less investigated areas, this section only briefly outlines some of the major environmental impacts.

According to research carried out by FAO (2006), around 70% of the total agricultural land area is used in the raising of livestock. That area accounts for about 30% of the total ice-free land surface. However, much of this land is marginal and is used for grazing and would not be productive for other types of agriculture. Raising of livestock utilises about a third of the total arable land supply for growing of feed-crops. Given these figures, it is clear that continued expansion of the industry presents a challenge in terms of environmental and food supply security as either more land needs to be used or more crops needs to go towards animal feed. Intensive livestock production is still mostly the preserve of the more economically advanced countries and the livestock feed is also mainly produced in OECD countries. Current levels of livestock production let alone expansion look unsustainable due to their dependence on large energy inputs, heavy impact on the environment and dwindling global water security.

Energy use

As modern agriculture is highly dependent on considerable external energy inputs, the growing of feed-crops is often the most energy-intensive part of livestock production. This is compounded with production of animals that are inefficient at converting feed to meat, such as grain-fed beef.

Mechanisation of farming slashed the amount of human and animal labour that was necessary, replacing the power with sources such as diesel and electricity. Chemical fertiliser, which has become essential to modern industrial agriculture, is very energy intensive to produce. Around 100 million tonnes of chemical fertiliser is used globally per year which is estimated to account for 1% of the world’s total energy use (FAO 2006). Further energy is required to produce pesticides, to transport inputs and outputs, pump irrigation water, to plough fields, and harvest. The actual livestock raising does not generally use a lot of energy. However, processing, storing and transporting the final product is highly energy-intensive when producing for most modern supply chains.

With growing global demand for energy, constrained supplies and political instability in many regions of production, the high dependence of the modern food system on external energy inputs exposes it to considerable future risk.

Emissions and pollution

Overall, FAO (2006) estimate that livestock production is responsible for 18% of total anthropogenic greenhouse gas emissions, including 9% of carbon dioxide emissions, 35-40% of methane emissions and around 65% of nitrous oxide and ammonia emissions. Some of these emissions come from the energy use already mentioned, some from the animals themselves. Methane is a much more potent greenhouse gas than carbon dioxide and FAO (2006) estimate that 86 million tonnes is emitted during feed digestion by livestock, especially ruminants. They calculate a further 18 million tonnes is emitted from animal manure.

However, the most worrying estimate that FAO (2006) calculated was concerning land use changes. Destruction of rainforest to create grazing or feed-crop land could be responsible for 2.4 billion tonnes of CO2 emissions. This compares to their estimate of 41 million tonnes of CO2 emissions for global fertiliser use. While their estimate may have a large margin of error, the orders of magnitude involved highlight the serious need to prevent further loss of such land to agriculture if only as a precautionary principle.

Both the feed-growing and livestock operations can be significant polluters of the local and greater environment. Fertiliser run-off is a serious problem polluting many small water ways, large rivers and now even a large part of the Bay of Mexico. Pesticides can be highly dangerous and virtually impossible to apply without affecting the wider environment. Animal wastes can be a significant danger due to the large number of pathogens they can contain. Often environmental restrictions on modern concentrated animal feeding operations (CAFOs) are lax or less restrictive than those that apply to other industries.  For example, animal waste can often be discharged straight into the environment while human waste is required to undergo significant processing before discharge.

Land use and deforestation

Expansion of livestock production is encouraging a spread of agriculture into virgin territories such as tropical rainforest. This opens up new grazing land or land for planting crops such as soya which are used for animal feed. At the same time, agricultural land around the world is being lost to roads and growing cities. In many areas agricultural land is being degraded as top soil is lost, salt levels or other pollutants build up. In some areas land is being lost to desertification, hastened by climate changes.

Agricultural expansion threatens the few remaining large wilderness areas which contain a wealth of biodiversity. These areas also seem to play an important role in the global carbon cycle and climate system. Therefore, continued destruction would be tragic and potentially highly dangerous.

Water supplies

Agriculture is by far the greatest use of fresh water in the world. FAO (2006) estimate that 70% of fresh water resources go to agriculture. Much of the expansion of agriculture that modern methods and inputs allowed were only possible with the aid of modern water extraction and irrigation systems. Unfortunately, in many parts of the world this water extraction is far from sustainable at current levels. In many areas aquifers are being depleted much faster than they are being replenished, making the water more and more expensive to obtain and threatening the long-term viability of such agriculture. One of the reasons for the over-extraction is that so many of the crops modern agriculture rely on require generous amounts of water. These crops are then grown in areas that would not naturally provide that amount of water. FAO (2006) estimate that 93% of fresh water resource depletion is caused by agriculture.

The greatest use of water in livestock production is its use in agricultural feed-crop production. These crops will have a significant water use in their production.  When fed to inefficient feed to meat converters such as cows, the water resources behind that meat production becomes compounded. From figures found by Singer & Mason (2006) it is likely that US beef production requires at least half a tonne of water per kilo of meat.

The perilous state of fresh water supplies in some, drier areas of the world is a considerable source of concern. Already there have been serious disputes over access and use of resources that can originate in one state but flow through and are essential to others. As populations and agricultural use grows, water insecurity can quickly become a matter of national security and conflict.

With the water resources used in the production of food, export of food can be seen as essentially an export of water.  This can be highly advantageous to drier countries with growing populations.  However, reducing water security in many areas threatens this trade and the people who are becoming reliant on it.


Livestock, Environment and Development Initiative. United Nations Food and Agriculture Organization (FAO). 2006. Livestock’s Long Shadow. Environmental Issues And Options.

Singer, Peter and Mason, Jim. 2006. The way we eat: Why our food choices matter. Rodale.


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