Livestock farming accentuates the greenhouse effect and deforestation

Mis à jour : mars 1

In brief

  • Livestock farming is responsible for 14.5% of greenhouse gas emissions.

  • And 63% of deforestation in the Amazon.

  • The 5th IPCC report recommends a significant reduction in meat consumption: following the recommendations of the Harvard Medical School would be as effective as halving the world's automobile fleet.

  • The three largest meat producers in the world combined have a carbon footprint greater than that of France alone.

  • A vegan emits 2.5 times less GHG through his or her diet than a western omnivore.

  • A change in diet can provide ecological benefits on a scale that would not be possible to achieve solely through changes in agricultural production practices.

Greenhouse gas emissions from livestock production are more than transportation fuel consumption

In 2006, an FAO report, Livestock's Long Shadow, revealed that livestock production as a whole produces a significant amount of greenhouse gases (GHGs), about 18 percent of man-made emissions. In a later report, Tackling Climate Change Through Livestock (FAO, 2013), calculations based on more precise data put the contribution of livestock to anthropogenic greenhouse gas emissions at 14.5%, of which 8.8% was from cattle alone. This is slightly more than the direct emissions (fuel consumption) from the transportation sector (IPCC, 2014).

A report by the IATP (Institute for Agricultural and Trade Policy) and GRAIN (International Farmers' Support Association) found that most of the world's 35 largest meat and milk producing companies do not report their greenhouse gas emissions (GRAIN, 2018). Using public data, the authors of this report were able to estimate that the three largest producers combined (JBS-Friboi, Tyson Foods and Cargill) alone emit more greenhouse gases than France.

The livestock sector emitted an estimated total of between 7.1 and 8.1 billion tonnes of CO2 equivalent in 2010 (FAO, 2014 and 2018). This represents between 14.5% and 16.5% of the 49 billion tonnes of CO2 equivalent emitted by all human activities in that year (IPCC, 2014). The Paris Accord, the first universal climate agreement, calls for these global emissions to be reduced by 38 billion tons of CO2 equivalent by 2050 to limit the rise in temperature to 1.5°C.

However, the meat and dairy sector is today pursuing its growth and profitability objectives: to produce more and more to meet growing global demand. If this trend continues, by 2050 livestock production alone will account for more than 80% of the maximum global emissions to 1.5°C. In other words, this would mean that all other human activities (transport, housing, industry, etc.) would have to emit four times less greenhouse gases than livestock farming alone. It is therefore essential to act on this sector by modifying our agricultural and food model.

Key figures

The livestock sector produced between 7.1 and 8.1 billion tonnes of CO2 equivalent, or about 1/7 of all greenhouse gas emissions.

These GHG emissions can be broken down as follows. 45% are attributable to food production and transport (of which 9% are attributable to deforestation linked to the expansion of crops and pastures). 39% come from the gastric fermentation of ruminants. 10% is from the storage and use of manure. 6 % are caused by transport, slaughter of animals and storage of animal products.

Most of the emissions are due to the rearing of ruminants. Producing 1 kg of protein in the form of beef emits an average of 290 kg of C02 eq. compared to less than 50 in the form of pork, chicken or eggs.

Source: IPCC.

NB: "dairy cattle" are exploited for their milk, but also for their meat.

A 2011 report predicts that, between 2005 and 2050, the demand for meat will increase by 73% and that for milk by 58% (FAO, 2011).

Breeding is not done in the forest

Extensive livestock farming and soy exported as cattle feed are the main cause of deforestation in Brazil (Margulis, 2004). Greenpeace claims that cattle farming is responsible for 63% of the destruction of the Amazon rainforest (Greenpeace, 2016).

With an area of 5.5 million km², the Amazon rainforest is the largest area of primary tropical forest on the planet. Over the past 40 years, nearly 800,000 km2 of Amazonian forest have been destroyed. Thanks to the efforts of the Brazilian government, the rate of deforestation has slowed down since the mid-2000s and now stands at around 6,000 km² per year in Brazil, which is still very high.

Deforestation accounted for 12% of global GHG emissions between 2000 and 2005 (Congressional Budget Office, 2012), a figure that has slightly decreased since then. It disrupts the water cycle (vegetation and humus store and distribute moisture) and reduces biodiversity by destroying the habitat of millions of plant and animal species. In addition, soil compaction, trampled by livestock, prevents water infiltration and causes runoff that erodes the soil and deprives the last plants of water, rendering the land unusable.

Pastures and carbon sinks : The french example

The issue of carbon storage by grasslands for livestock production is complex and cannot be decided in a simple paragraph. This storage depends on many factors: climatic conditions, soil composition, age of the grassland, grazing intensity, etc. Depending on the case, grasslands can store less, as much or more carbon than forests. This carbon storage can partially compensate for livestock emissions due to enteric fermentation and animal excrement. Moreover, the use of grasslands only concerns the rearing of ruminants, which are often fed with cereals and cake in addition to grass.

Livestock farming can have a lower environmental impact thanks to grasslands, but it should not be forgotten that its yield per hectare is very low: on average 1.5 large cattle are raised at 600 kg per hectare... (Agreste, 2006) Knowing that edible meat represents about 37% of a cow's weight, we would have a productivity of 333 kg per hectare. (Interbev, By way of comparison, one hectare of crop land in France produces 3 tons of soya (FAOstat, 2017), which contains 50% more protein than beef (Anses Table Ciqual, 2016). While the use of non-arable land for grazing may be advantageous, it is clear that it is not a solution for feeding a growing population.

Fighting Global Warming Through Food

The 5th IPCC report (IPCC 2014, chapter 11), using calculations by Stehfest and al (2009), estimates that the simple application of the nutritional recommendations of the Harvard Medical School, which advise limiting the average consumption of ruminant meat to 10 g per day and the consumption of other meat, fish and eggs to 80 g per day, would reduce GHG emissions from agriculture by 36% and total emissions by more than 8.5%. This measure would be as effective as halving the world's total road traffic.

Not exceeding 450 ppm carbon equivalent in the 21st century will require a significant reduction in GHG emissions, at an estimated cost of 2.5% of global GDP in 2050. Compared to the scenario based on current trends, reducing meat consumption according to the recommendations of the Harvard Medical School would reduce this cost by 50%.

A British study (Scarborough et al., 2014) estimated that vegans emit 2.5 times less GHGs in their diet than omnivores (consuming 100 g of meat per day or more).

The weight of consumption choices was confirmed in a study published in May 2018 in the journal Science (Poore et al., 2018). Based on data from 38,000 farms in 119 countries worldwide, the study established the average environmental impact of the production of 40 of the main foods consumed, according to 5 indicators, including GHG emissions and annual area occupied.

A scenario replacing the current diet with a 100% plant-based diet would reduce diet-related GHG emissions by 49% and would require 76% less land. This represents 3.3 billion hectares, an area equivalent to the sum of the USA, China, Australia and the European Union.

The authors also studied a second scenario, in which half of the animal products would be replaced by plant equivalents. This scenario would reduce GHG emissions by 36% and would require 51% less land area.

These results confirm that to meet the urgent need to reduce our GHG emissions, the vegetalisation of food is an effective response.

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