8.3 What are the environmental issues associated with milk and dairy?
8.3.1 Livestock production contributes significantly to GHG emissions.
GHG contributions from livestock systems
Gerber, et al. (2013)
Livestock contribute 14.5% of human-made GHG emissions. Of this 14.5%:
Within the livestock sector, almost all GHG emission contributions come from enteric fermentation (methane emissions), manure (both methane and nitrous oxides), animal feed production (carbon dioxide and some methane), and from land-use change (carbon dioxide emissions from land clearing).
The % contribution from post-production emissions is very small for livestock – in this case they are CO₂ emissions related to the processing and transportation of livestock product between the production and retail point.
For more on the contribution of food systems to GHG emissions, see Chapter 3.
Focus on livestock – aggregate global emissions by species
Gerber, et al. (2013)
Globally, beef and dairy cattle contribute the highest GHGs, being ruminants and farmed in high numbers. Other ruminants (for example buffalo, sheep and goats) contribute less overall due to lower production numbers.
Non-ruminants such as pigs and chickens contribute less than cattle mainly because they do not emit as much methane from enteric fermentation, and convert feed into meat more efficiently, so the GHG emissions from pork and poultry production are lower, despite their being farmed in large numbers.
8.3.2 Carbon sequestration has been proposed to counter this.
Ruminant emissions are high but it has been argued that these are countered by their role in sequestering soil carbon
Advocates of grass-fed beef systems argue that well managed grazing livestock can help sequester carbon in soils.
It is claimed that this sequestration can partly or entirely outweigh the methane and nitrous oxide the animals emit; potentially grazing livestock systems can even be ‘emission negative.
If sequestration is assumed the carbon footprint of beef can shift from very high to very low
But caution is needed when it comes to livestock and sequestration
- This is still an under researched area and the evidence base is still uncertain.
- Carbon sinks are temporary, while ongoing livestock production will continue to produce methane and nitrous oxide.
- The extent to which sequestration occurs depends on: the status of the soil carbon levels before any management change, the baseline soil type and conditions, specific management techniques, climate, rainfall etc. – and many of these factors can change.
- Also need to consider: reversibility (grassland can be ploughed up) and saturation (after some decades soils approach carbon equilibrium; methane and nitrous oxide emissions will then always outweigh the sequestration); impacts on biodiversity can be mixed and may be negative.
- What is clear is that grasslands are major carbon stores – so it is important not to plough them up.
- Some grasslands are home to unique flora and fauna and grazing livestock may have historically contributed to this. But other grazing lands contain very little biodiversity.
- Poor grazing management can contribute to soil carbon losses while grazing livestock have historically (although less so now) been an important driver of deforestation.
8.3.3 Consumption and associated production of animal products is projected to increase globally.
Overall consumption and production of meat is projected to nearly double by 2050 under a business as usual scenario
Alexandratos and Bruinsma (2012)
Based on current trajectories, with rising incomes in developing countries and food consumption per capita and absolute population growth, total food consumption is projected to rise significantly. Meat consumption is expected to nearly double by 2050.
In developed countries, meat consumption is not expected to rise much further, if at all. The majority of the increase would be in developing countries, where significant income rises and population growth are expected. Population growth in Sub-Saharan Africa is projected to nearly double, from 730 million in 2006 to 1.68 billion in 2050.
The importance for food-related GHG emissions comes from the high GHG-intensity of meat production (see Chapter 3 for a review of this topic).
Consumption of meat and dairy products per capita is expected to rise
Alexandratos and Bruinsma (2012)
Per capita consumption of animal products (meat and dairy) is projected to rise mainly because of increased demand in developing countries, made possible by increases in average incomes.
But there is significant variation between and within regions
- Meat consumption has grown at 2.6% per year since 1981.
- But the aggregate picture masks strong regional variations.
- Consumption of meat has been growing at 4.9% annually in developing countries since 1981, with the per capita average increasing between 14 to 28 kg per year.
- But annual growth rate is only 3.3% if China and Brazil are excluded from the developing country totals.
- Currently Brazil and China account for 56% of developing country meat consumption but constitute only 28% of the developing country population.
- Consumption of animal products in Sub Saharan Africa has stagnated and in some countries has actually fallen.
- Consumption in developed countries has risen very little, since per capita intakes are already high.