Are Humans Becoming More Carnivorous? Environmental Impacts

In the previous post, we examined a new study by Bonhommeau et al. (2013) which revealed that global meat consumption has increased over the past five decades. How does an increase in meat consumption affect the environment?

Cows (photo from Living Green Magazine)

The livestock sector lies within the top two or three of the most important contributors to environmental issues, both locally and globally. Despite not being a major global economic player, the livestock sector is beneficial and crucial to society, employing and feeding growing global populations (Steinfeld et al., 2006; Herrero et al., 2009). Livestock agriculture contributes to environmental problems such as land degradation, land use change, climate change and greenhouse gas emissions, water shortage and pollution, nutrient excretion, loss of biodiversity, and competition for human food (Steinfeld et al., 2006; Janzen, 2011). These environmental impacts are driven by growing stresses on global human populations, namely the those of food, water, and energy security, biogeochemical interferences, and habitat (Janzen, 2011).

Let's now examine some of these impacts in a bit more detail. Many of the other impacts mentioned above will be the topics of future posts.

Land Use Change and Degradation

Land use refers to the ways in which land is used for human means. It is "characterised by the arrangements, activities and inputs that people undertake in a certain land cover type to produce change, or maintain it" (FAO, 2013). Land degradation refers to the reduction of resources as a result of processes which act on the land, including soil erosion, deterioration of the properties of the soil, and loss of natural vegetation (Steinfeld et al., 2006).

Deforestation for agriculture in Brazil's Pantanal wetland 
(from JNCC, 2013)

Livestock now represents the largest portion of human land use forms, affecting ecosystems around the world (Janzen, 2011). An example of environmental problems brought on by land use change for agriculture is the degradation of tropical rainforests, such as the Amazon. Two main phenomena are related to deforestation as a result of intensive raising of livestock, the first being the direct conversion of forest to pasture land and the second being the clearing of forest for crop growth to feed livestock (Herrero et al., 2009). Approximately 20-30% of the Earth's land surfaces are used for grazing, while approximately one third of cultivated land area is used to feed livestock (Janzen, 2011). 

GHG Emissions & Climate Change

Climate change is possibly the most pressing environmental challenge that has faced the planet. According to the IPCC (2013), the main authority on climate change, the "warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia". This warming can be seen in the atmosphere, the ocean, the cryosphere, in sea level, and in carbon and biogeochemical cycles. The largest contributor to total radiative forcing is caused by the increases in anthropogenic GHGs, such as CO2, since 1750.

Disintegrating iceberg near West Greenland
(from The Guardian)

Animal agriculture produces GHG emissions in the form of CH4 from enteric fermentation, N2O from fertiliser use, CH4 and N2O from manure management practices, and CO2 from from fossil fuel and energy use (O'Mara, 2011) and land use and its changes (Herrero et al., 2009). Livestock induced emissions account for 2.4 billion tonnes of CO2 per year, and on a life cycle analysis basis, they contribute up to 18% of global GHG emissions (Steinfeld et al., 2006). 

Water Shortage and Pollution

Water is essential for life. Only 3% of the water on Earth is fresh, and surface water only accounts for 0.3% of the total amount of freshwater (this includes lakes, rivers, and streams). Another 68.7% of all freshwater is locked away in glaciers, while 30% of freshwater is located within the pores of the ground in the form of groundwater (US EPA, 2013). Approximately 64% of the world's population is expected to live in water-stressed basins by 2025 (Steinfeld et al., 2006).

Water shortage in China (photo from The Guardian)

Freshwater is extensively used in livestock agriculture, the most significant use coming from the irrigation of crops for intensive feeding operations. The livestock sector is a key player in increasing water use and represents 8% of global human water use (Steinfeld et al., 2006). For instance, approximately 16,000L of water are needed to produce 1kg of beef (Janzen, 2011). In terms of water pollution, the major sources from the livestock sector include animal waste, antibiotics and hormones, chemicals from tanneries, fertilisers and pesticides for feedcrops, and sediments from eroded pastures. These pollutants contribute to freshwater eutrophication, coastal dead zones, and the degradation of coral reefs, among others (Steinfeld et al., 2006).

As I mentioned above, these are only some of the many environmental impacts of livestock agriculture. Livestock's Long Shadow by Steinfeld et al. is currently the most comprehensive study on the environmental impacts of the livestock sector. I strongly recommend flipping through it if you're eager to learn more on the topic.

Having read about some of the environmental impacts arising from the livestock sector, what do you think are potential solutions for a more sustainable food industry? 

Thanks for reading!