What do you imagine are the current, main causes of extinctions? You’d probably have a pretty accurate picture of bleak things like deforestation, climate change, and pollution (Fig. 1). However, you’d be forgiven for not knowing that four out of five of the main threats to biodiversity (1) have a direct link to human consumption of animal products: the livestock industry is behind much of habitat change, climate change, over-exploitation and nutrient pollution (2, 3).
Despite its key role, animal-product consumption isn’t made its own category in formal assessments of threats to biodiversity, like the Millennium Ecosystem Assessment, and it’s only apologetically mentioned by conservation charities like Greenpeace or the WWF.
Earth is home to perhaps 1.9 million described species, and up to 1 million years ago these creatures made up 99% of Earth’s biomass (the other 1% being us). Sometime around 10,000 years ago, most of us abandoned a nomadic, hunter-gatherer lifestyle in favour of farming. We were very good at this, and since then our population – and our appetite for animal products – has exploded. Through the process somewhat disingenuously known as “land-use change”, livestock farming and its feed now takes up 17,000km2, which is a full quarter of Earth’s available land (1). As a consequence, livestock now makes up 20% of the world’s biomass (2) (Fig. 2). Is there little wonder that there’s no room left for nature? Sadly, land-use change is probably the main threat to terrestrial biodiversity (1, 2). It now affects ~85% of the threatened birds, mammals and amphibians on the IUCN Red List, which keeps track of our most vulnerable species.
Of course, all consumption comes with a cost, meat or not: we burn oil to run the machinery that allows us to produce cereals on an industrial scale, and we fell rainforests to grow soya. These monocultures are plainly bad for biodiversity, but the majority of these crops do not end up on our plates (Fig. 3). Cattle, pigs and poultry now consume 50% of the world’s wheat, 80% of its maize and over 90% of its soya (3). Livestock and its feed make up 75% of all agricultural land. Much of this is grown in Brazil, at the expense of the Amazonian rainforest and cerrado (2, 3).
The impact of this massive land-use change echoes through the wastes of industrial animal and feedstock production, which cause nutrient pollution. Pesticides, herbicides, fertilisers, hormones, antibiotics and manure eventually make their way into freshwaters, and out to sea. Over 400 hypoxic “dead zones” have been recorded, many directly related to animal manure, and feedstock fertiliser (2).
Furthermore, land-use change for animal agriculture, such as felling carbon-sequestering forests, indirectly contributes to climate change. There’s also the direct contribution of rumination to GHGs (mainly through belching). Animal agriculture is estimated to be responsible for 14.5% of anthropogenic GHG emissions, equivalent to those from transportation (2).
Over-exploitation is clearly linked to marine biodiversity loss, where fish biomass (including those we eat, and those we kill accidentally) has reduced by 90% since the onset of industrial fishing. Indeed, 75% of the world’s fisheries are overexploited or depleted (1). Tropical vertebrates in Africa and Southeast Asia are particularly threatened by the lucrative bushmeat trade (2). Wild animals are often killed as they are perceived as a threat to the livestock industry, and persecution of apex predators has knock-on effects for the whole ecosystem, known as trophic cascades (2).
The future of food?
Industrialised factory farming, now standard in the West, is being exported to rapidly developing and biodiverse nations such as China as their citizens begin to enjoy a more affluent lifestyle. Increasing populations are likely to worsen the impact of meat-eating on biodiversity (2). What can be done?
Entomophagy – insect eating – may be a more ecologically sound way of getting protein. Already common in parts of the world like Thailand, companies like Grub are hoping these ecological credentials will help it to catch on in the West, too. Naturally, I jumped on the environmentalist bandwagon and tried them myself in the traditional way, in a stir-fry, post-hike, atop a Welsh mountain (Fig. 4). However, a recent study argued that crickets were no more protein efficient than chickens, due to the large effect of diet on cricket protein content (4).
Other hopefuls believe new and creative technologies can satiate our appetite for animal protein while protecting the planet. To quote Ester Boserup – “necessity is the mother of invention”. American company Hampton Creek, partly funded by Bill Gates, is developing a line of plant-based egg substitutes, which they claim have less environmental impact than regular eggs. Similarly, lab-grown beef has been tried and tasted, also claiming to reduce the environmental cost of meat-consumption (5) (Fig. 5).
Others claim that livestock is not intrinsically bad, but that the environmental problem is industrialised farming methods. For example, pigs and poultry are omnivores, traditionally fed on food waste over feedstock. Despite being intuitively biologically efficient (3), it has been banned by the EU since 2002, and subsequently protested by groups like The Pig Idea.
While the impact of animal product consumption on wildlife is becoming clearer to eco-conscious consumers in the West, the obvious answer – that we eat less, or no meat – is unlikely to be popular. The new UN Sustainable Development Goals aim to eliminate poverty and hunger, but as those lifted out of poverty start eating more meat, this will further threaten biodiversity conservation. For clearly defined problems and solutions, conservation scientists should lead the way, with food foremost on the menu.
- Millennium Ecosystem Assessment (2005) Ecosystems and Human Well-being: Biodiversity Synthesis. World Resources Institute, Washington, DC.
- Machinova, B., K.J. Feeley, and W.J. Ripple (2015) ‘Biodiversity conservation: The key is reducing meat consumption’, Science of the Total Environment, 536, pp. 419-431.
- Tudge, C. (2010) ‘How to raise livestock – and how not to’. In: D’Silva, J. and J. Webster (eds.) The Meat Crisis: Developing more Sustainable Production and Consumption. Earthscan: London, pp. 9-21.
- Lundy, M.E. and Parrella, M.P. (2015) ‘Crickets Are Not a Free Lunch: Protein Capture from Scalable Organic Side-Streams via High-Density Populations of Acheta domesticus. PLoS ONE, 10, 4, pp. 1-12.
- Tuomisto, H. L. and M. J. Teixeira de Mattos (2011) ‘Environmental Impacts of Cultured Meat Production’, Environmental Science and Technology, 45, 14, pp. 6617-6123.