A review of meat consumption, health and the environment published in Science on 20 July reported that the global consumption of meat is rising as the world’s population size grows and affluence increases. Data suggests that while meat consumption in some high income countries is plateauing or beginning to decline, it is increasing in many other countries, including those with large populations, such as China.
Increased meat consumption has major negative consequences for land and water use and environmental change. The most significant direct influence of meat production on biodiversity is through the conversion of land to agricultural use: natural habitats becoming grassland and arable land changing to the production grain and soya to feed livestock. This conversion of land to pasture and arable feed crops results in an increase in pollutants such as nitrogen and phosphorus which have a detrimental effect on biodiversity.
Agriculture uses more freshwater than any other human activity, with nearly a third required for livestock. Water used for growing animal feed accounts for 98% of the total water footprint of livestock production. Meat production in water-stressed areas is therefore a major competitor with other uses of water, including that required to maintain natural ecosystems.
The most important greenhouse gases caused by humans are carbon dioxide, methane, and nitrous oxide. Meat production results in the emissions of all three and is the single most important source of methane.
Professor Tim Key, co-author of the review said “What’s happening is a big concern and if meat consumption goes up further it’s going to be massively more so. On a broad level you can say that eating substantial amounts of meat is bad for the environment.”
Although meat provides a source of nutrients including protein and micronutrients such as iron, zinc and vitamin B12, high meat consumption has been linked to adverse health effects. The World Health Organization’s International Agency for Research on Cancer (IARC) classifies processed meat as carcinogenic to humans because of an association with colorectal cancer, and red meat as probably carcinogenic to humans, also based mainly on evidence of links to colorectal cancer.
The review concludes: “History suggests that change in dietary behaviours in response to interventions is slow. But social norms can and do change, and this process can be aided by the coordinated efforts of civil society, health organisations, and government. However, it is likely to require a good understanding of the impact of meat consumption on health and the environment and a license from society for a suite of interventions to stimulate change.”