Writing in the Proceedings of the National Academy of Sciences (PNAS) the team behind the study said that empowering consumers to make choices that help to reduce the impact of livestock and meat production on the environment through ‘devising and disseminating numerically sound information’ is priority.
“Unfortunately, currently available knowledge is incomplete and hampered by reliance on divergent methodologies that afford no general comparison of relative impacts of animal-based products,” noted the team – led by Professor Gidon Eshel of Bard College,USA.
“To overcome these hurdles, we introduce a methodology that facilitates such a comparison. We show that minimizing beef consumption mitigates the environmental costs of diet most effectively.”
Indeed, by comparing the environmental impacts and costs of a variety of meat and animal products the team reported that the environment inputs required for beef production shw that beef cattle need 28 times more land and 11 times more irrigation water than pork, poultry, eggs or dairy.
The team developed a new ‘uniform methodology’ that they were then able to apply to all five livestock categories and to four measures of environmental performance. From this they calculated that the amount of resources required for all the feed consumed by edible livestock and worked out the amount of hay, silage and concentrates such as soybeans required by the different species to put on a kilo of weight. They also included greenhouse gas emissions, not just from the production of feed for animals, but from their digestion and manure.
Independent of its effects on land and water, beef cattle release five times more greenhouse gas and consume six times more nitrogen than eggs or poultry, the team said – noting that as a result beef is the food animal with the biggest environmental impact.
While it has long been known that beef has a greater environmental impact than other meats, the authors of the paper say the current research is the first to quantify the scale in a comparative way.
"One can reasonably be an environmentally mindful eater, designing one's diet with its environmental impact in mind, while not resorting to exclusive reliance on plant food sources," Eshel recently told the BBC.
"In fact, eliminating beef, and replacing it with relatively efficiency animal-based alternatives such as eggs, can achieve an environmental improvement comparable to switching to plant food source."
Professor Mark Sutton, from the UK's Centre for Ecology and Hydrology, also told the BBC that while the findings from the current study come from US data, there the implications are similar for Europe.
"Although the exact numbers will be different for Europe (expecting a larger role of dairy), the overall message will be similar: Cattle dominate the livestock footprint of both Europe and US,” he said.
Reducing consumption: Taxes and new ways to eat
Last year Swedish agricultural authorities recommended an EU-wide tax to reduce meat consumption. Sweden’s Board of Agriculture said the levy would reduce the environmental impact of meat production. Instead, Europe's populations should eat more vegetables for both environmental and health benefits, it said.
The high environmental cost of beef production has also been cited as one of the main driving factors behind efforts to create lab grown meat. Last year Professor Mark Post and his colleagues in the Netherlands produced the world’s first burger made from ‘cultured beef’.
The proof of principle burger was used to demonstrate that it is technically possible to use stem cells isolated from cows to grow meat in a lab. The small strands of meat could then be used in the production of foods that use ground or minced beef, say the researchers behind the project.