People will have to cut meat from their diets if the world is to stay within safer limits of planet-warming greenhouse gases, nitrate pollution and habitat destruction, according to a journal article published on October 04.
Experts agree that eating plant products can be better for the environment, because eating meat involves consuming animals which are themselves raised on plants, a less efficient process.
But there is some controversy about just how far people should shun meat for vegetables and grains to curb damage to the environment, partly because of wide disagreement about exactly what those impacts are.
Paper used coarse estimates to argue that, on current trends, livestock farming on its own - disregarding all other human activity - would push the world near danger levels for climate change and habitat destruction by mid-century.
The paper described "a profound disconnect between the anticipated scale of potential environmental impacts associated with projected livestock production levels and even the most optimistic mitigation strategies."
Solutions to the problem included using best practice such as substituting manure for nitrogen fertilisers, and increasing agricultural productivity, said the paper published in the Proceedings of the National Academy of Sciences.