Environmental vegetarianism

[2][a] As a result, significant reduction in meat consumption has been advocated by, among others, the Intergovernmental Panel on Climate Change in their 2019 special report[3] and as part of the 2017 World Scientists' Warning to Humanity.

[4][5] Other than climate change, the livestock industry is the primary driver behind biodiversity loss and deforestation and is significantly relevant to environmental concerns such as water and land use, pollution, and unsustainability.

[11] The FAO report estimates that the livestock (including poultry) sector (which provides draft animal power, leather, wool, milk, eggs, fertilizer, pharmaceuticals, etc., in addition to meat) contributes about 18 percent of global GHG emissions expressed as 100-year CO2 equivalents.

[b] This estimate was based on life-cycle analysis, including feed production, land use changes, etc., and used GWP (global warming potential) of 23 for methane and 296 for nitrous oxide, to convert emissions of these gases to 100-year CO2 equivalents.

A 2009 study by the Worldwatch Institute argued that the FAO's report had underestimated impacts related to methane, land use and respiration, placing livestock at 51% of total global emissions.

As populations grow, lowering meat consumption worldwide will allow more efficient use of declining per capita land and water resources, while at the same time making grain more affordable to the world's chronically hungry.

A 2018 report published in PNAS asserted that farmers in the United States could sustain more than twice as many people than they do currently if they abandoned rearing farm animals for human consumption and instead focused on growing plants.

[32] In November 2019, a warning on the "climate emergency" from over 11,000 scientists from over 100 countries said that "eating mostly plant-based foods while reducing the global consumption of animal products, especially ruminant livestock, can improve human health and significantly lower GHG emissions (including methane in the “Short-lived pollutants” step)."

The warning also says it this will "free up croplands for growing much-needed human plant food instead of livestock feed, while releasing some grazing land to support natural climate solutions.

[42] A 2022 study found that for high-income nations alone 100 billion tons of carbon dioxide could be removed from the air by the end of the century through a shift to plant-based diets and re-wilding of farmlands.

Paul Fischbeck, Michelle Tom, and Chris Hendrickson, researchers in civil and environmental engineering at Carnegie Mellon University, investigated the impact of America's obesity crisis on the environment by analyzing the food supply chain's resource usage.

The study offers a nuanced exploration into the environmental impact of dietary choices, specifically contrasting the perceived benefits of vegetarian and USDA-recommended "healthier" diets against their ecological footprints.

All types of meat but especially lamb and beef generate several times more greenhouse gas emissions in their production than plant-based foods. [ 1 ]
Box plot showing average GHG emissions for different food types and ranges
The amount of globally needed agricultural land would be reduced by almost half if no beef or mutton would be eaten. [ 15 ]
A small list of the benefits of a vegan/vegetarian diet on ones health
People in developed countries consume a substantially larger proportion of meat than those in developing countries . [ 25 ]