Here are the top 10 things to think about when considering the effect of food on the environment:

1. Humans and their livestock now constitute over 95% of all the large animal biomass on the planet.
Vaclav Smil, Harvesting the Biosphere: What We Have Taken from Nature (The MIT Press, 2013), p. 228, table 12.2.
Y. M. Bar-On et al., “The biomass distribution on Earth,” PNAS, June 19, 2018, 115(25): 6506–6511.

2. Livestock biomass today is greater than the TOTAL biomass of ALL other large animals on the planet (including humans) at any time during the last 100,000 years.
“Megafauna biomass tradeoff as a driver of Quaternary and future extinctions,” Anthony D. Barnosky, Proceedings of the National Academy of Sciences [PNAS], August 12, 2008, vol. 105 no. Supplement 1.

3. Livestock agriculture accounts for 51% of all worldwide greenhouse gas emissions.
Goodland, Robert & Anhang, Jeff. “Livestock and Climate Change,” WorldWatch, November/December 2009.

4. Greenhouse gas emissions for agriculture are projected to increase 80% by 2050.
Tilman, David & Clark, Michael. “Global diets link environmental sustainability and human health“. Nature. Vol. 515. 27 November 2014.

5. Soil, the basis of our human food supply, is eroding at a rate 10–20 times faster than the natural rate of soil formation in the United States and Europe. (Elsewhere in the world, soil erosion is even worse.)
David Pimentel and Michael Burgess, “Soil Erosion Threatens Food Production,” Agriculture 2013, 3(3): 443-463.

6. Water requirements for animal foods are much, much greater than for plant foods.
D. Pimentel et al., “Water Resources: Agricultural and Environmental Issues,” BioScience 54(10), September 2004.
“Water.” Environmental Working Group, 2011.
“Food Facts: How Much Water Does it Take to Produce…?” Water Education Foundation.
Hoekstra, Arjen Y. “The water footprint of food,” 2008.
“Water footprint of crop and animal products: a comparison.” Water Footprint Network.

7. Up to 2.7 trillion ocean animals are killed each year by humans; fish currently eaten could disappear from the oceans entirely by 2048.
Mood, A. and Brooke, P. “Estimating the Number of Fish Caught in Global Fishing Each Year,” July 2010.
“Fish count estimates.”
Worm, Boris, et al. “Impacts of Biodiversity Loss on Ocean Ecosystem Services“. Science 314(3), 3 November 2006.
Roach, John. “Seafood May Be Gone by 2048, Study Says“. National Geographic News, November 2, 2006

8. More than 70 billion animals are killed annually for food worldwide.
“Strategic Plan 2013-2017: For Kinder, Fairer Farming Worldwide“. Compassion in World Farming

9. 91% of Amazon destruction is caused by animal farming.
Margulis, Sergio. “Causes of Deforestation of the Brazilian Amazon“. World Bank Working Paper No. 22. 2003
More information on the Amazon and livestock:
Tabuchi, Hiroko, Rigny, Claire & White, Jeremy. “Amazon Deforestation, Once Tamed, Comes Roaring Back,” New York Times, February 24, 2017
Bellantonio, Marisa, et al. “The Ultimate Mystery Meat: Exposing the Secrets Behind Burger King and Global Meat Production.” Mighty Earth.

10. 80% of edible protein fed to poultry, and 90% fed to pigs, is wasted.
Vaclav Smil, Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation of World Food Production (MIT Press, 2001), p. 165, Figure 8.4.

More resources:
Eat for the Planet, by Nil Zacharias and Gene Stone (Abrams, 2018). This short, non-technical book clearly explains the impact of food on the environment.

All links in this post accessed on June 15, 2019.