This article was originally written in 2009 and has been updated in 2017, with conditions in 2017 far worse than in 2009.
Synopsis: The world is rapidly approaching an unprecedented catastrophe from global climate change and other environmental threats, and a major societal shift to plant-based (vegan) diets is an essential part of the necessary responses to avoid that catastrophe. Since methane emitted by farmed animals is in the atmosphere for less than 20 years and is 72 to 105 times as potent as a greenhouse gas than carbon dioxide during that time, reducing the number of farmed animals would have a major, rapid effect in reducing climate change. A major shift to plant-centered diets would have many other benefits, including reducing diseases, hunger, water and energy shortages, rapid species extinction, water pollution, destruction of rainforests and other valuable habitats and soil erosion and depletion.
Global catastrophe or sustainable future? It will depend largely on our food choices!
It may seem naïve to argue that dietary shifts can make a major difference in responding to today’s many crises, but if he world stopped raising the current 70 billion farmed animals that are slaughtered annually worldwide, it would make a tremendous difference with regard to many, if not all, of today’s current problems. Let us consider how.
First, it is important to recognize that the world is rapidly heading toward an unprecedented catastrophe from global climate change and other environmental threats. There are almost weekly reports of severe droughts, heat waves, storms, flooding, wildfires and meltings of polar icecaps and glaciers.  In 2017 there were three category 4 or 5 hurricanes and a series of massive wildfires that caused major destruction in California, as well as many more severe climate changes in other areas.While these events have occurred due to an average temperature increase of about two degrees Fahrenheit in since the start of the industrial revolution, global climate scientists, including those with the Nobel Prize-winning UN Intergovernmental Panel on Climate Change (IPCC), are projecting an increase of up to to 11 degrees Fahrenheit in the next 100 years , which would have devastating effects on humanity and all of life on the planet.
And we are talking about threats that must be addressed very soon. Some climate scientists, including James Hansen, director of the National Aeronautics and Space Administration (NASA) Goddard Institute for Space Studies, are warning that global warming could reach an irreversible tipping point and spin out of control within a few years, with disastrous consequences, unless major changes soon occur.  Scientists at the February, 2009 annual meeting of the American Association for the Advancement of Science indicated that global warming will likely increase more rapidly than expected because greenhouse gas emissions (GHGs) have increased faster than recent predictions and increased temperatures are setting off positive feedback (self-reinforcing) mechanisms in global ecosystems.  2017 is projected to be the second or third warmest year since temperature records were kept worldwide in a880, following three consecutive years of worldwide temperature records.
There is increasing awareness of the need to make major changes in many phases of society to reduce global climate change. However, most lists of recommendations ignore or give little attention to the impact of our diets on GHGs. A landmark 2006 report by the United Nations Food and Agricultural Organization estimated that livestock production globally is responsible for more GHGs (in CO2 equivalents) than the world’s entire transportation sector combined .  The report, “Livestock’s Long Shadow,” also projects that the world’s current population of about 60 billion farmed animals will double in 50 years if human population growth and dietary trends continue.  The resulting increase in GHGs would largely negate reduced GHG emissions from improved efficiencies in transportation, electricity and other sectors and conservation steps, and make it extremely difficult, if not impossible, to reach the GHG reductions that climate experts think are essential to avoid a climate disaster. A2009 cover story in WorldWatch magazine, “Livestock and Climate Change,”concluded that the livestock sector is responsible for at least 51 percent of human induced GHGs.
Expert recognition of the importance of diet in preventing global warming is growing. In the Fall of 2008, Dr. Rajendra Pachauri, Chair of the IPCC, which shared a Nobel Peace Prize with Al Gore in 2008, called on people in the developed world to “give up meat for one day [a week] initially, and decrease [meat consumption] from there.”  More recently, James Hansen, perhaps the most prominent scientific advocate of aggressive action against global warming — told an interviewer:
“… if you eat further down on the food chain rather than animals, which have produced many greenhouse gases, and used much energy in the process of growing that meat, you can actually make a bigger contribution in that way than just about anything. So, that, in terms of individual action, is perhaps the best thing you can do.” 
The main reason that animal agriculture’s contribution is so great is that farmed animals, especially cattle and other ruminants, emit methane as part of their digestive processes (belching and farting) and methane is about 23 times as potent as CO2 in producing global warming, when standard 100 year periods are considered.  However, since most methane survives in the atmosphere for less than 20 years, if a 20 year period is considered, methane is 72 to 105 times as potent as CO2.  (While the 23 number is more commonly used, the higher range is far more meaningful, since the methane is not acting at all for at least 80 years of the 100 year standard period.) By contrast, most CO2 is in the atmosphere for hundreds of years and its impact is reduced by the predominantly cooling aerosols emitted by typical CO2 sources like smokestacks and tailpipes. 
Since methane contributes a significant amount of GHGs (in CO2 equivalents)  and since farmed animals and their manure are the major source of methane, and since methane is in the atmosphere for only a short time, a major societal shift to plant-based diets would have a substantial and rapid effect in reducing global climate change. Having major world leaders call for such a change, preferably after publicly announcing suitable changes in their own diets, could very dramatically increase awareness of the threats of climate change and the need for major dietary and other lifestyle changes. Such changes could provide some breathing space, during which other important changes could be made.
Additional factors that make switches to plant-based diets even more important are: (1) the production of animal products causes about nine percent of total CO2 emissions, from the production of pesticides and fertilizer, use of irrigation pumps, extensive refrigeration and other processes;  (2) nitrous oxides are emitted from animals’ manure and from chemical fertilizer used to grow feed crops and these gases are almost 300 times as potent as CO2 in producing warming;  (3) the burning of rainforests to create grazing land and land to grow feed crops for animals releases substantial CO2 and also destroys trees that would absorb CO2;  (4) because they feast on the charred remains of these trees, termites are perhaps the fastest growing animal species on the planet, and they also emit methane as part of their digestive processes. 
Major shifts to vegan diets would also provide substantial relief to many other threats to humanity:
* Widespread hunger is an increasingly important issue. A June 2009 UN Food and Agriculture report indicated that the number of chronically hungry people passed the one billion mark (almost one person in six) for the first time.  This hs since been reduced to about 800,000 in 2017. An estimated 20 million people, mostly children, die annually from hunger and its effects and many more suffer permanent physical or mental damage due to insufficient nutrition.  While more than enough grain is produced today to feed all of the world’s people , over 70 percent of the grain produced in the United States and almost 40 percent produced worldwide are fed to animals raised for slaughter.  The hunger situation is likely to become even more critical as world population continues to increase and droughts, reduced soil fertility due to higher temperatures, storms and other effects of global warming reduce food production. 
* It is projected that half of the world’s people will live in areas chronically short of water by 2050.  Some climate experts are projecting that the world is now in the “Century of Drought.”  Many US regions have experienced severe droughts for the past few years. According to California’s governor, the state’s drought has resulted in its wildfire season, which used to last a few months, now lasting almost all year round.  Major parts of Australia have experienced drought for ten years, and there are fears that this may become a permanent condition.  Israel is facing a four year drought, one so severe that the level in the Sea of Galilee has dropped to a level too low to have water pumped from it. 
The dietary connection is that it takes up to 13 times as much water per person for a typical animal-based diet than for a vegan diet.  The amount of water necessary to raise one steer to maturity would float a naval destroyer.  Also, as indicated above, animal-based agriculture contributes significantly to climate changewhich contributes to droughts and to the melting of glaciers and the reduced flow of rivers and streams and levels of lakes and ponds.
* A recent report by 11 retired US generals and admirals indicated that climate change is a multiplier effect for potential violence. They pointed out that there will be potentially tens of millions of desperate refugees fleeing droughts, wildfires, heat waves, storms, floods, and other conditions caused or worsened by global climate change, and this increases the potential for instability, violence, terrorism and war.  Several experts assert that a major factor behind the recent violence in Darfur is the severe drought that has afflicted the area and created many refugees. 
* Species of plants and animals are disappearing at what many experts consider the fastest rate in history. One major reason is the rapid destruction of tropical rainforests (where over half of the species of plants and animals live) at a very rapid rate to create pasture land and land to raise feed crops for animals. One study indicated an average of 55 square feet of rainforest are destroyed for every quarter pound hamburger patty produced and exported for consumption in a fast food market.  A recent report indicated that our oceans may be virtually free of fish by 2048, because huge trawlers put out very wide nets that capture all marine life in its area. 
* There is currently an epidemic of heart disease, various types of cancer and other chronic, degenerative diseases. Efforts to treat these diseases has resulted in soaring medical costs which have resulted in major deficits and other financial problems at national, state and local levels. These financial difficulties reduce money available for environmental protection and for many other essential services. Yet, there is little effort to inform people that well-balanced, nutritious vegan diets can prevent, alleviate and sometimes reverse diseases. Instead, there are major debates about how to end the current dysfunctional medical system, in which millions of people have no or inadequate medical insurance coverage.
* Many more examples of problems made worse by animal-based agriculture can be given related to such issues as the destruction of coral reefs, soil erosion and depletion, animal wastes polluting our waters and animal-initiated diseases such as swine flu.
In view of the above and more, the world’s people face a major choice. We can continue basically with current practices as the world continues on its increasingly rapid path to an unparalleled cataclysm. Or we can adopt healthy plant-based diets and other practices that can help shift our very imperiled world to a sustainable path. If we fail to act and soon, how will we explain our inaction to future generations?
1. See, for example, “Climate Change, Global risks, challenges & decisions,” Copenhagen 10-12 March, 2009, University of Copenhagen, Denmark, http://lyceum.anu.edu.au/wp-content/blogs/3/uploads//Synthesis%20Report%20Web.pdf
2. “Intergovernmental Panel on Climate Change (IPCC) Fourth
Assessment Report,” February, 2007. http://www.ipcc.ch/
3. James Hansen, “Tipping Point: Perspective of a Climatologist,” 2008=2009 State of the World, 6,
4. American Association for the Advancement of Science, February, 2009 annual conference, Public release, “Climate change likely to be more devastating than experts predicted, warns top IPCC scientist,”
5. FAO Newsroom, “Livestock a major threat to environment,” November 29. 2006,
7. Juliette Jowitt, “UN says eat less meat to curb global warming,” The Observer, September 7, 2008, http://www.guardian.co.uk/environment/2008/sep/07/food.foodanddrink
8. Be Veg! Go Green! Save the Planet, February 8, 2008, “Dr. James Hansen: “We have only four years left to act on climate change,” http://veg4planet.blogspot.com/2009/02/dr-james-hansenwe-have-only-four-years.html
9. Noam Mohr, “A New Global Warming Strategy:
How Environmentalists are Overlooking Vegetarianism as the Most Effective Tool Against Climate Change in Our Lifetimes,” Earthsave,
10. Supreme Master TV Video, “Methane __ 72 Times the Warming Potential of CO2,” June, 2009,
11. Same as #9
13. UN News Centre Report, “Rearing cattle produces more greenhouse gases than driving cars, UN report warns,
15. “Burning rainforests, melting tundra could accelerate global warming well beyond current projections.” mongabay.com, February 16, 2009
16. Greg Brockberg, “Termites as a Source of Atmospheric Methane,” http://www.iitap.iastate.edu/gcp/studentpapers/1996/atmoschem/brockberg.html
17. UN FAO Report, “1.02 billion people hungry; one sixth of humanity malnourished – more than ever before.” June 19, 2009, http://www.fao.org/news/story/en/item/20568/icode/
18. “Our Food, Our World,” Earthsave Foundation, 1992, p.6.
19. ”Eating up the World: the Environmental Consequences of Human Food Choices,” 16 page booklet, Vegetarian Network Victoria, 2009,
20. GoVeg.com, “Wasted Resources – Food,”
21. Paul Kedrosky, “Lester Brown on the Coming Food Crisis (Again), Infectious Greed, May 20, 2009, http://paul.kedrosky.com/archives/2009/05/lester_brown_on.html
22. Dan Vergano, “Water shortages will leave world in dire straits,” USA Today, January 26, 2003,
23. Michael McCarthy, “The Century of Drought
One third of the planet will be desert by the year 2100, say climate experts in the most dire warning yet of the effects of global warming,” CommonDreams.org, October 4, 2006,
24. Brad Johnson, The Wonk Room, “”Global Boiling: In California It’s ‘Fire Season All Year Round,’”
25. Kristin Underwood, “Australia’s Drought Worsens,” Treehugger, February 9, 2008,
Also: “Report: Climate Change 2009 – Faster Change and More Serious Risks,” Australian Government Department of Climate Change, July 9, 2009,
26. Jewish Telegraphic Agency Report, “Israel halts Sea of Galilee water pumping, January 22, 2009,
27. Tell Youth the Truth, “Animal Agriculture Equates to Wasted Resources and environmental Degradation,”
28. “The Browning of America,: Newsweek, February 22, 1981, p. 26.
29. John Timmer, ars technia, “Ex-military leaders call climate change a national security issue,” May 28, 2007,
30. Jacl Burton, “Climate Change as Catalyst for War: Can We Stop the World’s Water Crisis or Is Darfur Only the Beginning,” Suite 101.com,February 11, 2008,http://war-poverty.suite101.com/article.cfm/war_and_water
31. Crede Calhound, “Kids Can Help Save the Rainforest,” http://www.deepcreektimes.com/kids/march2005.html
32. John Roach, “Seafood May Be Gone by 2048, Study Says,” National Geographic News, November 2, 2006,