More than half of methane released each year comes from human activities, notably farming. (July 2007) The Journal of Animal Science says that ruminant animals produce between 250 and 500 liters of methane gas every day. The combined environmental effect of the world’s livestock is enormous. There are around 1.5 billion cattle on our planet - more than double the number 30 years ago. Normally a cow's stomach is pretty inefficient - 80% of food ingested comes out as waste or methane. There are also over a billion sheep and some 800 million goats. Animal agriculture produces more than 100 million tons of methane a year and many organizations urge a vegetarian diet to help avert climate catastrophe. Changing the ruminants' diets is another approach. A trial in Scotland on lamb recently obtained a 70% decrease in methane formation, while in New Zealand, where agriculture accounts for almost 50% of the country's greenhouse gas emissions, scientists are working on reducing methane by getting rid of the microbes in animals' stomachs that produce methane. link

Large-scale meat production also has serious implications for the world’s climate. Animal waste releases methane and nitrous oxide, greenhouse gases that are 25 and 300 times more potent than carbon dioxide, respectively. Global meat production and consumption have increased rapidly in recent decades, with harmful effects on the environment and public health as well as on the economy, according to research done by Worldwatch Institute’s Nourishing the Planet project for Vital Signs Online. Worldwide meat production has tripled over the last four decades and increased 20% in just the last 10 years. Meanwhile, industrial countries are consuming growing amounts of meat, nearly double the quantity in developing countries. link


Latest news: 

Nov. 29 2017:  Getting a better handle on methane emissions from livestock. Cattle, swine and poultry contribute a hefty portion to the average American's diet, but raising all this livestock comes at a cost to the environment: The industry produces a lot of methane, a potent greenhouse gas. Just how much gas the animals release, however, is the subject of debate According to the U.S. EPA, the livestock industry is the second-biggest methane emitter in the U.S. Current estimates of total livestock methane emissions may rely on outdated emission factors and do not fully consider feed intake and differences in animal diets, or the facilities used to store manure. These data gaps lead to large uncertainties in methane emission figures. link



  • Agriculture link to greenhouse gases
  • Meat consumption globally
  • Grass-fed debate
Agriculture link to greenhouse gases

September 2017: Factory farming is killing the planet. Industrial agriculture is one of the most unsustainable practices of modern civilization. From start to finish, factory farming is responsible for the abuse of land, animals, and natural resources all for the express purpose of providing cheap, unhealthy food to the large amounts of people. Industrial agriculture only really crept its way into normative American culture in the 1970s but in just four decades, it has spread like a disease across the globe. Our current global food system is responsible for one-third of global greenhouse gases, while dependent on fossil fuels for transportation and synthetic fertilizers and pesticides. link

Grazing can fight desertification and reverse climate change
Allan Savory TED talk on holistic farming to sequester carbo - link

Response from George Monbiot (August 2014)  “(Savory’s) statements are not supported by empirical evidence and experimental work, and that in crucial respects his techniques do more harm than good.  link

November 2006. According to a new report published by the United Nations Food and Agriculture Organization, the livestock sector generates 18% more greenhouse gas emissions as measured in CO2 equivalent than transport. It is also a major source of land and water degradation.  link   The number one source of methane worldwide is animal agriculture. On a global basis, according to the FAO livestock is responsible for some 18% of all greenhouse gases emitted. Methane is the most important greenhouse gas on a dairy farm. The FAO estimates that about 52% of all greenhouse gases from the dairy sector is in the form of methane. link  

October 2017: The last argument for farming anilmals has collaped. The answer, we are told, is to keep livestock outdoors: eat free-range beef or lamb, not battery pork. But all this does is to swap one disaster – mass cruelty – for another: mass destruction. Almost all forms of animal farming cause environmental damage, but none more so than keeping them outdoors. The reason is inefficiency. Grazing is not just slightly inefficient, it is stupendously wasteful. Roughly twice as much of the world’s surface is used for grazing as for growing crops, yet animals fed entirely on pasture produce just one gram out of 81 grams of protein consumed per person per day. link

April 2009: Which meat harms our planet the least? As a general rule, red meat (beef, lamb, goat, and bison) are the worst offenders.  link

November 2013: Emissions of methane in U.S. exceed estimates. Cattle may be a bigger problem than US government thought. The nearly 90 million cattle in US feedlots are the country's largest source of methane from anthropogenic (human-caused) emissions according to the EPA. A new report published by Harvard University scientists estimate they may release 50% more methane into the atmosphere than the government had estimated. The new report finds that ruminant animals generate twice as much methane as the EPA supposed. The report comes on the heels of a decision by the EPA to reduce its estimates – by 25 to 30% – of the atmospheric carbon released by the natural-gas industry. link

December 2013: New survey shows cattle are the biggest source of greenhouse gases, accounting for more than three-quarters of all emissions from global livestock. link)  [Cows’ belching and farting is known as “enteric fermentation”] 

There is a counter argument
Don't blame dairy cows for greenhouse gas emissions - new study
Eating less meat and dairy products won't have major impact on global warming, expert argues. Read here

Meat consumption globally

Over the past 50 years, global meat production has almost quadrupled from 78 million tonnes in 1963 to a current total of 308 million tonnes per year. In 2014, around 315 million tonnes of meat were produced worldwide. For 2015, the FAO forecasts an increase to 318.8 million tonnes. The IAASTD predicts that this trend will continue, especially because the growing urban middle classes in China and other emerging economies will adapt to the so-called western diet of people in North America and Europe with its burgers and steaks. On average, every person on Earth currently consumes 42.9 kilograms of meat per year. In the EU, meat consumption has stagnated recently; there is also a growing number of vegetarians and vegans. What’s more, they main type of meat consumed has switched from beef to poultry. The favourite meat of the average European however is pork. The Chinese also share this appetite for pork. Per capita, meat consumption in China has increased six-fold over the past 40 years. Since the population almost doubled to 1.3 billion people over the same period, global demand for meat. link

Fermentation process:
Enteric fermentation is fermentation that takes place in the digestive systems of animals. In particular, ruminant animals (cattle, buffalo, sheep, goats, and camels) have a large "fore-stomach," or rumen, within which microbial fermentation breaks down food into soluble products that can be utilized by the animal. The microbial fermentation that occurs in the rumen enables ruminant animals to digest coarse plant material that monogastric animals cannot digest. Methane is produced in the rumen by bacteria as a by-product of the fermentation process. This CH4 is exhaled or belched by the animal and accounts for the majority of emissions from ruminants. Methane also is produced in the large intestines of ruminants and is expelled. There are a variety of factors that affect CH4 production in ruminant animals, such as: the physical and chemical characteristics of the feed, the feeding level and schedule, the use of feed additives to promote production efficiency, and the activity and health of the animal. It has also been suggested that there may be genetic factors that affect CH4 production. Of these factors, the feed characteristics and feed rate have the most influence. link

March 2016: Eat less meat to avoid dangerous global warming.  link

Grass-fed debate

October 2017: Eating grass-fed beef isn’t climate-friendly.
Ruminants contribute 80% of total livestock emissions.
To meet the growing demand for protein from grass-fed animals, a new report said, "we would have to massively expand grazing land into forest and intensify existing grassland through the use of nutrient inputs, which among other things, would cause devastating CO2 releases and increases in methane and nitrous oxide emissions," both potent climate-warming gases. link

Is grass-fed beef worse for the environment than grain-fed beef?  link  
June 2017:
Grass-fed beef tends to require more land and emit more GHGs than grain-fed beef - link

The debate is still open
. (February 2013)  Water consumption, methane gas emissions, the impacts of growing grain for feed, transportation impacts, air and water quality impacts from feed lots … the list goes on. Washington State University researcher Judith Capper found that feeding cattle grain on feed lots uses less land than feeding them only grass. It shortens the amount of time it takes to raise cattle to market weight, which means each cow requires less water and produces less methane. She also found that grain-fed cattle produce a third less methane than grass-fed because of how they digest the different feeds, a finding that is backed up by an Australian study. The studies, however, have been challenged - grass-fed cattle help sequester carbon in pasture, and that the impacts to water and air quality are worse on feed lots. The Environmental Working Group concludes, after a lifecycle analysis of beef and other meats, that grass fed beef is better for the environment. link  

How to reduce emissions

People have been eating insects for centuries, and up to 80 percent of the world outside Europe and North America still rely on insects for some part of their diet, it says. "Insects are one important solution as they offer a rich source of protein, amino acids, fatty acids and micronutrients," said Giulia Muir, an FAO expert on edible insects. link

September 2013: Better farming methods can reduce emissions by 30%. link 

(July 2008) Researchers in Argentina, which has more than 55 million cows, discovered methane from cows accounts for more than 30% of the country's total greenhouse emissions. Guillermo Berra, a researcher at the National Institute of Agricultural Technology, said every cow produces between 800 to 1,000 litres of emissions every day. Scientists are now carrying out trials of new diets designed to improve cows' digestion and hopefully reduce global warming. Silvia Valtorta, of the National Council of Scientific and Technical Investigations, said that by feeding cows clover and alfalfa instead of grain "you can reduce methane emissions by 25%".  link

December 2013: New survey shows cattle are the biggest source of greenhouse gases, accounting for more than three-quarters of all emissions from global livestock. link)  [Cows’ belching and farting is known as “enteric fermentation”] 

November 2009: Australian scientists are hoping to breed sheep that burp less as part of efforts to tackle climate change - about 16% of Australia's greenhouse emissions come from agriculture and 90% of the methane that sheep and cattle and goats produce comes from the rumen, and that's burped out. link

Eat kangaroo to 'save the planet'...
Kangaroos could be good for the planet. Kangaroos produce virtually no methane because their digestive systems are different. BBC    
A sustainable quota of 15-20% of the 30-50 million kangaroos is harvested each year. 70% of kangaroo meat (high in protein and low in fat) is exported, mainly to W. Europe. It is produced only from free ranging wild animals and is not farmed.
Objections to the harvesting, or culling, comes in a study from Sydney University - link

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