I've spent half a century (yikes) writing for radio and print—mostly print. I hope to be still tapping the keys as I take my last breath.
While carbon-dioxide is the major greenhouse gas by volume, methane is more potent and its release is still rising; rising rapidly in fact. Scientists have calculated that over the next century the global-warming potential of methane is 28 times higher than for carbon dioxide.
About 30 percent of methane emissions come from fossil fuel burning, and close behind as a source (27 percent) is livestock farming.
What’s Your Impact.org explains: “Animals like cows, sheep, and goats are examples of ruminant animals. During their normal digestion process they create large amounts of methane. Enteric fermentation occurs because of microorganisms in the stomachs of these animals. This creates methane as a by-product that is either exhaled by the animal or released via flatus.”
To put this into farmyard language, the animals belch and fart methane; very large quantities of it.
More Cattle, More Gas
According to a 2006 article in Nature magazine, raising cattle, pigs, and other animals destined for the dinner table creates 90 million tonnes of methane each year. But now, it seems that estimate may be understating the problem.
Here’s The Guardian (September 2017) “Revised calculations of methane produced per head of cattle show that global livestock emissions in 2011 were 11 percent higher than estimates based on data from the UN’s Intergovernmental Panel for Climate Change.” The concentration of methane in the atmosphere has risen 10 times faster in the last decade than in previous decades.
The meat industry has grown a lot since the 1960s; beef production, for example, has doubled in the last 50 years. This is because the world’s population has grown from three billion in 1960 to 7.6 billion today. At the same time, people have become more affluent so they are able to add more meat to their diets.
Methane emissions are rising in Africa, Asia, and Latin America. At the same time, people in highly developed Western nations are eating less meat, so methane emissions are declining in Europe and North America.
A fully grown, barbecue-ready steer is going to tip the scales at about 635 kg (1,400 pounds). He’s going to let rip about 100 kg of methane a year. Plus, there are about 1.5 billion cattle in the world. Give or take, that’s about 150 million tonnes of methane annually.
And, then there are termites. What they lack in size they make up for in numbers.
There are more than 3,000 species of termite and they are industrious little critters. Many of the species eat decaying trees and other plants and produce methane in their digestive systems in much the same way as cows do.
At about 25 mm in length, a single termite emits about half a microgram of methane per day. That doesn’t sound like much, but the total numbers are immense. A British research team has studied termites in the tropical forests of Cameroon in Africa. It estimates the jungle is home to about 100 million termites per hectare.
There is some debate about the total termite methane gas emissions, but 20 million tonnes annually seems to be a frequently mentioned estimate.
Who Else Is to Blame?
There’s another methane emitter that should not be overlooked – flatulent humans.
Output depends on input; a high-fibre diet creates more gas that a low fibre one.
Here’s how molecular biologist Brian Farley explains how high- and low-fibre participants created methane in a study published in the British Medical Journal: “Assuming that these people and this diet are representative of the world population (not necessarily true, but close enough), human beings collectively release about 73 metric tons of methane and 1,000 metric tons of carbon dioxide into the atmosphere every day just by farting.”
Plant-Based Meat Produces no Methane
Recently, products have come onto the market that could lead to a reduction in livestock-generated methane. Damian Carrington in The Guardian (November 2017) has written about meat “… food that looks and tastes just as good as meat or dairy products [that are] made from plants.”
He adds that “meat and dairy companies are now piling in with investments and acquisitions …” The government of China has put $300 million into companies in Israel that are making meat grown in laboratories. Bio-meat, as it’s called, is grown from animal cells.
Milk made from soya, almonds, and other sources is already well established and accounts for about 10 percent of milk sales in the United States.
Billionaire Richard Branson is investing in the technology. He says, “I believe that in 30 years or so we will no longer need to kill any animals and that all meat will either be [lab-] or plant-based, taste the same, and also be much healthier for everyone.”
And, the gigantic loads of smelly gas won’t be rising from feed lots and barns.
While fossil-fuel burning and raising livestock are the biggest sources of methane, there are other contributors:
- Rotting waste in landfills – 16 percent of human-source methane.
- Burning organic material such as forestry and crop waste – 11 percent.
- Rice farming – nine percent.
- Burning biofuels – four percent.
In addition, there are natural sources of methane such as wetlands, and oceans. However, these sources of methane have remained stable for thousands of years. It’s human activity over the last 250 years or so that has bumped up the emissions.
There are vast quantities of methane locked in the Arctic permafrost. Scientists are concerned that global warming might thaw the frozen ground and release what some are calling a methane time bomb. Michaeleen Doucleff at National Public Radio writes that “No one knows exactly how big the bomb is. It may even be a dud that barely detonates.”
Natural gas is primarily methane with small amounts of nitrogen, hydrogen sulphide, carbon dioxide, and helium.
- “The Seven Megatrends That Could Beat Global Warming: ‘There Is Reason for Hope.’ ” Damian Carrington, The Guardian, November 8, 2017.
- “Main Sources of Methane Emissions.” Whatsyourimpact.org, undated.
- “Methane Emissions From Cattle Are 11% Higher Than Estimated.” Agence France-Presse, September 29, 2017.
- “Do Human Farts Contribute to Global Warming?” Brian Farley, Quora, April 22, 2015.
- “Is There a Ticking Time Bomb Under the Arctic?” Michaeleen Doucleff, National Public Radio,January 24, 2018.
© 2018 Rupert Taylor
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