Solid scientific evidence contradicts a false, counterproductive claim 01/16/2020
Today's guest article is by Frank M. Mitloehner, Ph.D., Professor of Animal Science and Air Quality Extension Specialist, University of California, Davis. His article — which we’ve edited and expanded — comes to us courtesy of The Conversation.
Meat affects the environment, but cows are not killing the climate
By Frank M. Mitloehner, Ph.D.; Edited and expanded by Craig Weatherby
As the scale and impacts of climate change become increasingly alarming, meat is a popular target for action.
Many climate activists urge the public to eat less meat to save the environment, and some have called for taxing meat to reduce consumption.
Their key claim is that globally, meat production generates more greenhouse gases than the entire transportation sector.
However, this claim is demonstrably wrong — and its persistence has misled people about the links between meat and climate change.
Foregoing meat and meat products is not an environmental panacea and wide adoption of meat-abstinence could harm people’s health and livelihoods — especially the billions who rely on livestock for essential food, income, and fertilizer.
Setting the record straight on meat and greenhouse gases
A healthy portion of the bad rap on meat's climate impacts centers on the assertion that livestock is the largest source of greenhouse gases worldwide.
But, according to 2016 data from the U.S. Environmental Protection Agency, the largest sources of greenhouse gas (GHG) emissions in America were electricity production (28% of total emissions), transportation (28%) and industry (22%).
The EPA estimates that all agriculture — including plant and animal farming — account for 9% of GHG emissions, while all animal agriculture contributes only 3.9% of total U.S. greenhouse gas emissions.
So, what explains people's extreme misperceptions about livestock emissions?
The distortion started in 2006 when the United Nations Food and Agriculture Organization (FAO) published a widely publicized study titled “Livestock’s Long Shadow,” which estimated that livestock produced 18% of the world’s greenhouse gas emissions.
That estimate led the FAO to draw the startling conclusion — later retracted — that livestock raised to produce meat were warming the climate more than all modes of transportation combined.
(The FAO report was followed by an obviously flawed 2009 analysis by the Worldwatch Institute, which claimed that 51% of global GHG emissions come from rearing and processing livestock — a wildly implausible figure that's far higher than any other estimates.)
However, the FAO’s estimate and resulting conclusion were demonstrably wrong, and their estimate has since been corrected by Henning Steinfeld, the report’s senior author.
The problem was that the FAO's Steinfeld and his colleagues used a comprehensive life-cycle assessment to calculate the GHG emissions associated with livestock, but employed a different method to calculate the GHG emissions associated with transportation.
For livestock, they considered every factor associated with producing meat, including GHG emissions from animals (belching and manure), emissions from fertilizer production, and the GHG impacts of growing animal feed and converting land from forest to pasture.
In contrast, the FAO analysts only counted the GHG emissions from finished cars, trucks, trains, and planes, while ignoring the GHG emissions related to manufacturing their materials and parts, assembling them, and building and maintaining roads, bridges, railways, and airports.
As a result, the FAO’s erroneous comparison of transportation-related GHG emissions to livestock-related GHG emissions was a case of comparing apples to oranges.
Options for reducing GHG emissions from the livestock sector. Red bars show the potential range for each (Herrero et al. 2016).
I pointed out this flaw during a March 2010 speech to fellow scientists, which led to a flood of media coverage. To its credit, the FAO immediately owned up to its error.
Unfortunately, the agency’s initial claim that livestock was responsible for the lion’s share of world greenhouse gas emissions had already received wide coverage. To this day, we struggle to “un-ring” that misleading bell.
As the FAO’s Steinfeld has pointed out, the percentage of direct, worldwide GHG emissions from transportation and livestock can be compared:
- 14% of global GHG emissions comes from direct, fuel-related transportation emissions.
- 5% of global GHG emissions comes directly from livestock, mostly in the form of burps.
In its most recent lifecycle assessment report, the FAO estimated that all activities related to livestock and meat production produce 14.5% of global greenhouse gas emissions — but there’s no comparable life-cycle assessment for transportation, making fair comparisons impossible.
Importantly, the U.S. EPA estimates that — thanks to greater efficiencies compared with livestock production in developing countries — the percentage of direct GHG emissions from livestock in America is significantly lower, at about 3.9% of the total.
And changes to U.S. livestock practices have made production more efficient. According to the FAO, direct greenhouse gas emissions from U.S. livestock have declined 11.3% since 1961, while meat production has more than doubled.
Giving up meat won’t save the climate, and millions rely on livestock
Many people believe that skipping meat once a week will make a significant difference to the climate.
But our University of California research estimates that if all Americans skipped meat one day per week — a goal embodied in the “Meatless Monday” campaign — this would only reduce the nation’s GHG emissions by 0.5%, leaving 99.5% of our emissions intact.
And, according to one recent study, even if Americans eliminated all animal protein from their diets, they would reduce U.S. greenhouse gas emissions by only 2.6 percent (White RR, Hall MB 2017).
Demand for meat is rising in developing and emerging economies, with the Middle East, North Africa and Southeast Asia leading the way. In 2015, average annual per-capita meat consumption in developed countries was 42 pounds (92 kilograms), compared to 11 pounds (24 kilograms) in the Middle East and North Africa and eight pounds (18 kilograms) in Southeast Asia.
Given projected population growth in the developing world and the urgency of the problem, it’s critical for developed countries such as the United States to promote the most sustainable livestock practices at home and abroad.
The ecological and economic benefits of holistic farming that combines crops with livestock are very real. Research confirms that farmers can mimic the self-regenerating nature of natural ecosystems by combining no-till soil cultivation, crop rotation, animal manure, and rotational livestock grazing methods that mimic the behavior of wild herd animals such as bison.
The authors of a recent paper expressed the concept in scientific terms: “Mimicking the nutrient coupling/decoupling processes of natural ecosystems by diversifying plant and animal components of no-till integrated crop-livestock operations is an essential feature of the design of agroecological systems that support self-regulating feedbacks and lend resilience while increasing productivity and ecosystem service provision.” (Carvalho PCF et al. 2018)
[Editor’s note: Rotational grazing of cattle — if carefully and intensively managed — is proven to deliver several benefits. It can help protect and restore grassland (thereby sequestering carbon), disrupt the lifecycles of pests, promote stable production in poor growing conditions (especially drought), yield higher quality forage, decrease weed and erosion problems, and help ensure more uniform soil fertility.
However, some advocates overstate its environmental benefits. For example, in a famous 2013 TED talk, Zimbabwean rancher/ecologist Allan Savory claims that his Holistic Planned Grazing™ method — which requires careful attention to ranch conditions and constant adaption of grazing patterns in response to them — can virtually reverse desertification of grassland and prevent the release of large amounts of carbon.
But it's very difficult to conduct studies of such a highly variable system, and the available independent evidence suggests that rotational grazing can't reverse desertification. Further, it's clear that some advocates of Savory's method greatly exaggerate the amounts of carbon sequestered by grassland.
Those critiques were echoed in a lengthy 2013 article at Slate.com, in a comprehensive 2016 evidence review from the Centre for Organic Food & Farming at Sweden's University of Agricultural Sciences, and in an undated summary from Britain's Food Climate Research Network.]
Cattle, goats, and sheep make marginal land productive
Removing animals from U.S. agriculture would reduce national greenhouse gas emissions slightly — but also make it harder to meet many people’s nutritional needs.
Many critics of animal agriculture are quick to point out that if farmers raised only plants, they could produce more pounds of food and more calories per person.
However, humans also need micro- and macronutrients that are much more highly concentrated in meats — and in eggs and milk.
Importantly, only certain plant parts are edible and desirable. For example, the energy (calories) in plants that livestock consume is most often contained in cellulose, which is indigestible for humans and many other mammals.
But cows, sheep and other ruminant animals can break cellulose down and release the solar energy contained in this vast resource — and the FAO estimates that up to 70% of all agricultural land can only be used to graze ruminant livestock (e.g., beef, goats, and sheep).
And because — compared with most plant foods — meat is far more nutrient-dense and valuable per pound, raising livestock adds nutritional and economic value to agriculture, which is especially valuable in developing countries.
The world population is currently projected to reach 9.8 billion people by 2050. Feeding this many people will raise immense challenges. So is important to remember that, per serving, meat is substantially more nutritious than vegetarian options, while ruminants like cattle, goats, and sheep thrive on land that’s unsuitable for farming and wild feed people can’t eat.
What about the feeding of grain — mostly corn, which people can eat — to livestock?
Only in developed countries, and only during the last quarter or so of their lives, are most beef (and a small percentage of sheep) fed corn as 60-85% of their diet, along with human-inedible distiller’s grain. Interestingly, relative to the proportion used as animal feed, the proportion of corn used in America to make fuel (ethanol) has risen dramatically, while the percentage eaten by people hasn’t changed significantly.
Cattle, land, and water: Misperceptions abound
Raising livestock provides much-needed income for small-scale farmers in developing nations, supporting an estimated 1 billion people worldwide.
On a global scale, the Earth’s 1.5 billion cattle are found in almost all climatic zones. They’ve been bred for adaptations to heat, cold, humidity, extreme diet, water scarcity, mountainous terrain, dry environments, and for general hardiness.
Cattle eat human-inedible plants on marginal lands and produce 66 million tons of beef, 6.5 billion tons of milk, macro- and micronutrients, fibers, hides, skins, fertilizer and fuel.
Even in developed countries, the usable byproducts and ecological benefits (e.g., soil improvement) from well-managed, properly grazed cattle extend well beyond the huge value of their milk and meat. And — especially for small farmers in developing countries — they provide transportation, plowing power, income, and a form of banking.
Grass and rangelands make up 80% of the 2.5 billion hectares (6.2 billion acres) of land used for livestock production, and most of this land is considered too marginal to convert to cropland. (Globally, some 98% of cattle either feed exclusively on grassland, or are raised on small farms that raise crops and livestock.)
Removing ruminants like cattle and sheep from this non-arable land would mean that 57% of the land currently used for livestock would no longer contribute to global food production. Rain — called “green” water, as opposed to “blue” surface and ground water — would still fall on rangelands free of cattle, but it wouldn’t produce any food for people.
Life-cycle assessments of beef production show large amounts of required land and water, but ignore the critical fact that rain falling on non-arable land has no alternative use for food production — except indirectly after a small proportion finds its way into aquifers, rivers, and lakes.
Finally, it’s important to note that livestock — when grazed rotationally to improve rather than degrade grassland — can enhance soil health and grassland ecosystems (Russell JR 2015).
Professor Mitloehner receives research funding from the California Air Resources Board (CARB) and the California Department of Food and Agriculture (CDFA). You can read his original article at The Conversation.
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