Climate change is scientifically observable.
Changes in global climate patterns have become apparent in the mid-to-late twentieth century. (Climate Reality Project)
It's caused by human activities.
97% or more of actively publishing climate scientists agree that climate-warming trends over the past century are extremely likely due to human activities. (NASA)
The impacts are becoming increasingly severe.
Scientists say the effects of climate change are making extreme weather events far more destructive than they would have been in previous decades. (CNN)
What are the measured climate impacts of farming animals?
Multiple studies show differing specific amounts, but the clear pattern is that animal agriculture is a significant (and widely downplayed) source of the greenhouse gas (GHG) emissions – and loss of carbon sinks – that are contributing to climate breakdown.
Changes to our energy system are essential too, but they will take many years and require billions of dollars along with political will. Sadly, at this time, US leaders are moving in the wrong direction.
Shifting to a plant-based diet is something individuals with access and autonomy have the power to do immediately, without waiting for political will.
Various studies on the percentage of total GHG emissions produced by animal agriculture
The question of which percentage is most accurate is complex and hotly debated.
- The studies with lower GHG estimates face criticism for:
- Leaving out significant impacts of livestock farming (like lost sequestration due to deforestation and soil degradation)
- Allocating certain GHGs sources (such as feed production) to other sectors
- Using a longer, arbitrary, misleading, and unrealistic 100-year time frame to determine global warming potential (it is believed a more appropriate 10-year window would increase this component by a factor of 3 or more)
- Having conflicts of interest/affiliations with the "livestock" industry
- Others criticize the much higher estimate for:
- Using livestock respiration as a proxy for the carbon sequestration foregone when trees are cut down to grow livestock feed
- Lack of peer review
It should be noted that the UN FAO is the self-described partner of the livestock industry, and their prescription is actually more livestock and further intensification. Of their 2006 study, Rajendra Pachauri, who was head of the UN IPCC at the time, said in a public speech:
"I've received a number of emails from people that I respect saying that the 18 percent figure is an underestimate; it's a low estimate and in actual fact it's much higher."
Yet the UN actually lowered their next estimate in 2013. A lengthy back-and-forth went on between the UN FAO and WorldWatch Institute, which ultimately ended with a lack of response from UN FAO.
Additionally, per Dr. Sailesh Rao of Climate Healers, the FAO estimate has vastly under-counted the land use change component of the greenhouse gas emissions contribution of animal agriculture. It only takes into account the above ground and soil carbon contained in the land deforested each year, while omitting their loss in the land being degraded each year. While 20 million acres are deforested each year, the UNCCD has reported that a whopping 7.2 billion acres are being degraded each year.
It is our understanding that animal agriculture logically contributes far more to climate change than just a relatively small fraction of the problem when:
- GHG impacts are measured on a 10-year timeframe (rather than an arbitrary 100-year timeframe);
- directly-related GHG sources are not allocated to other sectors; and
- resulting foregone carbon sequestration (due to high land use/deforestation and soil degradation caused by animal ag) is included in calculations.
Again, regardless of a specific figure, animal agriculture is clearly a significant driver of climate change – and remember, climate change is just one of the many negative impacts of animal agriculture.
How does animal agriculture exacerbate climate change?
1 - It burns up far more fossil fuels than plant-based agriculture.
The production of one calorie of animal protein requires more than ten times the fossil fuel input as a calorie of plant protein.
(American Journal of Clinical Nutrition)
2 - The following GHG emissions are generated as a result of rearing the animals themselves (in order of potency of global warming potential):
- Carbon Dioxide (CO2) - Results from fertilizer production for growing feed, animal production, processing and transport of refrigerated animal products.
- Methane (CH4) - Results from the digestion process of ruminants. Per the UN FAO, the "livestock" sector accounts for 80% of these agricultural emissions.
- Nitrous Oxide (N2O) - Results from the fertilizer used to grow feed and the animals' subsequent bodily waste. Per UN FAO, the "livestock" sector contributes about 75% of these agricultural emissions.
3 - Carbon sinks are lost due to soil degradation, deforestation, and other land use changes that occur to graze animals and grow their feed.
It is estimated that land holds three times as much carbon as the entire atmosphere. Plants and trees are needed to draw down the carbon already in the atmosphere. Per WWF and Union of Concerned Scientists, animal agriculture is the number one cause of deforestation.
- Researchers have found that 42% of the total emissions reductions that could be achieved from reforestation depend on reducing pasture land.
- Other researchers found that if the land currently used for grazing farmed animals were returned to the native forests that existed on that land in 1800, those forests could sequester more carbon on just 41% of that land than all the carbon added to the atmosphere since 1750.
- Another recent study names "large-scale grazing and other uses of grasslands, as well as forest 'management'" as being "just as substantial as deforestation" on land use changes contributing greatly to climate change.
Large amounts of reforestation and re-wilding simply cannot happen without masses of people – especially in developed and developing nations – switching to a plant-based diet simply because of the excessive land requirements to rear and feed farmed animals.
What measured impacts can a vegan shift make?
Again, various studies show different results, but the pattern is that a shift to vegan diets would make a major dent in fighting our climate crises.
Some of the most convincing support for this idea is as follows:
Project Drawdown – a coalition of scientists, entrepreneurs, and advocates – ranked a plant-rich diet as the number four solution (out of one hundred) to reduce greenhouse gas emissions. Additionally, 3 other solutions among their top 10 (silvopasture, tropical forests, and reduced food waste) also tie in to a plant-based shift.
World Scientists' Warning to Humanity: A Second Notice – a BioScience journal article signed by an unprecedented 15,372 scientists from 184 countries – named meat consumption as a cause of rising GHGs and included “promoting dietary shifts towards mostly plant-based foods" among their "examples of diverse and effective steps humanity can take to transition to sustainability."
The FAIRR initiative – consisting of 40 investors managing $1.25 trillion in assets – are encouraging global food companies to diversify to plant-based proteins to help to reduce environmental and health risks and limit climate change.
Below are the results of three scientific studies that measure the climate impacts a vegan diet can make.
Note: The diet comparisons below are based on local sensitivities, i.e., what happens if one person goes vegan while the rest of the world continues as is. The Independent Climate Research Initiative (ICRI) is aiming to analyze global sensitivities, i.e., what happens with a global vegan shift (estimated to actually result in negative emissions).
Dietary Greenhouse Gas Emissions
How food-related emissions can be slashed
Comparing potential for reducing emissions
Animal agriculture is a significant cause of climate change due to high fossil fuel usage, emissions from the animals' digestive processes and fertilizer for their feed, and lost carbon sinks resulting from land use changes for grazing and growing feed. Shifting to a plant-based diet may be the most effective way to stop climate change on an individual level. If you have access and autonomy, please go vegan today for the animals as well as our planet's future inhabitability.