Eating a plant-based diet, or living a vegan lifestyle, is the single best change an individual can make to their personal habits to be eco-friendly. Whether you purchase grain-fed or grass-fed, distantly or locally sourced, generic or organic, factory farmed or free-range animal products, animal agriculture is the most unsustainable diet for the planet. Transitioning to a plant-based vegan diet helps switch the demand and helps transition industries into more earth-friendly practices.
A recent study by Chai et al. (2019) compared the environmental impact of an omnivorous diet (a diet inclusive of animal products), a vegetarian diet (no meat, but inclusive of eggs and dairy), and a vegan diet (a diet with absolutely no animal products). What the research found was that a vegan diet is the most environmentally sustainable diet, due to requiring less water in food production, occupying less space in farming, and producing less emissions per 2000 calories. If you wish to read this study for yourself, access the link in footnote 1.
In 2018, Oxford University researchers, Poore and Nemecek, followed 38,700 farms across 119 countries in the world’s most comprehensive study to investigate the relationship between agriculture and the environment. The study investigated the agriculture industry’s impact on the environment, focusing on land use; freshwater withdrawals weighted by local water scarcity; and greenhouse gas induced acidification (air pollution) and eutrophication (water pollution). What their research found was that animal agriculture is the most environmentally damaging agricultural practice and stated that “impacts of the lowest-impact animal products typically exceed those of vegetable substitutes, providing new evidence for the importance of dietary change” . If you are interested in a more detailed analysis of the study, you can find it at the link in footnote 2.
To put it most simply, animal agriculture has devastating effects on the environment, globally, nationally, and locally. It is the leading cause of deforestation and land-clearing; the industry drives loss of biodiversity; erosion occurs as a consequence of land clearing, increasing waste and sediment run-off into the waterways, therefore depleting water quality; soil is compacted due to the animals’ heavy footprints, degrading soil quality; it exploits a disproportionately large amount of water resources; and most notably, it produces the most substantial amount of anthropogenic (human-caused) greenhouse gas emissions.
Globally, 50% of Earth’s habitable land is used for agriculture. Of that, animal agriculture, including meat, eggs, and dairy, accounts for 77% of land use. However, animal agriculture only produces 18% of global calorie supply, and 37% of global protein supply. What this means is, despite occupying an overwhelming majority of land, animal agriculture produces disproportionately less food compared to the resources it exploits. In comparison, crops for plant-based foods only occupy 23% of land used for agriculture, while producing 82% of global calorie supply, and 63% of global protein supply. This tells us that it is much more efficient and sustainable to produce and consume plant-based foods as they require significantly less land, while still producing a large supply.
In his article for National Geographic, Foley (n.d.) explained “only 55% of the world’s crop calories feed people directly; the rest are fed to livestock (about 36 percent) or are turned into biofuels and industrial products (roughly 9 percent)”. Foley further argues that this is an inefficient way of attaining food. He says, “for every 100 calories of grain we feed animals, we only get about 40 new calories of milk, 22 calories of egg, 12 of chicken, 10 of pork, or 3 of beef”.
To demonstrate the extent of this disproportionate use of land and resources, at a social level, the animal agriculture industry plays a huge role in the global famine and switching to a plant-based diet would definitely address world hunger significantly. Based off 2019 United Nations data, over 820 million people experience famine every year. A study by Cassidy, West, Gerber and Foley (2013) found that by replacing animal agriculture with “growing food exclusively for direct human consumption [we] could, in principle, increase available food calories by as much as 70%, which could feed an additional 4 billion people (more than the projected 2-3 billion people arriving through population growth)”. This means that we could feed the whole world without excessively exploiting the land.
Why Does Land Use Matter?
If the entire world was to eat the average Australian diet, we would require 158% of habitable land to be used for animal agriculture. However, there is obviously not enough land for that; therefore, it is unsustainable. When countries, such as Australia and the United States, consume unsustainable diets, it puts immense pressure on the environment. This pressure escalates with increased demand as the population continues to grow exponentially.
Why does animal agriculture occupy significantly more land than plant-based crops?
Animal agriculture requires land for producing livestock feed (such as soy and grains), as well as land for grazing the livestock. Land use for livestock feed is problematic because it means that lots of resources, such as land, water, and the livestock feed, are used for meat and dairy production, as opposed to being used for humans.
Many critics of the vegan diet argue that soy plays a huge role in deforestation. While this is true, it has absolutely nothing to do with demands from veganism. Only 6% of global soybean supply is consumed by humans, while 70-75% is fed to chickens, pigs, cows, and farmed fish. The remaining amount is used in vegetable oil, or other non-food products like biodiesel .
As seen in Figure 1, 50% of Earth’s habitable land is used for agriculture, and of that, 77% is occupied by animal farming. This makes the animal industry the greatest human-use of land in the world. But at a more local scale, animal agriculture is the greatest use of land in Queensland too, with 86% of land being used for grazing.
The fact that the majority of Queensland – and Australia, and the world – is used for animal agriculture means there are major implications for the environment. Particularly in Queensland, the animal product industry has devastating consequences for the Great Barrier Reef. Extensive land use for animal products impacts trees, wildlife, waterways, oceans, soil, air quality, and more. The greater the land used for animal agriculture, the more far-reaching the environmental impacts are.
Animal agriculture, particularly beef, is the leading cause of global deforestation and land clearing. Research by Yale University’s School of Forestry and Environmental Studies has found that cattle ranching (farmland used for a large number of cattle) accounts for 80% of current deforestation rates in the Amazon region. The Amazon is the largest exporter of beef in the world, providing a quarter of the global market. Most people assume the issue of land clearing for meat products only exists in the Amazon, because that is all we hear about in the media. However, the reality is that the same trend can be seen in Australia, with beef accounting for 73% of all deforestation in Queensland.
Australia is the second largest exporter of beef in the world. The industry occupies 43% of Australia’s total land mass, making the industry the dominant use of land, and is responsible for 73% of all land clearing in Queensland. According to a joint report by WWF and RSPCA (2017), tree-clearing rates in Queensland have tripled, with an estimated 300,000ha of forest and woodlands being cleared from 2014-2015 alone. In the Great Barrier Reef region specifically, Australia’s top beef production region, cattle accounted for over 93% of all deforestation and land clearing in the region.
Land clearing has detrimental effects on the environment. Most obviously, land clearing results in loss of trees, which are essential in absorbing carbon dioxide from the atmosphere. But in addition, land clearing also leads to loss of biodiversity, as well as erosion and sedimentation (sedimentary and waste run off from farmland into waterways), which has further implications for water quality.
Sedimentation occurs when sediment from land is carried through waterways and settles on the sea bottom. As a result of sediment build up, water turbidity increases, smothering coral and other organisms, reducing their access to light, therefore hindering growth. Activities such as land clearing exacerbate erosion as vegetation provides the ground with protection from wind erosion. When tree cover is removed, soil and other sediments present on the land become exposed to the wind.High levels of sediment are often present in areas with a large amount of livestock grazing activity, showing a direct link between livestock and this environmental issue. It is particularly concerning that the Great Barrier Reef catchments account for half of Queensland’s cattle industry, with thirty-five major river systems draining 424,000km² of land into the Great Barrier Reef. With such a high level of livestock activity occurring along waterways that drain into the vulnerable Great Barrier Reef, it poses significant issues for the health of the Reef.
In addition, in their joint report, WWF and RSPCA (2017) estimated that land clearing in Queensland kills 34 million native wildlife per year. This obviously has devastating impacts on our native wildlife, particularly our koala population.
Unfortunately, not much is being done to stop the effects of land clearing. Land clearing laws (the Vegetation Management and Other Legislation Amendment Bill 2004 (Qld)) that were enacted in order to protect Queensland forests were repealed by the Newman Government in 2012. Since the Newman Government’s intervention, land clearing rates in Queensland, especially in the vulnerable Great Barrier Reef region, increased significantly from prior years when the 2004 Bill was in place.
Animal products require substantially more water resources than plant-based crops and products. This is particularly unsustainable for environments susceptible to drought, such as Australia.
It is unsustainable to prioritise sending resources to industries that do not provide proportionate product to the resources being used. According to Australia’s own meat and livestock industry, Meat and Livestock Australia (2018), a study on Australian cattle farms found that cattle drank 40 litres of water per head per day, while those in subtropical conditions drank an average of 44L/head/day, and those that experienced mild summers and cold winters drank 30L/head/day. It has also been noted that consumption of water increases as heat increases – this is something to consider as Australia continues to break records for hottest days, and as our winters become warmer.
These numbers are significant as, at any given point, there are approximately 26 million heads of cattle in Australia that require 30-44L, or more as heat increases, each per day. Even more concerningly, the majority of these cattle exist in hotter regions,such as the Great Barrier Reef catchment, where the cattle require a more substantial amount of water (for reference of location of cattle, see MLA’s Cattle Distribution Map 2018). As a very rough estimate, this equates to cattle consuming up to 1.40 billion litres of water per day for drinking needs alone.
Additionally, according to Dairy Australia, dairy cows have even higher water needs than beef, with dairy cows requiring between 70 litres (for non-pregnant cows in a cool environment ( <15C)), to 142 litres (for pregnant cows in a warm environment (21-25C)), to over 150 litres (lactating cows, 150 litres minimum, plus morefor weather allowance) of water per HOUR, per cow. Considering Dairy Australia reported that there are approximately 1.65 million dairy cows in Australia, this equates to an absolute bare minimum of 3 billion litres (3049ML) per day, to more than 5.9 billion litres (5940ML) of water used per day for dairy cows’ drinking needs alone.
These numbers do not even factor in the water usage required for feed, nor does it consider the water needs for poultry, lamb, goat, and other animal products.
The animal agriculture industry consumes even more water again through the production of feed, such as grains for cattle. According to 2018-19 data from ABS, 2.2 million megalitres of water were applied to pastures for cereals for feed off, hay, and silage. Including the water used for drinking, this means around 5 million megalitres (5 trillion litres) of water are consumed per year for the cattle and dairy industries alone in Australia – again, even more if we included the needs for lamb, pigs, poultry etc. Keep in mind that animal products only provide 18% of global calories. This is therefore a hugely disproportionate use of water.
Not only is meat an inefficient use of water, but it is not an industry that will ever thrive in Australia due to the nature of Australia’s environment. Australia is consistently in drought. Farmers are always struggling to provide water and feed for their cattle, and as a result, many cattle die in the paddocks. Unless Australia is suddenly granted trillions more litres of water, there is no way conditions will improve in the future, so how can the industry thrive? It can’t. It is imperative that Australia’s agriculture compliments the environment, otherwise farmers will only continue to struggle.
Greenhouse Gas Emissions
Animal agriculture produces a substantial amount of greenhouse gas emissions. According to research by Chai et al. (2019), animal agriculture, especially cattle, accounts for 44% of global methane emissions] . Looking more specifically into the agriculture industry’s greenhouse gas production, animal agriculture contributes 80% of the entire agriculture sector’s nitrous oxide and methane output. Chai et al.’s study (2019) found that ruminant animals, such as cattle, sheep, and dairy, produce the most significant amount of greenhouse gases out of all livestock.
Livestock is Australia’s third largest contributor of greenhouse gas emissions, after energy and transport. However, this statement is deceiving in itself because greenhouse gases are not equal. Western Australia’s Department of Primary Industries and Regional Development explains that due to different levels of potency, some greenhouse gases are worse than others. In particular, methane is 25 times more potent than carbon dioxide, while nitrous oxide is 298 times more potent than carbon dioxide. Therefore, while livestock is the third largest contributor of greenhouse gas emissions, it is very concerning that livestock is the number one source of methane and nitrous oxide in Australia, accounting for 56% and 73% of the country’s emissions, respectively . This is why changing eating habits is arguably more important than ditching the car.
A Queensland Government report published in 2020 has highlighted that Australia’s greenhouse gas emissions from livestock have increased over recent decades. It was reported that “in 2016, Queensland was the largest source of agricultural greenhouse gas emissions in Australia. … animals such as cattle, sheep, horses, goats, and pigs account for 80% of Queensland’s total agricultural emissions”. This is no surprise given that Queensland is Australia’s most productive beef state.
It is important to note that while some data shows a decrease in greenhouse gas emissions from agriculture, this is not due to progression with sustainability, but rather it is due to the occurrence of drought and floods which impact the industry’s activity and productivity .
Organic, Grass-fed, Local Meat – is it sustainable?
When someone announces they are vegan, suddenly every meat eater in the room only eats free-range, organic, grass-fed meat from local farms, “so I don’t cause the same issues as the McDonalds meat anyway”. But how sustainable is free-range, organic, and grass-fed meat? Does local make an environmental difference? Is there any way to eat animal products?
Grass-fed & Organic:
Grass-fed and organic products are no better for the environment than grain-fed, conventional animal products. In fact, these methods of raising livestock puts even more pressure on the environment’s resources, making it even less sustainable.
A study by Avery & Avery (2008) revealed that not only does grain-fed, organic beef take two times longer to produce than conventional beef (meaning the likelihood of this method existing is essentially impossible), but transitioning to an entirely organic and grass-fed system would produce 60% more greenhouse gas emissions per pound of beef. This is due to the increased use of land. In their analysis on beef production from Iowa State University’s Leopold Center for Sustainable Agriculture, Avery and Avery (2007) found that it required 13.3 million acres to produce feed for livestock in the United States in 2007, and a conversion to entirely grass-based produce would require an additional 26.6 million acres to produce the same amount of beef produced that year. Conventional meat, which is already detrimental to the environment, is therefore three times more efficient than grass-fed, organic meat, based on this data. The additional land use would further require more deforestation and water resources, and the impacts of soil compaction would affect this land too, making the problems more far-reaching than they currently are.
Locally sourced animal products still require the same resources as animal products made “further away”. While people are often told, even by the United Nations, that locally-sourced products are better for the environment, Ritchie (2020) explains that there it makes no difference when it comes to animal products. She says,
“GHG emissions from transportation make up a very small amount of the emissions from food and what you eat is far more important than where your food travelled from”.
Below is a graph representing data from Poore and Nemecek’sresearch (2018). It looks at where greenhouse emissions come from in the food supply process, looking at land use, farming, feed, processing, transport, retail, and packaging. It is the largest meta-analysis of global food systems to date. The study includes data from more than 38,000 farms in 119 countries, making it the most comprehensive study on this topic.
The data clearly shows that animal based products, particularly beef, lamb and mutton, dairy, prawns, pig meat, poultry, as well as farmed fish and eggs, produce substantially more greenhouse gas emissions than fruit, vegetable, and grain crops, per kg. As can be seen, transport (shown in red) does not contribute a substantial amount of greenhouse gas emissions at all. Thus, buying locally-sourced animal products will not make your purchase much more eco-friendly at all.
For more information on organic, grass-fed, local meat, an excellent podcast you can listen to is “Plant Proof”. Find episode #104 and they touch on this, plus more. The episode’s archive also has a list of great resources you can read through: https://plantproof.com/our-diet-is-destroying-the-planet-with-environmental-researcher-nicholas-carter/
Any fish you purchase from supermarkets, takeaway shops, and seafood shops are retrieved through commercial fishing. Commercial fishing involves using large trawlers and nets to indiscriminately catch fish. There are a huge number of environmental harms associated with commercial fishing practices. These include overfishing, habitat destruction, bycatch, and derelict fishing gear.
Overfishing refers to when fish are caught at a rate too high for fish numbers to replenish. Overfishing is inevitable as global consumption of fish per capita has doubled from what it was fifty years ago. From 1961-2017, the consumption rate of fish was greater than the rate of population growth, indicating an exponentially increasing pressure on the ocean.
One obvious environmental impact of overfishing is the impact on species. A report by Davies et al. (2009) found that of the 95.2 million tonnes of fish caught in a single year, 38.5 million tonnes – or 40.4% – was bycatch . In 2018, the quantity of fish caught rose to the highest level ever at “96.4 million tonnes – an increase of 5.4% from the average of the previous three years”. According to figures from a United Nations conference on Trade and Development (2018), approximately 90% of global fish stocks are now “fully exploited, overexploited, or depleted”. In reality, these numbers are higher due to illegal and unregulated pirate fishing, where catch numbers are not reported.
From an Australian perspective, a 10-year study of Australia’s declining fish stocks by Edgar et al. (2018) identified overfishing as the leading cause of fish decline. In reefs where fishing was permitted, large fish numbers diminished by 36% . Researchers from James Cook University, Boaden et al., (2015) explained that the removal of large fish from the ecosystems, particularly in the Great Barrier Reef, was changing the biodiversity of the marine environment. Lead researcher of the study, and PhD student, April Boaden, explained,
“A stable and healthy reef includes a high abundance and diversity of predatory fish and a relatively low number of herbivorous and small prey fish. … Predatory fish are extremely important for maintaining a balanced ecosystem on the reef, yet predators such as coral trout, snapper and emperor fish remain the main target for both recreational and commercial fishers. … Predator numbers were severely depleted in heavily fished areas, while smaller prey fish such as damselfish, and herbivores such as parrotfish, had increased greatly in number having been released from predation”. 
There are a number of flow-on effects from overfishing. These include loss of species, resulting in endangered species and disrupting the food chain and local ecosystem; catching threatened species through bycatch; and bottom trawling can damage sensitive habitat areas, like corals, sponges and seagrass beds, disrupting those fragile ecosystems .
Is Sustainable Meat Possible?
It is important to note that this entire article relates to the environmental concerns of mainstream meat – i.e. beef, dairy, poultry, etc. I would like to point out that, from the perspective of the environment, First Nations methods of agriculture is sustainable and has worked for 80,000+ years.
The difference between this agriculture and First Nations’ agricultural practices is that conventional agriculture is mass produced and it does not compliment the Australian environment (exploitative of the resources, cannot thrive as an industry, thus damaging the environment). On the other hand, First Nations peoples have lived on this land for over 80,000 years, and in this time, their agricultural systems did not have detrimental effects on the environment. Knowledge of the land and sustainable practices underpin First Nations agricultural practices.
Some examples of First Nations peoples’ agricultural methods are highlighted in Bruce Pascoe’s book, Dark Emu. One example that Pascoe discusses that I would like to draw attention to is the idea that kangaroo and emu meat, for example, are eco-friendly alternatives to our typical meat sources. An excerpt from Dark Emu explains:
Kangaroo flesh has a low fat content, and is free from impurities, as the animals do not require chemical drenching. They can tolerate a harsh environment and, moreover, their feet do not break up the surface of the soil, or compact it – both of which lead to erosion. (p. 53) 
In this way, it is more environmentally sustainable to consume kangaroo or emu meat, instead of conventional sources of meat. However, it is important to note that First Nations’ traditional agricultural practices did not mass produce meat products in the way Western agriculture does. So if we, as a nation, were to transition to consuming kangaroo meat etc., it would be imperative for First Nations peoples to be in charge of the “farming” or harvesting due to their knowledge of such agricultural practice and conservation. It would also still mean a shift in diets, where animal products do not make up the majority of each meal.
For more information on First Nations peoples’ agricultural practices, check out Dark Emu and Treading Lightly.
Q: Would a transition to plant based farming kill more animals than animal agriculture (e.g. due to pesticides, tractors running over animals in the fields, etc.)?
A: No. First of all, there is a huge difference between intentionally, systematically farming and killing sentient beings (animals that have an awareness), and unintentionally killing a few bugs, mice, etc. in the process of fruit, nut, vegetable, grain agriculture. Another example of animal death that people refer to is shooting pest animals to protect crops. However, even then, the number of animals, whether it is bugs or pests, killed in the process reduces when we eliminate animal agriculture. This is because, as explained under the “land use” section of this chapter, many crops (e.g. up to 75% of soy) are fed to livestock. By eliminating livestock farming, not only do we use less resources and farm less, but it means that there are lessaccidental killings of bugs etc. that will occur as a result. If you choose to eat animal products, even more animals are killed to feed you. 3 billion animals are killed per day for food . Simon Hill has a podcast called “Plant Proof” which touches on this subject. Search for episode #104.
Q: Would there still be sustainability issues if the whole world went vegan? Wouldn’t we require more land to meet the demands so we can feed everyone with plant-based food, now that meat would be gone?
If the whole world ate vegan, it would be more sustainable (by far) than currently with animal products. This is due to the fact that animal products require disproportionately more land, water, food sources than plant-based products.
When we produce animal products, we need to give the livestock lots of food – especially in this case of beef, more food than humans even require themselves – in order to grow them. This adds up so that the animal agriculture industry uses more resources than plant-based crops ever would require.
This has already been explained in above sections, but I will drop a few points from this article below as a reminder:
Therefore, by transitioning the world to a vegan diet, it would significantly reduce the exploitation of resources while being able to provide plenty of food.
 https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjQrvXh1aPqAhXzzDgGHVMXBwQQFjABegQIChAD&url=https%3A%2F%2Ffeed.dairyaustralia.com.au%2F-%2Fmedia%2Flandingpagebuilder%2Ffeed-planning%2Fpdfs%2Fdrinking-water-access-and-quality.pdf%3Fla%3Den%26hash%3D42851563CBA011797A56692D5EDC9CDE2B4E8028&usg=AOvVaw2yDW9h21lJN-RtRydxPnOa p. 2
 https://www.mdpi.com/2071-1050/11/15/4110 p. 11
 https://www.mdpi.com/2071-1050/11/15/4110 p. 11
 http://www.fao.org/3/i3720e/i3720e.pdf p. 62
 http://www.fao.org/3/ca9229en/CA9229EN.pdf p. 65
 Pascoe, B. (2014). Dark Emu. Magabala Books.