But animal ag is far from sustainable, unfortunately.
Climate change, resource depletion, deforestation, loss of biodiversity, pollution, overpopulation, soil erosion, and overfishing are all symptoms of ecological overshoot.
Agriculture is a key culprit in most of those symptoms, and animal ag accounts for 80% of all agriculture.
Animal ag is directly responsible for majority of deforestation, is a major driver of biodiversity loss, has twice the greenhouse gas emissions than plant based foods, uses much more fresh water, pollutes the waters and causes dead zones in oceans, overfishing threatens us with empty oceans in 2040's, destroys our soils, etc. etc.. The reforestation potential of animal ag lands is so huge, that we could store our entire 1.5C carbon budget in those lands.
We can free up the area a size of Africa (cca 9 Indias) by switching to plant based diets, and use it for reforesting/rewilding.
If the world adopted a plant-based diet we would reduce global agricultural land use from 4 to 1 billion hectares - https://ourworldindata.org/land-use-diets
Reforestation potential of pastures (and abolishment of animal ag) would allow us to store the entire 1.5C carbon budget by rewilding/afforesting previously forested pastures. It would also stop biodiversity loss, which is a very serious problem in this day and age. - https://www.nature.com/articles/s41893-020-00603-4
Rapid global phaseout of animal agriculture (and reforesting) has the potential to stabilize greenhouse gas levels for 30 years and offset 68 percent of CO2 emissions this century - https://journals.plos.org/climate/article?id=10.1371/journal...
Beef, soy for animal feed and palm oil are responsible for 60+% of tropical deforestation - https://ourworldindata.org/drivers-of-deforestation
Our global food system is the primary driver of biodiversity loss - https://www.unep.org/news-and-stories/press-release/our-glob...
The way we eat could lead to habitat loss for 17,000 species by 2050 - https://www.vox.com/future-perfect/22287498/meat-wildlife-bi...
Livestock and climate change: what if the key actors in climate change are... cows, pigs, and chickens? - ttps://www.semanticscholar.org/paper/Livestock-and-climate-change%3A-what-if-the-key-in-Goodland-Anhang/6704c7a0777c82357704d82b9ae8007c1197cb07?p2df
The global production of food is responsible for a third of all planet-heating gases emitted by human activity, with the use of animals for meat causing twice the pollution of producing plant-based foods - https://www.theguardian.com/environment/2021/sep/13/meat-gre...
Reducing food’s environmental impacts through producers and consumers - https://www.science.org/doi/10.1126/science.aaq0216
Mass Extinctions and Their Relationship With Atmospheric Carbon Dioxide Concentration: Implications for Earth's Future - https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF00...