Does animal farming cause biodiversity loss?

The objection

“Climate I get, but biodiversity? That’s about poaching and palm oil and habitat, not whether I eat a burger.”

The answer

Poaching and palm oil do threaten wildlife, and the objection is right that habitat is the heart of it. Yet most of the forest that people clear becomes farmland [5], and most of the world’s farmland is used for meat and dairy [3].

What is the biggest cause of biodiversity loss?

Changes in how people use land and sea are the biggest cause, according to the 2019 global assessment by IPBES, the intergovernmental science-policy platform on biodiversity [1]. It ranked them first of the five direct drivers of nature’s decline, ahead of the direct exploitation of wild species, which takes in poaching, and then climate change, pollution and invasive species [1]. More than a third of the world’s land surface now goes to crops or livestock, the assessment found, with 25% of ice-free land used for grazing, including about 70% of the world’s drylands, against 12% for crops [1]. Poore and Nemecek’s 2018 analysis of data from 38,700 farms [2] showed how lopsided that use is: in Oxford’s summary, meat and dairy use 83% of the world’s farmland while providing 18% of its calories and 37% of its protein [3].

How much deforestation is caused by livestock?

Pasture for livestock, mostly cattle, accounts for about two-fifths of the world’s deforestation [4][5]. Singh and Persson (2026) traced 121.8 million hectares of forest cleared for farm and forestry products in 179 countries from 2001 to 2022, and found that pasture, mainly for beef, took about 42% of it [4]. The UN Food and Agriculture Organization’s satellite survey, published in 2021 and covering 2000 to 2018, put livestock grazing behind almost 40% of forest loss, farming of every kind behind almost 90% of global deforestation, and grazing behind almost three-quarters of it in South America [5]. Palm oil is a real cause too, but oil palm, soy and every other oil crop together accounted for 16% in the 2026 study, well under half the share of pasture [4]. Forest plantations took 14% and the staple crops maize, rice and cassava about 11% [4]. Singh and Persson add that their pasture figure cannot separate land cleared for grazing from land cleared on speculation [4].

Do farm animals outweigh wild mammals?

Livestock outweigh all the world’s wild mammals by about ten to one, going by the census of mammals that Greenspoon and colleagues published in 2023 [6]. It put livestock at about 630 million tonnes and humans at 390 million, against about 22 million tonnes for every wild mammal on land and 39 million for those at sea [6]. Greenspoon and colleagues call it a provisional census, and the wild figures are uncertain, with 95% intervals of 13 to 38 million tonnes on land and 20 to 80 million at sea, yet even at the top of both ranges livestock would outweigh wild mammals by more than five to one [6]. Domestic pigs alone weigh almost twice as much as all wild land mammals put together [6]. The authors caution that biomass is no direct measure of conservation status, and they read the imbalance as the mark of a growing human population, rising demand for animal products and the spread of factory farms [6].

Would eating less meat help wildlife?

Eating less meat would help mainly by freeing land. Scarborough and colleagues (2023) linked the recorded diets of 55,504 people in the UK to food footprints, and the diets of low meat-eaters, on under 50g of meat a day, used 43.8% as much land as those of high meat-eaters, on 100g or more, with an uncertainty range of 20.7 to 65.4% [7]. On the study’s own measure of harm to wildlife, the estimated extinction toll on land vertebrates, a big gap appeared only for vegans, whose diets carried about a third (34.3%) of high meat-eaters’ toll, and the authors note that this measure is far less certain: the range for vegans ran from 12.0 to 65.3%, and for vegetarians from 24.5 to 102.3%, past parity with high meat-eaters [7].

Leaving out meat and dairy altogether frees more land still: in Oxford’s summary of Poore and Nemecek (2018), the world could cut its farmland by more than 75% and still feed itself, releasing an area the size of the US, China, the European Union and Australia combined [3]. Almost three-quarters of the world’s farmland is pasture, and about two-thirds of that pasture is unsuitable for growing crops, according to Our World in Data (2021), but natural vegetation and ecosystems could return to the land a plant-based diet frees [8]. What would become of that farmland is a question of its own.