There are inefficient ways to produce food, and then there is animal agriculture. A new study published in Nature Food has put numbers on just how grotesquely lopsided the equation has become.
Foods from animals provide less than 15% of humanity’s calories, yet they are responsible for 71% of biodiversity loss and 59% of carbon loss caused by food production on agricultural land.
Per calorie, the average carbon loss associated with foods from animals is 8 times higher than for plant foods. Their biodiversity impact is 14 times higher.
Fourteen times.
This is not a marginal difference that can be fixed by tinkering around the edges. It is a fundamentally inefficient way of feeding humans.
We are using the planet to feed animals
The reason is hardly mysterious.
According to the study, animal agriculture uses around 79% of agricultural land associated with food production, while providing less than 15% of calories and just 37% of protein.
Animals need somewhere to live. Grazing animals require enormous areas of pasture. Pigs and chickens require crops grown elsewhere and transported to them. We grow food, feed that food to another animal, keep that animal alive, and then consume a fraction of the energy and protein that went into the system. Or we could eat plants.
The land bill for that inefficiency is staggering. FAO figures show that agricultural land covered around 4.8 billion hectares in 2023, more than one-third of the entire land surface of Earth. Around 1.6 billion hectares were cropland and another 3.2 billion hectares were permanent meadows and pastures. And land is not empty space.
It was habitat.
Cows are especially destructive
The new research found that meat and milk from cattle alone account for 29% of carbon loss and 41% of biodiversity loss associated with agricultural land.
Again, the problem is largely land.
Cows require enormous areas, whether they are grazing directly or being confined while crops are grown elsewhere to feed them. Calling one system “extensive” and another “intensive” does not magically make the land appear.
Previous research from Chatham House made the same underlying problem painfully clear. Animal farming occupied around 78% of agricultural land, despite meat and dairy supplying only 18% of calories and 37% of protein in the dataset used for its global land analysis.
We surrender most of the land for a minority of the food. Then we act surprised when wildlife disappears.
Agriculture is eating the living world
This is not merely a carbon problem.
The global food system has already been identified as the primary driver of biodiversity loss. Chatham House reported that agriculture was a recognised threat to 24,000 of the 28,000 species at risk of extinction assessed in the data it reviewed.
Over the previous 50 years, conversion of natural ecosystems into cropland and pasture had been the principal cause of habitat loss. Forests become fields. Grasslands become pasture. Habitats become feed crops. Wild animals lose the places where they eat, breed, shelter and live because we have decided that vast areas of the planet should instead be devoted to producing cows, pigs, chickens and the crops used to feed them.
Even supposedly wildlife-friendly farming does not escape this basic reality. Chatham House noted that even the most wildlife-friendly agricultural systems support less biodiversity than pristine or unmanaged ecosystems.
The comparison is not merely factory farming versus nicer farming.
It is farming versus nature.
Look at what we have replaced
Perhaps the most disturbing statistics are not about hectares at all.
By the Chatham House analysis, farmed cows and pigs represented around 60% of mammalian biomass, while wild mammals represented just 4%. Farmed chickens accounted for 57% of bird biomass. Wild birds accounted for 29%.
We have not merely expanded agriculture into nature. We have replaced enormous numbers of wild animals with animals deliberately bred into existence because humans want something from their bodies. And the ecological consequences continue long after the individual animal reaches the slaughterhouse.
The obvious solution
Researchers identified areas where carbon and biodiversity losses overlap particularly strongly. Restoring half of those hotspots could, according to their modelling, store carbon equivalent to around 24 years of global fossil-fuel emissions and potentially spare approximately 11% of species from extinction. But restoration requires land.
And freeing land requires confronting what currently occupies most of it.
This is why endlessly debating whether cows should graze differently or chickens should eat a slightly different feed misses the scale of the problem.
Animal agriculture demands huge amounts of land because converting plants into animals and then animals into food is inherently wasteful.
None of this is why animals deserve freedom from exploitation. Their rights do not depend on whether exploiting them happens to be environmentally efficient. But ecological destruction is another consequence of the same assumption.
We took animals who did not belong to us, turned them into commodities, devoted most agricultural land to breeding and feeding them, displaced wild animals in the process, and received less than 15% of our calories in return. That is not feeding the world efficiently. It is consuming the world to feed ourselves animals.