Animal Agriculture Responsible For Exceeding 4 Planetary Boundaries, Says Oxford Professor

An Oxford professor, who is an expert in food systems and climate change, has named animal agriculture as the main cause of breaching a range of planetary boundaries.

In a presentation at the Oxford Martin School, Professor Paul Behrens explained how the food system is driving us “far beyond the limit of a sustainable planet” for different boundaries. There are nine boundaries, and as of 2023, we have exceeded six of them: novel entities, climate change, biosphere integrity, land system change, freshwater change, and biogeochemical flows.

Fossil fuels are the main cause for exceeding the climate limit. Substances such as microplastics lead for breaching the safe limit of novel entities in the environment. But the food system, and farming animals in particular, is the main driver for the other four breaches, said Behrens.

“Mostly all of this across this entire board is driven by animal agriculture,” he said.

An inefficient system

Behrens goes on to explain that it’s “in large part” the inefficiency of turning animals into food that makes farming animals so environmentally damaging.

“If you look across different animal products, you’re throwing away between 80 odd percent to 97 percent of the calories that are in those products,” he said.

Farming animals takes up 80 percent of land used for agriculture, both for grazing animals and growing animal feed. To produce a single kilo of beef, the most inefficient food, a cow has to eat 25kg of animal feed. A sheep needs 15kg, and a pig 6.4kg. A chicken will need around 3.3kg of feed, which is more than they weigh at slaughter. Farmed animals consume over a third of the world’s calories from crops, but only provide 18 percent of calories that humans consume.

Plant rich diets ‘the biggest opportunity’

A cow at a farm looking at the camera — Adobe Stock Animal agriculture is a leading cause of the climate crisis

In the presentation, Behrens reiterated findings from studies led by Oxford scientists that show plant-based diets are a highly effective solution to climate and environmental problems.

“Shifting to a plant-rich diet, especially in high income nations, is the biggest opportunity that we have for meeting climate targets,” said Behrens. This shift in high income countries “would save vast amounts of land.” Focusing specifically on the UK, he said that “we would save an area almost the size of Scotland.” Globally, it would save an area “roughly the size of the EU.”

Behrens also explained the “double dividend” of freeing up agricultural land. “If you were able to save that land and return it to natural vegetation, you’d draw down about 14 years of global agricultural emissions,” he said. “It’s as a double dividend. So if you think about moving from meat consumption to say legume consumption you get that reduction, but you get the same reduction again if you’re able to save that land that the animals were on and then draw down onto that land.”