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University of Cambridge researchers have developed a new way to measure the impact of our food production on other species' survival around the world.

It reveals that between 700 and 1,100 species of vertebrate are likely to go extinct in the next 100 years, if global land-use for agriculture does not change. This figure does not account for future population growth, and is probably a huge underestimate.

By considering the productivity of any piece of land, the team can figure out the "per kilogram impact" of each commodity per year on biodiversity.

Some of our everyday favorite foods—like coffee, cocoa, tea and bananas—are all grown in tropical regions of the world. These have a much greater impact on species extinctions than those from temperate areas, because tropical regions are so rich in biodiversity.

The study found that eating beef and lamb has the biggest impact of all foods on species extinction—although this varies significantly depending on where the meat is produced.

The UK's food "extinction footprint" is almost entirely due to imports. For example, beef produced in Australia and New Zealand, which is now being imported to Britain in much bigger quantities since Brexit, is thirty to forty times more likely to lead to species extinctions than beef produced in the UK and Ireland.

Of the many ways that our appetites harm biodiversity, land-use change and habitat destruction for farming are the most damaging.

The report was in the journal Nature Food on Tuesday 9 September.

"Every time anyone eats anything, it has an impact on the other species we share the planet with," said Dr. Thomas Ball, a postdoctoral researcher in the University of Cambridge's Department of Zoology, first author of the report.

He added, "Rearing the cattle for one kilo of beef needs a huge amount of land, which displaces a lot of natural habitat. On average, that has a much bigger impact on species' survival than growing one kilo of vegetable protein like beans or lentils.

"Our study shows that eating beans and lentils is 150 times better for biodiversity than eating ruminant meat. If everyone in the UK switched to a vegetarian diet overnight, we could halve our biodiversity impact."

The work is based on the 'LIFE' metric ("Land-cover change Impacts on Future Extinctions") developed by the University of Cambridge—which quantifies how changes in land use, such as deforestation or habitat restoration, are likely to affect the extinction risk of 30,875 terrestrial vertebrate species worldwide.

Guiding policy decisions

In the past six decades, almost a third of the global land surface has been altered for agriculture. Halting species extinctions arising from this is a key policy concern.

Ball's work with Dr. Jonathan Green at the Stockholm Environment Institute and the Joint Nature Conservation Committee (JNCC) has resulted in the LIFE metric becoming part of the UK Government's toolkit for measuring the global environmental impacts of the UK's consumption of agricultural commodities.

They've pulled together national data on the consumption and provenance of 140 food types, and integrated this with the LIFE metric to quantify the impact that different trade and agricultural policies might have on global species extinction risk—the first time this has ever been done.

"When it comes to decisions about producing food, it's not enough to focus on one country in isolation. We have a UK agricultural policy that incentivizes farmers to set aside more land for nature, and reduce food production. But if that means we're making up the shortfall by relying on imports from more biodiverse places, it could cause far more damage to the species on our planet in the long run," said Ball.