Beef and dairy production accounts for 41% of the biodiversity damage caused by the world's farmland, according to an international study involving researchers from the Oxford Martin School at the University of Oxford.
Published in Nature Food, the research also shows that the environmental impacts of farming are concentrated in relatively few places. Two-thirds of the world's carbon loss from agriculture and two-thirds of its biodiversity loss occur on just one-third of global farmland, creating opportunities to tackle both challenges together.
Agriculture has already caused the loss of an estimated 300 billion tonnes of stored carbon and put around 14% of species at risk of extinction through land conversion. The carbon lost from converted ecosystems is equivalent to around 140 years of agricultural emissions at today's rates.
Much of this damage is concentrated across parts of South America, sub-Saharan Africa and South-East Asia. Half of all carbon loss comes from just 12% of farmland, suggesting that focusing restoration efforts on these areas could deliver benefits for both climate and biodiversity.
Animal-sourced foods account for most of agriculture's environmental damage while providing a relatively small share of the world's calories. Beef and dairy have by far the greatest impact, contributing 29% of total carbon loss and 41% of biodiversity loss because producing them requires so much land. On average, animal-sourced foods are associated with eight times more carbon loss and 14 times more biodiversity loss per calorie than plant-sourced foods.
Global map showing where farmland causes the greatest damage both to carbon storage and biodiversity.
International trade also shifts these impacts around the world. Around 18% of farmland's carbon and biodiversity losses are linked to food traded across borders. Brazil is the largest net exporter of both carbon and biodiversity loss, while China is the largest net importer, with trade in animal products accounting for many of the largest flows.
The researchers also examined the potential benefits of restoring the most heavily affected land. Returning the 30% of farmland with the highest combined carbon and biodiversity losses to natural habitat could sequester around 170 billion tonnes of carbon, equivalent to roughly 15 years of global fossil fuel emissions, while preventing around 60% of the extinction risk currently associated with agricultural land.
"Climate and nature have been treated as separate problems for too long, with separate targets and separate negotiations."
Professor Paul Behrens
Professor Paul Behrens, Oxford Martin School, University of Oxford, said: ‘Climate and nature have been treated as separate problems for too long, with separate targets and separate negotiations. Our findings show they're often the same problem on the same piece of land, with two-thirds of the carbon damage and two-thirds of the biodiversity damage from farming happening on just a third of agricultural land. There is a huge opportunity to target the specific places and foods. The same actions can deliver for the climate and for nature at once.’
Researcher Baoxiao Liu, Institute of Environmental Sciences (CML), Leiden University, said; ‘Food production on farmland has ongoing environmental costs that are often overlooked. We link long-term damage to both climate (carbon loss) and nature (biodiversity loss) to foods we currently consume. If farmland were no longer used for food, it could potentially be used for nature, helping to restore carbon stocks and provide habitat for more species. Our daily eating choices therefore have a real impact.’
The research was led by Leiden University in collaboration with the University of Oxford and China Agricultural University.
The paper, High-resolution carbon and biodiversity mapping shows correlated losses across space and agricultural products, is published in Nature Food.