Livestock provide just 18 per cent of calories but take up  83 per cent of farmland and are responsible for 60 per  cent of agriculture’s greenhouse emissions.

Massive changes to food production and people’s diets are essential to maintain the planet’s capacity to feed a growing population according to the biggest analysis ever conducted of the food system’s impact on the environment.

The comprehensive study, published in Nature magazine (October 2018), created and used a database of 40,000 farms in 119 countries covering 40 food products that represent 90 per cent of all food that is eaten.

It analysed the full impact of these foods on land use, climate change emissions, freshwater use and water pollution and air pollution.

The lead researcher, Marco Springmann from the University of Oxford, said the current trajectory of food production would smash critical environmental limits, beyond which humanity would struggle to live.

“We are really risking the sustainability of the whole system. There is no magic bullet. But dietary and technological change [on farms] are the two essential things,” he said.

The researchers found a global shift in diet was needed to keep climate change even under 2°C, let alone the 1.5°C recently recommended by a landmark United Nations report.

This diet would require the average world citizen to eat 75 per cent less beef, 90 per cent less pork and half the number of eggs, while tripling consumption of beans and pulses and quadrupling nuts and seeds.