Let’s look at why this is not the case. In the chart here we see the amount of agricultural land the world would need to provide food for everyone. This comes from the work of Joseph Poore and Thomas Nemecek, the largest meta-analysis of global food systems to date. The top bar shows the current land use based on the global average diet in 2010.

As we see, almost three-quarters of this land is used as pasture, the remaining quarter is cropland. If we combine pastures and cropland for animal feed, around 80% of all agricultural land is used for meat and dairy production.

This has a large impact on how land requirements change as we shift towards a more plant-based diet. If the world population ate less meat and dairy we would be eating more crops. The consequence – as the following bar chart shows – would be that the ‘human food’ component of cropland would increase while the land area used for animal feed would shrink.

In the hypothetical scenario in which the entire world adopted a vegan diet the researchers estimate that our total agricultural land use would shrink from 4.1 billion hectares to 1 billion hectares. A reduction of 75%. That’s equal to an area the size of North America and Brazil combined.

But importantly large land use reductions would be possible even without a fully vegan diet. Cutting out beef, mutton and dairy makes the biggest difference to agricultural land use as it would free up the land that is used for pastures. But it’s not just pasture; it also reduces the amount of cropland we need.