According to Our World in Data, grazing land for livestock and farming land for animal feed production combine to take up an astonishing 40 million square kilometers (15.4 million square miles) of land. That's well over a quarter of the Earth's entire dry land area, and nearly 40% of the land defined as "habitable." This is one of the reasons the meat-heavy Western diet is under fire as environmentally unsustainable; growing plants to feed animals makes wretchedly inefficient use of land, which could otherwise be left as forest or used for other purposes.