The guesses differ, but only one person was correct. It turns out to be 98%! See below: 1% of land we use goes to Urban & built-up land, and 48% goes to Agriculture, so 48/49th of human-made land goes to agriculture.
XFEDI
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This would lead us to the second question:
What percentage of that agricultural land could we free up by shifting to plant-based diets? 🌱