> I think these figures are pretty misleading. First of all, they only look at calories, not protein.
See the link - 63% of the global protein supply already comes from crops while crops only make up 23% of agriculture land so meat isn't as efficient a source anyway:
https://ourworldindata.org/agricultural-land-by-global-diets
> If you wanted to replace all the meat and dairy with equivalent protein substitutes you’d be looking at huge amounts of land for growing soybeans, peanuts, tree nuts
Most livestock aren't eating grass though, they're eating crops like soy because soy is full of protein (and that land use is included in the 40 million km^2 figure).
https://en.wikipedia.org/wiki/Soybean
"Around 80% of the global soybean crop is used to feed livestock.[46] Soya imports represent 47% of Europe’s deforestation footprint"
> Replace all the milk with almond milk
Or rice milk, oat milk, or soy milk. When cows are eating soybeans to produce milk right now, soy milk is always going to be more efficient.
Plant based milks are all significantly more efficient than diary milk for emissions, land and water use too: https://www.bbc.co.uk/news/science-environment-46654042
Also, the focus on protein is just a distraction. It's not difficult to get protein from plants alone and most Americans eat too much protein already:
https://www.nytimes.com/2017/07/28/well/eat/how-much-protein...
"Most American adults eat about 100 grams of protein per day, or roughly twice the recommended amount."
> Good luck growing soybeans on a bunch of jagged cliffs.
If we were only farming grass fed cows on jagged cliffs, it would be less of a problem compared to mass deforestation to grow soybeans to feed to cows in intensive farms. The latter is the reality right now for everyone to have access to cheap meat but it's not sustainable.