[hombre_fatal]

That paper makes the opposite argument than you thought it made. Even from a freshwater perspective it’s more water-efficient to get calories/protein/fat directly from crops than from animal products.

Since you like their work, the authors of your paper answered that question more generally here https://link.springer.com/article/10.1007/s10021-011-9517-8 where they conclude "The water footprint of any animal product is larger than the water footprint of crop products with equivalent nutritional value".

You make some often debunked claims, like we'd have to plant more crops to feed humans directly if we stopped eating meat.

This shouldn't make intuitive sense to you since animals eat feed grown on good cropland (98% of the water footprint of animal ag) that we could eat directly, and we lose 95% of the calories when we route crops through animals.

[throwup238]

You’re confusing my argument. I’m not arguing that meat is more efficient than plants; that by itself is obviously untrue because of the trophic efficiency loss. I’m arguing that meat uses marginal resources that would otherwise be useless for growing food. If we eliminate meat we’d eliminate a lot of marginally productive farmland that is naturally irrigated and have to replace it with industrialized irrigation farming that will be significantly more expensive and use more water and energy. Maybe if we had a global cultural reset with industrialized farming, but no one is going to be happy replacing their beef and chicken with the corn and barley and hay that those lands normally grow, much of it inedible to humans.

That paper isn’t actually debunking anything that I’m saying. If the water foot print per calorie is 20x for beef but the feed is grown with 90% of its water from rainfall, that’s not a 20x bigger footprint in a way that practically matters because most of that water is unrecoverable anyway. The water that is recoverable just makes it through the watershed.

Meat is a way to convert land that cant grow things people can or want to eat into things that people will eat. That pastureland and marginal cropland growing animal feed can’t just be converted to grow more economically productive crops like fruit and vegetables without Herculean engineering effort and tons of water and fertilizer. Instead the farming would have to stress other fertile ecosystems like the Southwest which would make the water problems worse, even if their total “footprint” is smaller. The headline that beef uses 20x more water per calorie completely ignores where that water comes from and how useful it actually is to us.

I don’t doubt that we can switch to an all plant diet as a species but people vastly underestimate the ecological and societal cost to do so.