See https://news.ycombinator.com/item?id=20552303 (a few comments above) why meat production is orders of magnitude worse than producing food directly from plants.

Here is a land use graphic from Our World In Data that also includes information on what fraction of consumed calories and proteins are provided by the uses.

https://ourworldindata.org/uploads/2013/10/Land-use-graphic-...

This graphic is used in the article https://ourworldindata.org/yields-and-land-use-in-agricultur...

I totally recognise this. In this example, and the comment below, you measure in unit of nutrition (which I agree is the important factor), but no one has disputed that a human diet from plants compared to meat would not require more usage of arable land. Humans require a larger variety of food than livestock does, so you can't just use efficient (efficient as in terms of nutrition per hectare) plants for humans.

My concern is that we don't have enough land for this, and the fear/threat of overpopulation is already upon us. And has been for decades.

Are you really thinking this through?

Consider that all of the land currently used for livestock were converted. You then _also_ have all of the land used for feedstock for the livestock.

And then there's the fact that most diets globally are predominantly vegetable based anyway - meat is a rare addition.

Land used for livestock != Land used for plants.

You can't convert it, or it's already converted. Usually for corn.

"The new research shows that without meat and dairy consumption, global farmland use could be reduced by more than 75% – an area equivalent to the US, China, European Union and Australia combined – and still feed the world." https://www.theguardian.com/environment/2018/may/31/avoiding...

> But doesn't a vegetarian diet require more hectares than a meat based one?

The animals we eat are mostly fed by what is cultivated on the arable land, exactly because of the modern habits of everybody eating meat every day. Most of the animals never see the pastures. The demand is too big and getting much bigger.

So we feed the animals, and most of the energy stored in their food is converted to the maintenance of the life of the animal, not the meat you get when you kill it.

Compare that with feeding the humans directly (with mostly vegetarian diet): most of the animal food you grow, transport and feed to the animals never end up becoming meat.

See for example:

https://iopscience.iop.org/article/10.1088/1748-9326/11/10/1...

Am I missing something or your statement sounds like livestock do not require land to grow their food?

Example from ten percent law [0]:

> Sun releases 1000 J of energy, then plants take only 100 J of energy from sunlight; thereafter, a deer would take 10 J from the plant. A wolf eating the deer would only take 1 J. A human eating the wolf would take 0.1J, etc.

We can go directly from plants to people instead of using land, energy and resources to grow plants to feed animals for human consumption with 10% efficiency.

[0] https://en.wikipedia.org/wiki/Ecological_efficiency#Ten_perc...

Don't the animals themselves need a load of veggies? And only a small proportion of that becomes cow/pig/etc. So if that land were just used directly for human consumption, you'd need less of it.

Total emissions per unit of nutrition is the relevant factor.

The only way that meat could win on either metric is if livestock are able to subsist on a diet far less varied than humans; essentially if they are better able to convert lower quality feedstock into higher quality meat.

Are you saying livestock does not live on a diet less varied than humans? As I understand it, they aren't as picky about food as humans are.

Livestock mostly lives on soy and corn, things that humans can eat too (or, growing on lands that could produce human food). Some meat can be had in a sustainable way, animals are part of a sustainable agriculture as they can eat food waste or graze on low productivity (or recovering) lands, while naturally adding fertilizer to the soil. The current level of industrial meat production is quite far from that.

The idea that animals only eat food that humans can't consume is very strange. The animals get fed whatever is cheapest on the market, even if that involves burning the rainforest and depleting its soil permanently or feeding them skittles.

"Picky" is a strange way to put it.

Our baseline should be what is required for a healthy body and brain. We can go up from there.

Going down from the current level is farcical. We're in a crisis.

I like me an avocado as much as the next person, but if they need a 500% tax (invented, I don't actually know) to incorporate externalities, they need it. End of.

Like, seriously. It doesn't matter what we "want" at this point. Carbon needs pricing or we are totally fucked.

> But doesn't a vegetarian diet require more hectares than a meat based one?

No, because livestock need food too and are horribly inefficient at turning food/water into meat.