Ask Lemmy

Yes and yes.

I remember watching something in the 1990's about this question. The video said that you'd need 6 earths for each human to live at an average American's level of wealth.

I imagine it is worse now.

It won't allow everyone to live comfortably and happily. The resources need to be distributed and there are many, many decisions necessary to define how the resources get distributed. If we lived in an ideal world, where everyone shared the same opinion on these decisions, then we'd all already live comfortably and happily now. But we don't and as much as it sucks, we can't fix being ourselves.

Depends, there are extremely happy people with nothing, and depressed billionaires wanting more than exists.

They key to your question is "sustainably". We can support 8 billion humans without poverty for a time. We can support 10 billion for a shorter time. There is no way to support 8 billion sustainably.

A sustainable civilization uses zero fossil fuels, and recycles 100% of metals and engages in virtually no mining. Our civilization enjoyed a energy metabolism based on fossil fuels with an energy return of 100-1 in early 1900's. That spawns phenominal growth and automation. The easy oil is gone now, so we're living on 20-1 EROEI and declining quickly. Renewables give a roughly 3-1 eroei. Think about all the things civilization will have to prioritize to live on a 3-1 metabolism. Monster truck rallies, NASCAR and Jetset NBA teams flying around the country eating beef hamburgers served via drive-thru (sic) to your SUV is gonzo.

A sustainable world leaves 50% of land in a state of nature, untouched by human hands to preserve biodiversity. The number 1 occupation is permaculture gardiner/farmer and we live in ultra low energy passivehouses. Everyone eats local and transport of goods is done only by sail. No more fossil fueled powered combine harvesters.

As our micro and nano plastics crises is showing us, we would have to give up synthetics like polyester for clothing. Whatever population we have would be wearing cotton, wool, hemp and leather or their birthday suit. No more single serving anything.

I could go on, but you get the idea. How many humans can be supported depends on the consumption of resources allowed by society and the equality permitted within that society. There is no exact number as there are a ton of variables.

A mostly equal society living a comfortable but austere lifestyle could probably support 1 billion which is roughly dialing back life to before the industrial revolution. Say 1800's While the planet is much degraded since then you could argue the number is much lower, but we have a lot more knowledge and skill today about chemistry, medicine, sanitation etc.

At the same time, are we still running MRI's in modern hospitals? What kind of pharmaceuticals can be run sustainably when your average person is a permaculturist farmer. There will naturally be some specialization. Will we choose doctors or soldiers? Do we have a militaries and political factions? That will consume an enormous amount of our sustainable energy and materials budget, thus fewer lives can be supported withing your sustainability budget.

In my personal opinion, 500 million or less would be optimal.

So, without animal products, the answer is yes. with animal products the answer is no, then we're way over the sustainability threshold. It is so inefficiënt and costs so much land and resources that the argument that the wealthy are hoarding resources is looking merely like a small problem in comparison.

Besides. Would humanity ever actually be happy and fulfilled when millions of animals have to suffer to get there? I would argue, not actually, not on a deep level. Superficially, perhaps.