What's the ideal population for the Earth?

U.S. 310,755,638
World 6,897,823,641
(14:13 UTC (EST+5) Feb 04, 2011)

Objectively, I think that maybe… 280,000,000 for the US would be better, and for the world, maybe 800 million less. But I don’t know for sure. I know that in the more densely populated places (China) that it would be better if they weren’t all in the same place. That can’t be healthy.

It would vary based on the technology to grow/produce food we have. Speaking specifically with space, we could probably have many trillions of people on the planet. Feeding them all becomes the issue. But technology is overcoming that as time goes on. Without modern pesticides, genetic treatments, etc…. our agriculture would never support the 6 billion plus we have right now. The world of 1400, couldn’t support our current population. That technology will probably continue to expand… hopefully at a rate that can keep up with our population.

One that maximizes our ability to survive into the far future while maintaining an ever-increasing quality of life. For me, personally, that would probably mean going back to a population size like the one back in the 1950s. There would be a lot more shore line available, and you wouldn’t be tripping over a body every foot you traveled on the beach.

From some clips I watched in my bio class last semester, scholar’s estimates ran from 500 million to 3 billion. But there’s more to the question than just population. Things like the Ehrlich equation provide interesting factors to look at.

Anything over one billion is too many. The Earth’s resources are limited.

Overpopulation is irrelevent without talking about (over-)consumption. We could have a bajillion people if nobody ate, stood, or shit anywhere.

The actual number varies depending on the efficiency of the distribution of the available resources.

To really address this, we need to not only look at how many people we can feed, but how we are feeding them. Unsustainable food production is a major cause for many droughts, since they deplete soil and contribute to desertification. The basis of unsustainable food production is monocropping, though now monocropping is being used to bolster the even more destructive practice of factory farming. The practice of monocropping caused the Dustbowl in the last century, and is responsible today for the use of so much chemical fertilizers, which along with chemical pesticides and mass irrigation, are responsible for massive soil loss. The inevitable result of such practice unfettered is population crash.

It’s also an innefficient way to produce food, in terms of space/output. Complex multi-level polycrops, like those created through permaculture (in imitation of natural cycles and indigenous land “management” techniques) on the other hand, create the most food per acre. But corporations and other centralized powers can’t easily control that sort of food production, as it can’t be gathered by machines and is characteristically more democratic in application. If we were to cut out the corporations controlling our food (98% of the American food supply is controlled by only a few corporations), and grow our food using methods that build more soil (companion planting, permaculture, pasturing livestock), we might have a chance.

The ideal population is not a number, but a function of civilization’s level of technological advancement.

Here’s one example for such a function:

http://en.wikipedia.org/wiki/Kardashev_scale

I’d say our current level of 0.72 is not enough to sustain 6.9 billion people, so right now there’s overpopulation. But a level of 0.85 might be enough to sustain 8 billion people. So the challenge is to drive up the level faster than our current population growth rate. The key are renewable energies and recycling of rare metals (cradle to cradle manufacturing).