A Model of Human Population Growth: Is a Breaking Point Coming?

[kendr_pind]

i was just wondering abt this thing for a while...
the total no. of human beings are increasing over the decades...which means some %ge of the Earth's matter is getting converted in the form of humans...suppose if the population goes on increasing, then theoretically there should be only humans floating in space and no Earth at all..i mean all the Earth's matter is converted into human material...im excluding animals & plants for simplicity...this may take billions of years...
now speaking practically, there shud be a point beyond which humans start fighting for the resources to sustain themselves and can no longer multiply...this obviously takes less time..can anyone tell when this point shall come...in 50yrs, 200yrs...? is there any model of the growth of human population which talks of such a point?

 

[billiards]

it's ecologically impossible for a population to grow to a size where the available energy is less than the energy required to sustain the population.

 

[kendr_pind]

correct...but i want to emphasize the fact that humans can't obviously live for ever..somewhere we might have to grow lesser and lesser..are the govts taking any step towards these...cos left at that i think this burn out point will come very soon...

 

[Phobos]

try this...
http://en.wikipedia.org/wiki/Carrying_capacity

Note that the carrying capacity also depends on the level of technology we employ. When humans were hunter-gatherers only, the Earth could only support a few 10s of millions of people. But with agriculture, the Earth can support billions. How many billions? I think we can only estimate at this point.

 

[DaveC426913]

If we don't make our way into space, and/or bring resources down from space - either way easing the burden on Earth - then we will eventually run up against a rate-limiting step for human growth This will occur long before we see any more obvious signs of Earth-erosion. This rate-limiting step will come in one of two forms:

- a deficit of some critical material (probably a rare element) our bodies need. http://www.davesbrain.ca/bio_davesatoms.php" .

- a surplus of some waste that we can't dispose of (which by definition is toxic). The most likely waste product that we will choke on is heat. Ultimately, any process we use, no matter how efficient, will ultimately produce heat.

 

[Astronuc]

Soylent Green is just around the corner.


Humans occupy a very thin layer and exceedingly small volume and mass fractions of the planet - a few meters on a planet that has a diameter of about 12,756.3 km - 12,765,300 m.

The pressure at the center of the Earth is about 350 GPa as compared to 1 atm or 0.101325 MPa.

 

[russ_watters]

correct...but i want to emphasize the fact that humans can't obviously live for ever..somewhere we might have to grow lesser and lesser..are the govts taking any step towards these...cos left at that i think this burn out point will come very soon...

Have you calculated how many people there would need to be before governments should care about this issue...?

 

[DaveC426913]

Have you calculated how many people there would need to be before governments should care about this issue...?

Less than 6 billion.

The point being, we are already running into rate-limiting steps. This can be verified by noting that the world's current population is not composed entirely of middle-class slightly over-weight families. On some parts of the Earth people are starving. Our population is advancing faster than our technology to support them.

(Granted, this is a bit of an oversimplification. It's not like Ethiopians were once thriving and their current starvation is due to population growth...)

 

[Astronuc]

Some of the problems in Africa stem from significant changes in weather patterns. East and S. Africa have seen signficant declines in rainfall during the past decade or so.

Parts of Africa have suffered from over-graising, decimation of forest areas (for fuel) and poor farming practices. That has begun to change, but slowly.

Australia is experience its worst drought in a century or more.

The central US (particularly the Dakotas, Montana, Wyoming, Nebraska) have been experiencing significant drought conditions.
http://www.cpc.ncep.noaa.gov/products/expert_assessment/drought_assessment.shtml

 

[russ_watters]

Less than 6 billion.

Did you read the OP? The OP is worried about the entire mass of the Earth being converted to people.

In any case, I think you are wrong about the Earth not being able to support the people it has. You basically gave the reason why you are wrong at the end of the post! You're right: the starvation in the world today is not due to overpopulation!

 

[DaveC426913]

Did you read the OP? The OP is worried about the entire mass of the Earth being converted to people. !

Yes. And in post 5 I pointed out why it wouldn't come to that. Nonetheless, the more practical problem of carrying capacity remains, which is what I'm addressing here. It's just that your post 7 comment came a little late in the discussion.

In any case, I think you are wrong about the Earth not being able to support the people it has. You basically gave the reason why you are wrong at the end of the post! You're right: the starvation in the world today is not due to overpopulation!

Yes, I'm modifying the OP's question to one that's a little more faithful to reality - that includes technology as well as varying levels of sustainability in different geographical parts of the world.

i.e pointing out that there's no functional difference between the world not having enough Calcium (for example) to build our bones - and the world not having enough technology to get that Calcium to its population.