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[LordBucket]

See my thing about breathing.

I was in before your edit.

that 7 trillion assumes wall-to-wall global solar panels over the entire planet, at 100% efficiency

No, it assumes wall-to-wall global solar panels at 50% efficiency.

In any case, it was your scenario, not mine, so I used your numbers. If I were to examine the problem I would probably go about it a different way. Wall-to-wall solar panels seems impractical to me.

btw the oxygen-consumption figures are for "at rest" people. So obviously it's LOW

Ok, but if you're proposing construction on the scale of global wall to wall solar panels, or an earth-encompassing Dyson Sphere, then artificial maintenance of the atmosphere doesn't seem at all like an unreasonable thing to go along with it.

[Reelya]

 :)You're free to come up with something, need an energy source and a big carbon sink. Plus there's the fact that at least 33000 people will live in each sq km. Let's say we pack 250,000 people per sq km so that we don't destroy the entire ecosystem while we're at it.

While i said "solar panels" that's not necessarily the literal technology, those are an estimate of the energy requirements based on the current "American" per capita consumption, and data on the total solar energy available. To collect all the solar energy you must necessarily intercept it so that plants cannot get it.

Maybe if we live in 10km tall, 40km across hives holding a 1 billion people each we can cut total energy requirements down due to low thermal losses. Hell our problem will be heat dissipation.

[LordBucket]

510,072,000 sq km. * 29.2% land (assume we want to leave the oceans intact) = 148941024 sq km. Divide 5 trillion people into this gives 33570 people per square kilometre. FOR EVERY INCH OF LAND. Forget EVER walking on the ground again. that's ~30 sq metres of surface per person.

Already addressed. Space is three dimensional. High rise buildings are not fantasy technology.

Also...

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

Your 33,570/km^2 is considerably less than some cities we already have. Manila has 43,079/km^2 and I highly doubt it's illegal to walk on the ground there.

[Reelya]

But that's the average density for every square inch of the land surface of the world. To achieve EVERYWHERE being Manila would destroy the environment. Or, assume 10% of the total land area covered in high-rises apartments as acceptable, and you're talking 330,000 per sq km.

btw google people's impressions of Manila.

http://www.huffingtonpost.com/2012/05/03/manila-slum-walls-built_n_1474363.html

They have walled-off slum hellholes. I really don't want to live in Necromunda.

"About a third of Manila's 12 million residents live in slums, and a third of 94 million Filipinos live below the poverty line of $1.25 a day."

[LordBucket]

But that's the average density for every square inch of the land surface of
the world. To achieve EVERY being Manila would destroy the environment.

This is the problem of having discussions like this with people. When they're shown that one problem they bring up is not really a problem, they change tact and move on to something else. And 2-3 pages later people will have forgotten about problems that have already been resolved and bring them up again, resulting in a never-ending cycle.

"Pollution" is only a problem of our current ways of doing things using our current assupmptions based on what's practical right now. Suggesting that we "can't" build up the rest of the planet as densely as our cities because of pollution isn't really all that different from somebody a couple hundred years ago claiming that modern cities would be impossible because...what would you do with all the shit from the horses?

The answer is obvious: don't create it in the first place.

"About a third of Manila's 12 million residents live in slums, and a third of 94 million Filipinos
live below the poverty line of $1.25 a day. Overall, more than half the population in Asia remains poor."

What does this have to do with anything? Make up your mind, please. Are you claiming that trillions of people on earth is not possible, or are you claiming that it is possible, but you wouldn't personally want to? Because I don't want to address your sudden interest in problems of poverty only to have you forget it and bring up something totally else a few pages from now.

[Reelya]

Hold up i didn't even reference "pollution". at ANY time. I'm not changing tack at all, you still haven't answered my first criticisms.

- energy will need to be collected - hence interdicting energy which normally goes to plants. I showed that pretty much the entire solar output that hits Earth would be required to maintain current Western usage per capita. Which is realistic since we'll be living in previously inhospitable places like all over the Sahara desert and Antarctica, so plenty cooling, heating and water pumping / purification will need to be powered, even if we get much more efficient.

- even at the current density of the densest city, the ENTIRE land surface will be taken over by cities, hence destroying all ecosystems. Well, logically we could destroy all biomes and replace them with cities, but is this a good idea?

- the combined humans will breathe out 1200 gigatons per year of carbon dioxide AT REST. Fix that one. Oh, but we just interdicted the entire solar output for our "lifestyle maintenance", yet we ALSO need to increase plant photosynthesis worldwide several times higher.

Why aren't you addressing any of these?

[LordBucket]

Why aren't you addressing any of these?

Because...

energy

1) The energy issue was already discussed 3-4 pages back. Like I said, we're doing a round-robin right now of complaining about one problem then the next, until people forget about problems that have already been discussed, creating an illusion of a never-ending cycle of problems. Remember, the solar panel scenario was your idea, not mine. I have no particular attachment to using your solutions just for the sake of you listening to you complain about the problems that accompany your solutions.

even at the current density of the densest city, the ENTIRE land
surface will be taken over by cities, hence destroying all ecosystems.

2a) I DID address population density, and you ignored me and swapped tact to start complaining about poverty.

2b) You're blind assertion about "destroying the environment" honestly sounded pretty weak to me. Rephrasing it now to "destroying all ecosystems" sounds just as weak. If you want me to address that, you're going to have to go into more detail as to what the hell you're talking about...because the entire premise we're talking about...building cities cross the earth...would pretty much by definition "destroy" the natural environments when we replace them with cities. I assumed you were talking about pollution...but now you're insisting that:

Hold up i didn't even reference "pollution". at ANY time.

So since you're not talking about pollution, what the hell are you talking about when you say destroying envioronment and ecosystems? Yes...building a city in the space that used to have a forest causes the forest to longer be there. And your point is what exactly?

carbon dioxide

3) You retroactively edited your post after I responded to it. I was not "ignoring" it. You added it in later. Check the timestamps. However, I did provide a quick, brief followup in this post pointing that artificial maintenance of the atmosphere would be reasonable thing to go along with your proposal of wall-to-wall solar panels. If you want we can talk about it in more detail, but since you edited it in as an afterthought I didn't really think it was necessary to go out of my way to address it.

[Reelya]

You still haven't explained an energy source which can do the job. If not solar, what? I guess we could beam it in from space mirrors, but then you have heating issues.

I mentioned ONE thing about severe poverty in Manila as an aside, since you brought up Manila as a great example of high-density living, and you keep misconstruing it as a main argument point. Let's drop that.

The point about cities destroying the environment is that 1000 times the current population would entail covering the entire world's non-ocean with 1 big city, or at least converting the entire surface to solely meet our needs. Bye bye to all existing eco systems.

My main point is that from at least 3 different aspects - energy needs, population density/urban coverage and human respiration O2 => CO2, there's no way to sustain that many people without severely completely disrupting the existing environment.

You 'solution' of total bioengineered atmosphere technology to deal with the 1200 gigatons of CO2 we would breath out just emphasizes the point.

[LordBucket]

You still haven't explained an energy source which can do the job. If not solar, what?
I guess we could beam it in from space mirrors, but then you have heating issues.

I've spent the past hour doing math on this, it's about two pages...and well beyond the tedium of what I could reasonably expect you to read. If you're willing to just accept my conclusions rather than expect me to reasonably format a legible explanation of how they were derived, we get the following end result:

1) The US is notoriously inefficient and is a poor choice of model for a futuristic society. Let's use Japan as a model instead of the US. It's more modern, yet nevertheless consumes half as much energy per person

2) Previously provided numbers appear to be off by a factor of about 4. I get:

Earth receives:
8,646,597,720,000,000 gigajoules per year from the sun

The energy consumption of 7 trillion people living a Japanese lifestyle rather than a US/derived/assumed lifestye:
1,187,900,000,000,000 gigajoules per year

That's 13% of what earth receives from the sun. Not the 50% or 100% that were proposed earlier. I realize there's a great deal of room for error in this kind of thing. Converting joules and watts and scientific notion to long form, the significance of rounding off at one point being exacerbated after multiplying by millions and billions later...etc. If anybody can provide a more reliable estimate that doesn't involve me spending more hours examining the question, I'm willing to look at it. But...these were the figures I came up with based on available data, making what I considered to be fairly reasonable assumptions, and the final result was considerably larger than I expected.

If you're willing to accept that figure, we can proceed from there to figure out how to generate that much energy. I think it can be done.

I mentioned ONE thing about severe poverty in Manila as an aside, since you brought up Manila as a great example of high-density living, and you keep misconstruing it as a main argument point. Let's drop that.

Ok. Dropping population density as a problem.

The point about cities destroying the environment is that 1000 times the current population would entail covering the entire world's non-ocean with 1 big city, or at least converting the entire surface to solely meet our needs. Bye bye to all existing eco systems.

...again...why is this a problem? I agree that if you build a city over a natural environment, you lose the natural envirorment. But I don't see that as a good argument against building cities.

Or is this a purely aesthetic consideration?

O2 => CO2

Scale of the problem
According to your own numbers, nature produces 25 much times as much carbon dioxide as human civiliztion does. A 1000 times increase in human population, assuming current levels of CO2 output, would result in a net of increase of 40 times the current "natural" output.

However:
http://micpohling.wordpress.com/2007/03/27/math-how-much-co2-is-emitted-by-human-on-earth-annually/

Between 91% and 94% of that CO2 production caused by humans is produced by the use of fossil fuels. So...stop burning fossil fuels. No more coal. Use electric cars. Use solar/wind/geothermal/nuclear/etc. energy sources. Simply using different technologies than the ones we happen to be using now, and our CO2 emmissions can be reduced by roughly a factor of ten.

So...instead of a 40x increase in net Co2 production with 7 trillion people we have have a 4x increase with 7 trillion people. At this point it would be easy to cheat. 7 trillion was an arbitrary choice for simplicity of math. My original claim was "trillions." I never specified how many trillions. The specific figure of 7 trillion came as a result of your statement in this post about multiping current population by 1000.

If we say 2 trillion instead of 7, that 4x increase becomes a 1.14x increase. Just more than double current levels. Not that big of a deal. Easily within our ability to absorb.

However...if we do decide to stick with the 7 trillion figure, a 4x increase in CO2 output is still easily within reason to suggest that we could accommodate it.

1) It's not necessarily even an issue. Obviously the human race didn't die off from carbon dioxide poisoning when we went from 1 billion to 7 billion people. Nor did it die off from carbon dioxide poisoning when we started producing ten times as much due to industrialization. The natural system has already demonstrated a large ability to adapt. At present, I think we lack any data to show us how much increase there would have to be before it created any major problems. It's possible the system could absorb a 4x increase without any direct intervention from us at all.

2) Plants (and algae especially) metabolize carbon dioxide. If you do need less CO2, then simply  grow more of them.

Now, I can already hear you eagerly getting excited at the chance to shoot this down because of lack of space. After all, we're building a city everywhere. But this was already addressed here:

"...there are three dimensions for us to work with. There's a LOT of available space if you simply go up or down. And incidentally there's nothing stopping us from using that vertical space for things other than storing people. You can grow food in the z-axis and build parks and pools and anything else you want up there too. There's no reason to build exclusively at surface level."

3) http://en.wikipedia.org/wiki/Algae_bioreactor

http://www.youtube.com/watch?v=yWBBJgKkqjI

Give them CO2. It makes them happy and they give us oxygen.

4) Your 7 trillion figure assumed only using the available land. That leaves the remaining 70.8% of the earth's water surface area...and incidentally quite a lot of volume. Good place for algae.

[Frumple]

Th'poverty's actually a pretty good point. Rough searching is showing that the poverty level in Japan was around 16% of the population in '09 (going by the government figures, near as I can tell). Jack the raw population that applies to up. Hell, lowball it to 10% and then apply it to a concentrated population in the tens of billions (or much lower. Say 100 mill!).

Wanna' know what happens when you have a sufficient number of destitute individuals concentrated in a particular geographic area? It's called societal destabilization and it freaking wrecks things.

Urbanized living, especially in supercities, is a problem with issues far exceeding those on the resource level. We can build the housing and we might be able to supply the power and food. That doesn't mean we're actually capable of supporting a serious increase in supercities, or that we're actually supporting the ones we have now (instead of, say, wrecking a bunch of other crap to keep them running). Population is more than a resource and engineering issue, and that "more" part isn't something I've heard much about fixing.

...again...why is this a problem? I agree that if you build a city over a natural environment, you lose the natural envirorment. But I don't see that as a good argument against building cities.

It's a problem because... y'know? The cities kinda' need a huge chunk of natural environment to support 'em, just like every other human endeavor. Environment as a whole needs th'robust ecological systems that currently only occur naturally if it's going to support human life. A sharp decrease in those robust systems (caused, say, by an even greater upswing in urbanization, or a even heavier increase in artificial monocultures) is one of the apocalypse scenarios that get bandied about when dealing with global warming and increased urbanization. There's actually pretty big issues with an extinction event, some of which that extend strongly into th'human arena. We're already violently murdering biodiversity to keep our cities running, and that loss isn't a trivial issue. Not further aggravating that problem is actually a pretty solid reason to try and slow the urbanization process.

To jocular things up a bit, we can technology it all up this in joint, m'fellow monkey boys, but at the end of the day we're still jumped up monkeys and we kinda' need the trees and th'more humble monkeys.

Or is this a purely aesthetic consideration?

This being another issue. I've seen a good chunk of stuff in passing suggesting that the "purely aesthetic" part of it's actually kinda' important, particularly in regards to human mental health and general stability. Might be something we could supplement via oversized parks or somethin', though.

[mainiac]

Why do cities need natural wilderness to support them?  We are no longer at a Malthusian technological level.  The question is how much you can farm artificially not how much food grows naturally.

The Japanese comparison actually highballs the amount of energy needed.  Even though Japan drives a lot less then the other places you can still knock that number down by 33% because of the very thermodynamically inefficient use of oil that represents 42% of their energy budget.  In this scenario such inefficiency isn't an option because there isn't any oil left so you can knock 33% off the energy use.

[Frumple]

Not. Just. Food. Is the simplest way of putting it. Artificial ecosystems are still, to the best of my knowledge, incredibly fragile compared to natural ones -- and even natural ones aren't particularly capable of withstanding the massive systemic shocks we've been repeatedly hammering into them. It... can't really be repeated enough: We're right smack in the middle of a massive extinction event. Impact from species loss goes well above and beyond the loss of just that species -- it impacts other species, it impacts plant life, and in some cases it can screw with shit right down to the chemical composition of the soil and water. We have't actually figured out how to offset that with artificial systems -- we're damn sure trying, but we don't have it and I'm entirely unsure when or if we will at any point in the future. Natural systems are incredibly complicated (which is one of treason ands they're as robust as they are) and, so far as I'm aware, we still don't understand the full consequence of their functions and functioning.

Cities are flatly reliant on stuff that those changes (which they're a heavy contributing factor to) slam right in to. Maybe we'll have the technology to help mitigate that in the future, but please excuse while I express doubt we're going to be able to magic things out of the aether anytime soon -- and until we're able to do that, we're still going to be reliant on natural ecosystems for resources and the health of those ecosystems are going to be a huge frakking issue impacting our ability to do that. Last I checked, we're not quite at the point we can just strip-mine and pave over bloody everything and build from base particles.

Anyway, it's a bit of a personal worry. Urbanization represents an absolutely incredible assault on a geographic region's environmental health, and it occurs (and has occurred) in a period of time so short that we're still not entirely sure exactly what the consequences of that assault are going to be, other than definitely negative (thermal retention is just one example I can recall off the top of my head; s'either LA or Las Vegas, iirc, that's actually fucking with the weather patterns around it due to pavement trapping heat.). I'm not quite at the point I'd say we wouldn't be able to engineer a solution to what's going down, but I would say that the urban areas we have look absolutely goddamn nothing like what we've currently got. Building future cities and -- possibly even more important -- rebuilding and upgrading the ones we have... that's not a small thing, to massively understate the issue, and it's not an issue just of money. Call it a worry, and feel free to reassure me, but I'm not sure how capable we are of meeting that sort of challenge.

Guess what I'm saying is not to underestimate just how big of an issue we're dealing with. It... even as complicated and advanced as the solutions we're providing now and will provide in the near future are, I still see them as not nearly as cognizant of the scale and scope of the problem they're attempting to solve as they need to be. S'an issue of scale completely and utterly unencountered in human history -- exponentially so, and even that may be underestimating just how large the problem is.

[mainiac]

If you are talking about a population of trillions of people then you are not talking about "anytime soon".  Many centuries if not a few millennia would be the better estimate.

[MetalSlimeHunt]

If you are talking about a population of trillions of people then you are not talking about "anytime soon".  Many centuries if not a few millennia would be the better estimate.

Try never. You'd have to start force breeding people once we hit 10 billion or so, because the growth isn't going to happen on its own.

[mainiac]

And you know this because?