World overpopulation

[Jebus]

Overpopulation is a major issue.

I agree.

It isn't, actually. Overpopulation in undeveloped countries is a major issue, because they don't have the infrastructure or resources to provide for them (healthcare, education, etc.).

Overpopulation in undeveloped countries is a big problem for the people in the undeveloped countries. Overpopulation in developed countries, like Singapore, is a world problem as they leave a huge carbon footprint.

We should easily be fine with well over 30 billion people if we start living more sustainably.

Yes, but that’s a big if so why take the risk? We may be able to support 30 billion people under current earth conditions, but I doubt we will be able to once we reach that number? Also, do you subscribe to Malthus law or why else do you think population growth will stop at 30 billion?
Furthermore, the fact that we hypothetically could support 30 billion people doesn’t take into consideration the following:
1. Civil unrest is more probable and has more severe consequences the higher the population gets.
2. Diseases will spread at a quicker rate.
3. People are generally happier when not feeling cramped by crowds.
4. The more people the higher the chance of getting one nutjob that will blow up the world.

the faster our population grows, the sooner we will be forced to start being more sustainable, and the sooner meat will not be an option for anybody anymore.

This is probably true although I would worry that animal welfare laws may be ignored or retracted, meaning that they would find ways of making bigger animals while cramming them into smaller places. Either way, the wealthy would still eat meat while the poor would probably try to hunt on their own (including fishing). No doubt that this could be an advantage though. However, it doesn’t come close to comparing to the disadvantages of overpopulation.

[brimstoneSalad]

Overpopulation in developed countries, like Singapore, is a world problem as they leave a huge carbon footprint.

It's something we need to work on, but it's better to focus on sustainability than lowering population.

How many carnists living flagrantly unsustainable lives have you seen argue, "meat isn't the problem, it's the human population"?
I maintain the opposite: It's not how many people are living, but how they are living (and meat eating is a big part of that harm).

Population growth is mainly an issue in the developing world, and that's not something we have much control over. What we can control is our progress in being more sustainable.

Yes, but that’s a big if so why take the risk?

Sustainability isn't such a big risk in the long run; we have the knowledge and technology to achieve it, it's a matter of policy, and when a "do or die" decision finally becomes evident, political forces will ultimately cave.

The bigger issue is the immediate threat of climate change, and that will mainly affect the developing world.
It's probably an unavoidable catastrophe, but having the best chance of avoiding it means promoting sustainability as hard as we can.

We may be able to support 30 billion people under current earth conditions, but I doubt we will be able to once we reach that number?

There are about 1.4 billion cows, at 1,600 lb each. Replacing cow biomass with humans alone (which would be drastically lower producers of methane than cows) as vegans would be another 14 billion easily. We can add about another four billion replacing the biomass of other livestock, but they also eat more and grow faster than fully grown adults do, so probably better than that.

Around 30 billion is a pretty safe guess. People will have to not eat animals, and we will have to switch entirely to nuclear power.

Also, do you subscribe to Malthus law or why else do you think population growth will stop at 30 billion?

Projections I've seen have it leveling off before that.
But again, population growth is mainly an issue for poor countries. I'm all for distributing condoms and sex education there when possible, but I'm not sure how effective that is compared to advocating sustainability. For vegans, I think our best approach is to focus on sustainability and plant based diets at home; friends, family, neighbors, and people on the street or who we communicate with on the net.

Furthermore, the fact that we hypothetically could support 30 billion people doesn’t take into consideration the following:
1. Civil unrest is more probable and has more severe consequences the higher the population gets.
2. Diseases will spread at a quicker rate.
3. People are generally happier when not feeling cramped by crowds.
4. The more people the higher the chance of getting one nutjob that will blow up the world.

Good things and bad things both that derive from human population are more probable. We also get more geniuses, more scientists, more people getting together to do good.

1. Civil unrest is mainly an issue of economics and dogma; this is mainly a correlation issue with population growth due to poverty. Education and political and economic reform fix both.
2. Diseases spreading depend on population density and movement, but also on hygiene. Ending animal agriculture will go a long way to fighting superbugs and zoonotic diseases. Better protocols for controlling disease and responding to it quickly with vaccines will have to be developed, but there will also be a larger demand for that, and more advanced biotechnology.
3. There's no need to be cramped by crowds in a city; Asian cities can be very densely populated, but still maintain foot traffic control, and provide ample living space through tall apartment complexes and large malls.
4. I don't think a single nutjob can blow up the world.

This is probably true although I would worry that animal welfare laws may be ignored or retracted, meaning that they would find ways of making bigger animals while cramming them into smaller places.

Thermodynamics is a bigger issue. The resources just won't be there.

Either way, the wealthy would still eat meat while the poor would probably try to hunt on their own (including fishing).

Sure, the very wealthy might, but it's a far cry from what he have today. The very wealthy can eat humans if they pay for it; there's no stopping unethical money from engaging in the black market and absurd luxuries.

Most of the poor will not hunt; there's not much to hunt in cities, which is where most people will need to live.

[Jebus]

It's not how many people are living, but how they are living (and meat eating is a big part of that harm).

They are both huge problems

Population growth is mainly an issue in the developing world, and that's not something we have much control over. What we can control is our progress in being more sustainable.

I disagree. I think educating poor people and giving them affordable birth control methods is easier than convincing people to stop eating cows.

Sustainability isn't such a big risk in the long run; we have the knowledge and technology to achieve it, it's a matter of policy, and when a "do or die" decision finally becomes evident, political forces will ultimately cave.

But by the time they do an enormous number of suffering has already taken place. Imagine the lives that have come and gone between the five billion people and the 30 billion people mark, and imagine how many animals those people have killed. It might take hundreds of years before the steady five billion carnivores catch up.

The bigger issue is the immediate threat of climate change, and that will mainly affect the developing world.

I don't know which one is bigger. They are both huge and they both affect each other. At first population growth will speed up climate change while later climate change will control the population.

It's probably an unavoidable catastrophe, but having the best chance of avoiding it means promoting sustainability as hard as we can.

Yes, and by promoting population control as hard as we can.

There are about 1.4 billion cows, at 1,600 lb each. Replacing cow biomass with humans alone (which would be drastically lower producers of methane than cows) as vegans would be another 14 billion easily. We can add about another four billion replacing the biomass of other livestock, but they also eat more and grow faster than fully grown adults do, so probably better than that.

I agree and this probably debunks my soil depletion point. However, I can think of other environmental reasons we don't want to wait with policy change until we are at 30 billion people.

I'm all for distributing condoms and sex education there when possible, but I'm not sure how effective that is compared to advocating sustainability.

One doesn't exclude the other. They are both critical.

Good things and bad things both that derive from human population are more probable. We also get more geniuses, more scientists, more people getting together to do good.

This reminds me of another discussion we had a while back where you were optimistic about the future while I was a pessimist. Looking at history and human nature, I see no reason to believe why these people would get together to do good and not bad.

Civil unrest is mainly an issue of economics and dogma; this is mainly a correlation issue with population growth due to poverty. Education and political and economic reform fix both.

In the future I think civil unrest will have lots to do with climate change. Also, I think it will be easier for people to get irritable if they never have privacy, i.e. they live in an overcrowded area.

Diseases spreading depend on population density and movement, but also on hygiene. Ending animal agriculture will go a long way to fighting superbugs and zoonotic diseases. Better protocols for controlling disease and responding to it quickly with vaccines will have to be developed, but there will also be a larger demand for that, and more advanced biotechnology.

It seems you agree that all other factors being equal, there is a positive correlation between disease and population growth.

There's no need to be cramped by crowds in a city; Asian cities can be very densely populated, but still maintain foot traffic control, and provide ample living space through tall apartment complexes and large malls.

This is somewhat true for wealthier cities like Tokyo and Singapore, but entirely untrue for Bombay and Delhi.

I don't think a single nutjob can blow up the world.

We already have tennis ball sized nuclear weapons. What's not to say that these will get more powerful in the future? Either way, the more the people in my local neighbourhood, the bigger the chance of someone blowing up my local train station and there is no way more security guards can ever make up for that.

[miniboes]

I disagree. I think educating poor people and giving them affordable birth control methods is easier than convincing people to stop eating cows.

Lack of education and birth control is not the main cause of the huge population growths we see in developing countries, however. It helps, sure, but other factors are more important. Child mortality seems to be a very important cause, along with a lack of economic security. If people are dependent on children to support them, they will have as many children as they need to secure the support they need. If children die a lot, they will have more children so they can afford to lose some. The most important thing to take care of, as I understand it, is to make sure two people can provide for themselves as long as they are active. Also that they can provide for 1-3 children for 18+ years and have a secure retirement. Allowing women to enter the workforce is an important step.

The bigger issue is the immediate threat of climate change, and that will mainly affect the developing world.

I don't know which one is bigger. They are both huge and they both affect each other. At first population growth will speed up climate change while later climate change will control the population.

I think you are right here, they are very much connected. It is also arguable that a part of a sustainable lifestyle is not having too many children. If that is true, then we are talking about one and the same issue of sustainability, which climate change and population growth are both a part of.

It's probably an unavoidable catastrophe, but having the best chance of avoiding it means promoting sustainability as hard as we can.

Yes, and by promoting population control as hard as we can.

Indeed, these actions are not mutually exclusive. I find how you phrase it confusing, however. 'Promoting population control', what does this mean? I would simply call it limiting population growth. This can be done in a number of ways. Promoting population control seems to imply policies like China's one-child-per-couple policy.

I'm all for distributing condoms and sex education there when possible, but I'm not sure how effective that is compared to advocating sustainability.

One doesn't exclude the other. They are both critical.

One is a much larger task than the other, and I think you can guess which is which here. Also, as I have stated, I think condoms and sex education are only a small part of limiting population growth. I think general, sustainable economic and social development has a much larger impact.

Good things and bad things both that derive from human population are more probable. We also get more geniuses, more scientists, more people getting together to do good.

This reminds me of another discussion we had a while back where you were optimistic about the future while I was a pessimist. Looking at history and human nature, I see no reason to believe why these people would get together to do good and not bad.

I don't think brimstone is arguing that people will only do more good. I think his point is that people will continue to do both good things and bad things. I do think along the course of history the good things we do gradually increase, whilst the bad things decline. Veganism is just the latest of many moral developments.

In the future I think civil unrest will have lots to do with climate change.

Definitely. Climate change → food scarcity → unrest.

Also, I think it will be easier for people to get irritable if they never have privacy, i.e. they live in an overcrowded area.

I don't think there's much evidence for this. It seems improbably that every place will have the population density of New York, and people in New York don't seem to have a very terrible time.

We already have tennis ball sized nuclear weapons. What's not to say that these will get more powerful in the future? .

Can one man make such a weapon and use it? It seems highly unprobable.

Either way, the more the people in my local neighbourhood, the bigger the chance of someone blowing up my local train station and there is no way more security guards can ever make up for that

a) Of your local train station and the world, one is significantly larger.
b) How are you sure that chance increases? For example, there might be more social control and/or cohesion, decreasing the probability.

[Jebus]

Child mortality seems to be a very important cause

Improved child mortality has sped up population growth.

If people are dependent on children to support them, they will have as many children as they need to secure the support they need.

Yes, and this is where policy and education is crucial. Policy in order to give the elderly an alternate source of income and education so that people understand the whole picture.

Indeed, these actions are not mutually exclusive. I find how you phrase it confusing, however. 'Promoting population control', what does this mean? I would simply call it limiting population growth. This can be done in a number of ways. Promoting population control seems to imply policies like China's one-child-per-couple policy.

Promoting population control" will lead to policies that "limit population growth." Such policies could include education programs, removing tax breaks or contributions, or China style limitation policies.

"I do think along the course of history the good things we do gradually increase, whilst the bad things decline.

This is generally true over the last 1000 years or so but I doubt people will do many unselfish deeds in a world with food and water scarcity.

Also, I think it will be easier for people to get irritable if they never have privacy, i.e. they live in an overcrowded area.

I don't think there's much evidence for this. It seems improbably that every place will have the population density of New York, and people in New York don't seem to have a very terrible time.

I don't think there is much evidence either way. I'm just using observation and common sense. New Yorkers seem a lot more irritable than people from Old Saybrook.

[brimstoneSalad]

They are both huge problems

Population is only a problem due to our unsustainable and for carnists arguably net harmful behaviors as a species. Lacking those, I'd be glad to see a 30 billion population of happy vegans, enjoying life and working to make the world even better.
I would not be glad to see a population of a million environmentally sustainable but primitive warring tribes.

Pinker makes a number of compelling arguments about how the world is getting better:
https://www.ted.com/talks/steven_pinker ... anguage=en

Sure, there may be an odd million murderers and psychopaths mixed in with the 30 billion -- and maybe more -- but given that life is generally enjoyable to those who are subjects of it, I don't think the harm the bad apples do outweighs the good.

With a smaller and more primitive population still practicing harmful behavior, there's a much better chance that the harm does outweigh the good.
It's hard to overstate how terrible and brutal tribal societies are.

We paint a very slanted picture today of the cultural genocide done by Christian missionaries, but while they were spreading a flawed belief system, the civilization of Christiandom was a good thing for human beings. We just have a few more bits to dump (like the meat eating, the pseudoscience fear of nuclear power, and the more dogmatic religion).

I disagree. I think educating poor people and giving them affordable birth control methods is easier than convincing people to stop eating cows.

I think Miniboes responded to this well. That helps a little, but I think it's of limited utility if we don't correct the underlying socioeconomic issues. So, I don't think it's easier than stopping people from eating cows (or at least getting people to eat fewer cows as a step along the way).

http://www.animalcharityevaluators.org/ ... alculator/

About $1,000 offsets the harm to animals from one Western carnist. How many people in the undeveloped world would have to be prevented to have the same effect? How does harm compare? Will the same thousand dollars donated to an organization that distributes condoms prevent ten or so (how many is needed) people from being born in a developing country?

I also question the likely failure to account for the ripple effect, and concepts of critical mass in those statistics when looking at the benefit of vegan outreach.

But by the time they do an enormous number of suffering has already taken place. Imagine the lives that have come and gone between the five billion people and the 30 billion people mark, and imagine how many animals those people have killed. It might take hundreds of years before the steady five billion carnivores catch up.

I didn't mean to imply that the 30 billion mark was the "do or die" time. That's closer to the limit of the planet -- only reached well after everybody goes vegan, and we switch to nuclear power. We will never reach that mark unless we act long before that.

The next couple decades will be the deciding time.
We'll have in-vitro meat soon, and the effects of global warming are going to start bothering people who "matter" in this. It's going to become impossible to deny very soon.

I'm just saying that as long as we go sustainable, the actual population cap is far, far off, and it's only something to start worrying about seriously as we approach 30 billion.
IMO, based on my rough guess of advancing technology, improving agriculture, and energy technology, the Earth could easily support over 100 billion vegans living on nuclear power with better optimized agriculture and green infrastructure. That's a little more speculative, though. 30 billion is conservative.

I don't think population is ever going to be a serious issue for a conscientious and "green" civilization here on Earth. And that's assuming the technological singularity has nothing to say about all of this.

Yes, and by promoting population control as hard as we can.

I don't think that's as useful to prevent global warming, and the disasters it will cause. The developing world, where we can make the most difference promoting birth control, isn't anywhere nearly as responsible for the effects.

I think stopping one person in the developed world from eating meat will ultimately defer climate change more than stopping several people from being born in the undeveloped world.

One doesn't exclude the other. They are both critical.

In promoting anything other than a vegan message, there is an opportunity cost. If one means of activism is less effective, I don't think it's worth the time or energy as potential vegan activists to promote it instead, even for a minute, if it costs any time promoting vegan outreach.

This is why I don't spend much of my time on religious issues, for example; although there are cases where they interfere with sustainability goals, and there they need to be confronted.

In the future I think civil unrest will have lots to do with climate change.

If we don't stop it, sure. And that's also one of the things that will force us to change.

Also, I think it will be easier for people to get irritable if they never have privacy, i.e. they live in an overcrowded area.

Maybe, but what's this all mean in terms of harm? Can we make any estimates?

My guess is that global warming may ultimately be responsible for the deaths of a couple billion people.

It seems you agree that all other factors being equal, there is a positive correlation between disease and population growth.

More so global warming. There will likely be some serious pandemics.

This is somewhat true for wealthier cities like Tokyo and Singapore, but entirely untrue for Bombay and Delhi.

Which is to say, it's an economic issue more than a mere population one.

We already have tennis ball sized nuclear weapons.

Where are you getting that from?

Either way, the more the people in my local neighbourhood, the bigger the chance of someone blowing up my local train station and there is no way more security guards can ever make up for that.

There will also be more train stations for them to blow up. Population and infrastructure scale together, but if you look at large cities that are not impoverished, relative crime (whether that's blowing things up, rape, murder, robbery) is still quite low.

A higher population density does make an attack dangerous to more people, but we already have densely populated cities for terrorists to target. I don't think having more cities, or slightly larger cities (and terrorists perhaps still in the same proportion of the total population), really makes this more of an issue.

[Red]

Sorry to stray away from the discussion, but there's something I wanna bring up.

The Amazing Atheist made a shitty video about overpopulation that can be found here:
https://www.youtube.com/watch?v=WMJQnatcaZQ

Libertarian Socialist Rants did a pretty good job at refuting it, for the most part.
https://www.youtube.com/watch?v=fYxyuRarCGQ

One of my issues I have with Cameron is with his tool shed example. Since in capitalism, more resources are depleted due to more resources being used since people buy their own sheds But wouldn't that mean that the more people there are, the faster the resources are depleted (even in capitalism(if any of that made any sense))?

But whatever. I do agree that overpopulation can happen, but I also agree that we shouldn't be too worried int he first world, and I'm pretty sure we can manage to give everyone an equal amount of resources.




But that's just me.

[Jebus]

Population is only a problem due to our unsustainable and for carnists arguably net harmful behaviors as a species. Lacking those, I'd be glad to see a 30 billion population of happy vegans, enjoying life and working to make the world even better

You sound like an idealist here. X is only a problem if Y doesn't change. My position is that X is a problem because we don't know if Y will change and even if it does there will still be problems with X.

Pinker makes a number of compelling arguments about how the world is getting better:
https://www.ted.com/talks/steven_pinker ... anguage=en

I thought he could have simplified the reason why people think violence is on the rise by saying that they don't know history. I also think he could have mentioned that the reason for less violence is lower importance of religion and lower food scarcity.

Sure, there may be an odd million murderers and psychopaths mixed in with the 30 billion -- and maybe more -- but given that life is generally enjoyable to those who are subjects of it, I don't think the harm the bad apples do outweighs the good.

I disagree with this for two reasons. First of all, the more crowded the place the easier it gets to kill and injure lots of people in one go. Also, the progression of weapons throughout history have made mass murder on the hands of one person easier and I expect this to continue. Pakistan claims to have tennis ball sized nukes although this has not been proven. It is however not technologically impossible.

About $1,000 offsets the harm to animals from one Western carnist. How many people in the undeveloped world would have to be prevented to have the same effect? How does harm compare? Will the same thousand dollars donated to an organization that distributes condoms prevent ten or so (how many is needed) people from being born in a developing country?

One should be careful not to presume that the climate affecting habits of the underdeveloped world will remain as present. Look at China as an example. While their population exploded in the mid 1900s there was little concern of environmental impact. However as the economy improved they all began eating meat, driving cars, and buying air conditioners.

the effects of global warming are going to start bothering people who "matter" in this. It's going to become impossible to deny very soon.

It should have been impossible to deny years ago. The problem is that people are religious and they will most likely continue to be religious. Hence, it's all in God's hands so no behavioural change is needed.

In promoting anything other than a vegan message, there is an opportunity cost.

I disagree here too. Perhaps you are in a better position to promote veganism than Merkel and Obama (since we are vegan) but others may be better off promoting having fewer children. I don't think the opportunity cost principle applies here as how I will spend my time depends largely on which situation I am in. Let's say I'm in a room with a friend who is thinking about having kids and who has already heard me promote a plant-based diet many times. Would it be better if I spend the next five minutes talking about population control or veganism?

It seems you agree that all other factors being equal, there is a positive correlation between disease and population growth.

More so global warming. There will likely be some serious pandemics.

I agree although I think you dodged the question.

This is somewhat true for wealthier cities like Tokyo and Singapore, but entirely untrue for Bombay and Delhi.

Which is to say, it's an economic issue more than a mere population one.

Improve the economy or drop the population. Both would help.

I'd like to draw your attention to the fact that the population is growing in the Western developed world as well and this would be true even if there were no immigration. How is this not a problem? Each additional person gives an estimated 97% increased chance (probably more as vegans have fewer kids) of causing animal suffering using up an unfair share of the world's resources. I understand your position that population growth may ultimately lead to more sustainable habits but I think it will be too late by the time we make that realization.

[brimstoneSalad]

My position is that X is a problem because we don't know if Y will change and even if it does there will still be problems with X.

I'm saying if Y changes, X isn't a problem at all. And Y has to change because X will force it to change. If not X, then Y may never change, and that's an even bigger problem. And I don't necessarily think we can do very much about X (we can only most effectively control our own actions, and our children are part of the solution, not part of the problem).

If we effectively control our broader population, or reduce it, humanity may be able to continue factory farming and harming animals indefinitely, and will never be forced to advanced beyond that point.
Keeping the poor in poverty doesn't seem like a solution either, it seems like perpetuating a problem to avoid a short term struggle.

Better we have a short term problem, and then for the next couple billion years a larger happier world.

I disagree with this for two reasons. First of all, the more crowded the place the easier it gets to kill and injure lots of people in one go.

Sure, but my point is that we already have enough crowded places to go around for all of the crazy people. Currently, not all crowded places are being exploited by madmen. The lack of mass violence is not for lack of crowded places, but for lack of the competent evil people to exploit them.
Adding more crowded places doesn't mean exponentially more violence -- I would only expect it to grow linearly with the population, or even less. It would be a better argument if currently all very crowded places were being exploited and there was a real demand for more among nut jobs.

Also, the progression of weapons throughout history have made mass murder on the hands of one person easier and I expect this to continue. Pakistan claims to have tennis ball sized nukes although this has not been proven. It is however not technologically impossible.

I don't believe that Pakistan has tennis ball sized nukes, or that such devices are possible with current technology.
Those rumors are probably referring to the pit, which is not the weapon itself but merely the fissile material and its immediate containment:
https://en.wikipedia.org/wiki/Pit_(nuclear_weapon)
Nuclear weapons require too much conventional explosive to detonate to miniaturize that much: energy density is an issue.

There are physical limits, and those imposed by the basic laws of physics, that define how small a weapon of a certain magnitude of destruction can be.

Yes, growing technology may make it easier for crazy people to harm more people (biotechnology is actually much more of a threat than nuclear), but it also gives more tools to law enforcement: I don't agree that it does more harm than good, or necessarily makes the world more dangerous. More geniuses are benevolent than evil, so I think technology is overall on the side of good.
If that were the case, though, it would be an issue with technology, not with population itself. As I said above, not all high density areas are taken advantage now: I don't think there's a shortage of targets. Devastation from technology would grow either way (and has plenty of room to grow as is).

Also, I don't see nut jobs like Islamists are serious threats, because they're ignorant and mostly technologically incompetent (good luck finding one who believes in evolution, much less one who can use evolution to create a bio-weapon).
The O.O.S. crowd is a different matter.

One should be careful not to presume that the climate affecting habits of the underdeveloped world will remain as present.

They likely won't, but won't that just force us all to change faster if they do?

It should have been impossible to deny years ago. The problem is that people are religious and they will most likely continue to be religious. Hence, it's all in God's hands so no behavioural change is needed.

We may need to wait for more of those people to die off.

https://www.washingtonpost.com/news/won ... te-change/

I disagree here too. Perhaps you are in a better position to promote veganism than Merkel and Obama (since we are vegan) but others may be better off promoting having fewer children.

If somebody is not vegan, that person should go vegan of course, and promote that. Meat reduction may even be a more effective message in practice, and people may receive it better from those who eat meat too (since they'll be more open to the message).

But if that person is delusional and won't go vegan or reduce meat consumption and incorrectly sees no value in it, is it better that he or she promote population control in the developing world? Maybe. That, of course, is not us.

I don't think the opportunity cost principle applies here as how I will spend my time depends largely on which situation I am in. Let's say I'm in a room with a friend who is thinking about having kids and who has already heard me promote a plant-based diet many times. Would it be better if I spend the next five minutes talking about population control or veganism?

I think it would still be more effective to promote veganism; try another angle. Keep planting that seed and encouraging change.
Focus on the children and the next generation, and how we need to save the Earth for them, and provide a good example.

I agree although I think you dodged the question.

All other things being equal -- but I don't think all other things will be equal, or that it's useful to evaluate population control in those terms because it forces certain other structural changes.

It's like saying, all other things being equal, tripling the population would mean maximum occupancy would be exceeded for apartments, which would be a fire safety hazard, and subways would be over-full and nobody would be able to get to work, and 2/3 of the population would have no work to do. Sure, but infrastructure would expand with population, including employment, transit, and apartments. As disease risk increases, the CDC and other organizations will also expand non-linearly in influence (because that's what's needed), and we'll see more advanced screening for travelers, and more widespread vaccination programs. Instead of being prodded by the TSA, you'll be prodded by the CDC, and we'll see biological swabs and rapid blood screening (technology will enable this; it's already possible, we just need the demand to make it widespread, and nothing stokes demand like necessity).

I'd like to draw your attention to the fact that the population is growing in the Western developed world as well and this would be true even if there were no immigration. How is this not a problem? Each additional person gives an estimated 97% increased chance (probably more as vegans have fewer kids) of causing animal suffering using up an unfair share of the world's resources. I understand your position that population growth may ultimately lead to more sustainable habits but I think it will be too late by the time we make that realization.

Well, vegans need to have more kids, and otherwise exercise more influence too. As it becomes easier to be vegan, I think we'll reach a critical mass.
We also need to not be lax in our outreach to other parts of the world. For example, maybe we should be reaching out to China more, and helping Chinese vegans spread that message there. And even Africa and India.

It may be "too late" for the couple billion who will die as a consequence, but after that we should be able to get it right and the next few billion years (which will make up the vast majority of our life as a species) could be much better after those growing pains.
If we focus on reducing population instead of sustainability and compassionate lifestyle, I think we're focusing on the wrong thing in the long run, and the consequences to that could ultimately be a lot worse (even if we succeed, which I don't think we will since I think population control is pretty futile, but vegan outreach is not).