Overpopulation isn't that of a big problem as the politics make it seem.
Of course this illustration is a simplification but it brings the world population back to perspective.
If there is a problem, it's water. On the plus side, water is the easiest to recycle by far, the only limit we're close to hitting in some locations is the amount of water that's recycled for free by the weather.
Also, we have skyscrapers. The 11m2 area per person is ground-level area. If you have 10-storey skyscrapers on average, 120m2 for every family on average should be easy, and allow for population to increase 5 fold without exceeding available space in Austria.
It's a complete speculation, because I can't cite this, but isn't Earth not capable of sustaining 7+ billion people? Exponential population growth brings even greater exponential rise of greenhouse effect, oil consumption, deforestation, etc. IMHO it is the main problem of overpopulation.
That's an Malthusianism[0] right here. Why recycling and increased efficiency themselves aren't a solution? Because people will increase their consumption to offset all the gains.
C.f.:
"Why are even some affluent parts of the world running out of fresh water? Because if they weren’t, they’d keep watering their lawns until they were."
It's not so much that overpopulation isn't an issue, of course it is (that's why it's called 'over' population), but rather that the trend line is that population growth is very rapidly slowing, that people tend to overestimate population growth, are unaware of big population centres that are shrinking, that the average worldwide children per woman rate is < 2.5 (used to be > 5 just 50 years ago) and that population will likely decline after we add a few billion more.
That's not to say that it isn't an issue, but traditionally we held some really weird views about overpopulation. Basically we looked at this graph: https://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Po...
and extrapolated the exponential growth, and ended up with scenarios of doom, war etc. Food shortages for example are consistently predicted, but food production growth has outstripped population growth substantially and food security is better than any time in the past (yet far from perfect).
Obviously there are huge sustainability concerns, but the biggest source is our level of consumption levels and patterns, not our population numbers, which comes in second.
Numbers of fanatically religious people will double, relatively speaking. Mostly Catholics and Muslims. This is under the assumption that the current rates of conversions remain roughly the same. Trouble is, people turn atheist, don't have kids, and die out, the number of atheists we have today is a historical anomaly resulting from the baby boom. In other words, that effect will stop. This likely will have policy implications.
People in cities are growing FAR slower than people in rural settings. That means that it isn't just atheists that will drop, but everything you associate with city living will lessen. Most city populations are essentially replaced with fresh people from rural settings every 60 years or so (meaning that the number of new rural people in the city at year+60 is larger than the number of people in the city).
Numbers of black people and asian people (not Chinese) will grow a hell of a lot more than the other groups. Africa should have 3-4 times more people than today at least before it stabilizes. Same goes for some countries in Asia. This of course also means that Europe is going to look back to today's Syrian "refugee crisis" and wonder why people were worried about a mere 1 million people per year.
Truth of the matter is that there isn't much any political movement in either Europe or America can do. So it doesn't even really matter.
As for an increase in non-white population, absolutely. But you seem to say it as some kind of issue. I don't care about skin color. A concern may be preserving a western culture, absolutely, but there the world has indeed westernised tremendously and shows few signs of slowing down.
I don't really share the sense of concern I interpreted (perhaps wrongfully) in your post.
> Truth of the matter is that there isn't much any political movement in either Europe or America can do.
The answer has always been obvious. It's a long-term answer, one not chosen for centuries. And it's called genuine cooperation and the desire for the rest of the world to rise up, become wealthy, prosperous and sensible, for us to yield some so the rest of the world can rise. Migrants have no interest in moving to where you do, if their own country is great. They have no interest in attacking you, if they're not oppressed or exploited by you. They've no interest in fanaticism if they have something to lose, and no enemy in sight, and an open hand shown to them. They have no need to bear 5 or 6 children if their healthcare system ensures all of them live. The world needs to do everything in its power to help developing countries if you ask me. Every country that has raised living standards has seen population growth decline. And the correlation between living standards and war/religiosity/fanaticism is negative, too. It's a moral imperative to help others, and research shows it helps ourselves, too. It's exactly the same principle why it makes sense for rich people to pay taxes to help the poor in their own country, because it improves their lives when the poor do better, when crime is reduced, and schools improve and roads are safe to drive on and homelessness is reduced and teenage pregnancies drop and schools get better etc etc. Imagine the rich in the US got private armies and lived in gated communities like in some areas in Brazil and walled off their tiny society, the US'd be a terrible country for all, same applies to Europe. Instead we build social democracies. Somehow we don't apply that beyond our borders much, at least not in the past few centuries, instead close our borders, sometimes exploit others beyond our borders, and when we see populations boom and signs of ill will towards us and see populations cling to a different culture than our own, we act surprised. We shouldn't be, it's the logical outcome of our foreign policy.
Protestants are the minority and they're viewed as the "fanatically religious people", people would say they're always talking about their religion, they don't party a lot, they don't drink alcohol and usually they have a lot of children, Mexico is a Catholic country and the average family has 2.2 children, but protestant minorities usually have more than 4-5 children.
I've noticed Americans apply some stereotypes to Catholics that would fit pretty well to the stereotypes protestants have in Mexico.
Maybe there's a correlation between minorities and the attachment to their ideas (not only religious ideas) and that could be interpreted by the majority as "radical" or "fanatic" positions.
It probably doesn't need to be interpreted as "radical" or even "fanatic", it actually is radical and fanatic.
I grew up in a country of 90+% Catholics, but I was raised in a minority Christian religion. Yes, we always talked about the religion, didn't party (that) much, etc. - that was because we actually cared about following our beliefs, which can't be said about Catholics in my country.
Thinking more about it led me to the following conclusion: any religion that grows so big that it becomes mainstream has to relax a lot. Religious life becomes intertwined with day-to-day problems of employment, managing the economy, etc. Meanwhile you stop having small communities that can push all unconvenient issues to outside with "us vs. them" attitude. Professional specialization starts, people are delegating their religious issues to their priests (compare the way Catholicism looks in big cities vs. small villages). And then one day you wake up and can't ignore politics anymore, because suddenly your religion is the society, and thus is the politics.
TL;DR: Going from "more fanatic / more real" to "less fanatic / less real" seems to me to be a natural course of evolution of a religion as it grows.
This is the video. It has some nice visualizations of population related statistics.
Other than water, I think the only real problem with the current and projected populations is energy. It's not cheap to get oil. And we use it in everything. So, it's really a matter of time before the question of energy makes the rest of the abundance we have useless. No cheap oil means no cheap way to ship food to markets.
So, I'm split on how to see the problem as it is. I think Malthus is going to get the last laugh on all of us.