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First, I think most population growth is in "3rd world countries", so your theory of increased lifespan being the culprit doesn't really hold. The theory that

First, I think most population growth is in "3rd world countries", so your theory of increased lifespan being the culprit doesn't really hold. The theory that growth slows with economic improvements is nice, but it is not a law of nature. Besides even with no more growth, we still have billions of people who want to raise their lifestyle to Western levels, increasing their CO2 footprint by orders of magnitude. And another way to look at it: if there were only 10000 humans on earth, they would probably have a difficult time trying to move CO2 levels by a significant amount, or producing significant amounts of plastic, and so on. So clearly population size is a part of the problem.

beat 7y ago
Look at the numbers. Look at the numbers. Look at the numbers. Do not make assumptions. You're right, most high birth rate is in "third world countries"... but only some of them. Others see their birth rates drop dramatically over the course of a couple of generations, until they're at the same level as "developed" countries. And this maps almost directly to economic development. So what happens? The drop in birth rates happens concurrently with an increase in lifespans, due to eliminating disease, increasing food security, etc. This leads to an overhang of a couple of generations on old-world birthrates but new-world life expectancy - hence, population growth, even while the birth rate plummets. But give those countries a couple more generations for this hump to age out, and their population growth will level off, just like it has in older developed countries that saw their birth rates drop in the first half of the 20th century. That's just math.
- bubblewrap 7y ago
  As I said, even without growth, there are already Billions of people hungry for a more CO2 intense lifestyle. And for example birth rates dropping off could still mean more births than, say, 50 years ago, because overall there are more people. (I'm too lazy to look up the numbers, because as I said, there already are a lot of people). So if it all evens out eventually - what population size will we have reached by then? And once again - birth rates dropping off is not actually a law of nature. For how long has that effect been noticed, anyway? Industrial revolution, and good contraceptives, have not been available for very long. There may well be other phenomena emerging that counteract it. Edit: here is a chart showing that while birth rates are falling in most places, absolute number of births has been steadily increasing in the last 65 years: https://ourworldindata.org/fertility-rate#births-globally https://ourworldindata.org/fertility-rate#births-globally Absolute number of births increased 40% since 1950, from 100 Million to 140 Million per year.
  - beat 7y ago
    Population should level out around 11B, assuming no big surprises/shocks. And people aren't hungry for a more CO2 intense lifestyle - just a richer one. That's why getting off fossil fuels is so incredibly vital. Luckily, I think that moment is upon us, and we'll see fossil use die off over the next few decades. Renewables aren't just cleaner, they're cheaper now. And I don't think your chart proves your point. While the absolute number of births has increased, it has increased far less than the population as a whole (the population has tripled since 1951 - the increase in number of births is less than half the increase in number of people). Keep scrolling down the page of your link, and you see massive, massive declines in birthrates worldwide, with an extensive list of reasons why. So why would you think "there may be other phenomena emerging that counteract it"? Like what? Are you sure you aren't just clinging to a belief in population spiraling out of control that is at odds with observed facts? Because what you believe is what most people believe. And it's wrong.
    - bubblewrap 7y ago
      Your belief that everything could just be solved with renewables is incredibly naive. It's simply not proven that it can be done yet. And even renewables produce a lot of CO2. Even if they produce less than fossile fuels, the needs for 11 Billion people would be significant. A richer lifestyle means more CO2. I don't even know where you get your beliefs from, that CO2 neutral life would be easy and cheap. As for counteracting phenomena: again, it is not a law of nature that birth rates drop as people get wealthier. Even now for example there are subgroups in wealthy nations that still have high birth rates. I'm not saying it WILL happen, just that it can. And 50 years are not a very long timespan to observe to be assured about the effect of dropping birth rates.

beat 7y ago

Look at the numbers. Look at the numbers. Look at the numbers. Do not make assumptions. You're right, most high birth rate is in "third world countries"... but only some of them. Others see their birth rates drop dramatically over the course of a couple of generations, until they're at the same level as "developed" countries. And this maps almost directly to economic development. So what happens? The drop in birth rates happens concurrently with an increase in lifespans, due to eliminating disease, increasing food security, etc. This leads to an overhang of a couple of generations on old-world birthrates but new-world life expectancy - hence, population growth, even while the birth rate plummets. But give those countries a couple more generations for this hump to age out, and their population growth will level off, just like it has in older developed countries that saw their birth rates drop in the first half of the 20th century. That's just math.

bubblewrap 7y ago
As I said, even without growth, there are already Billions of people hungry for a more CO2 intense lifestyle. And for example birth rates dropping off could still mean more births than, say, 50 years ago, because overall there are more people. (I'm too lazy to look up the numbers, because as I said, there already are a lot of people). So if it all evens out eventually - what population size will we have reached by then? And once again - birth rates dropping off is not actually a law of nature. For how long has that effect been noticed, anyway? Industrial revolution, and good contraceptives, have not been available for very long. There may well be other phenomena emerging that counteract it. Edit: here is a chart showing that while birth rates are falling in most places, absolute number of births has been steadily increasing in the last 65 years: https://ourworldindata.org/fertility-rate#births-globally https://ourworldindata.org/fertility-rate#births-globally Absolute number of births increased 40% since 1950, from 100 Million to 140 Million per year.
- beat 7y ago
  Population should level out around 11B, assuming no big surprises/shocks. And people aren't hungry for a more CO2 intense lifestyle - just a richer one. That's why getting off fossil fuels is so incredibly vital. Luckily, I think that moment is upon us, and we'll see fossil use die off over the next few decades. Renewables aren't just cleaner, they're cheaper now. And I don't think your chart proves your point. While the absolute number of births has increased, it has increased far less than the population as a whole (the population has tripled since 1951 - the increase in number of births is less than half the increase in number of people). Keep scrolling down the page of your link, and you see massive, massive declines in birthrates worldwide, with an extensive list of reasons why. So why would you think "there may be other phenomena emerging that counteract it"? Like what? Are you sure you aren't just clinging to a belief in population spiraling out of control that is at odds with observed facts? Because what you believe is what most people believe. And it's wrong.
  - bubblewrap 7y ago
    Your belief that everything could just be solved with renewables is incredibly naive. It's simply not proven that it can be done yet. And even renewables produce a lot of CO2. Even if they produce less than fossile fuels, the needs for 11 Billion people would be significant. A richer lifestyle means more CO2. I don't even know where you get your beliefs from, that CO2 neutral life would be easy and cheap. As for counteracting phenomena: again, it is not a law of nature that birth rates drop as people get wealthier. Even now for example there are subgroups in wealthy nations that still have high birth rates. I'm not saying it WILL happen, just that it can. And 50 years are not a very long timespan to observe to be assured about the effect of dropping birth rates.