> The fact that the rate of growth is declining does suggest the presence of one or more constraints ...
Yes, or more likely, it's a random fluctuation indicative of nothing in particular. The latter assumption, which may seem overly skeptical, is how a scientist is expected to look at an unexplained change in the rate, based on a precept called the null hypothesis -- a presumption that (in a manner of speaking) it's all random and meaningless.
> ... and it argues against your implication that "mass death" is the only likely way out.
Not really. Remember that nature efficiently picks out those with the highest birthrates and makes them the entire future population. My point is that population growth is naturally unstable, depending only on food sources and a willingness to push other species out of the way.
1.1% per annum may not seem like a very large rate of increase, but 63 years doesn't seem like a very long time to double the world's population either.
Exponential increases of all kinds are rather scary to model. They're scary enough when one looks at compound interest and how that naturally creates a chasm between rich and poor over time, but the "big show" for exponential increases is population, where much more is at stake.
> For what it's worth, I have taken calculus.
Okay, glad to hear it. Given that, I think you will appreciate what I thought when I heard you object that population couldn't be increasing because the rate of increase was decreasing.
> And if you're the guy who wrote AppleWriter: Nice job! I liked that program. I used it in high school.
>Yes, or more likely, it's a random fluctuation indicative of nothing in particular. The latter assumption, which may seem overly skeptical, is how a scientist is expected to look at an unexplained change in the rate, based on a precept called the null hypothesis
It's NOT UNEXPLAINED and it's NOT RANDOM.
Does your browser support Flash? If I point you at a chart composed using gapminder.org could you please please LOOK AT IT? (Or if you can't, could you let me know what the constraints are on what your browser can see, so I can find another way to get you the information?) The link will follow this paragraph. Press the "play" button below this chart to see an animated plot of fertility versus child mortality. Several specific countries are hilighted - you see a trail of their progress over time - but the ENTIRE MASS of countries follows much the same pattern - it moves down and to the left. Here's the link:
It truly boggles my mind that you could think even for a second that the slowdown in population growth is "likely a random fluctuation indicative of nothing in particular". It is a TREND. The phenomenon is quite consistent. Across the ENTIRE PLANET, countries are increasing their GDP, decreasing child mortality and decreasing the rate at which they have kids, with all those changes roughly in tandem. And it's not a random walk where one needs to cherry-pick any specific interval to see these trends - if you just look at the entirety of ALL the data we have available and plot it, you can see a consistent movement.
Please look at the animation. Play around with it - use the checkbox list on the right to highlight other specific countries. Get a sense of what the data is actually DOING before you claim it's a random fluctuation.
A random walk WOULD be susceptible to cherry-picking - the trend would only show up if you pick certain time ranges or certain sets of countries.
This is not that.
(Given current trends, the world population would not double again - it would stop growing short of that.)
And that's correct -- any population increase above zero is without constraint. All one need do is calculate the doubling time:
http://arachnoid.com/lutusp/populati.html
> The fact that the rate of growth is declining does suggest the presence of one or more constraints ...
Yes, or more likely, it's a random fluctuation indicative of nothing in particular. The latter assumption, which may seem overly skeptical, is how a scientist is expected to look at an unexplained change in the rate, based on a precept called the null hypothesis -- a presumption that (in a manner of speaking) it's all random and meaningless.
> ... and it argues against your implication that "mass death" is the only likely way out.
Not really. Remember that nature efficiently picks out those with the highest birthrates and makes them the entire future population. My point is that population growth is naturally unstable, depending only on food sources and a willingness to push other species out of the way.
1.1% per annum may not seem like a very large rate of increase, but 63 years doesn't seem like a very long time to double the world's population either.
Exponential increases of all kinds are rather scary to model. They're scary enough when one looks at compound interest and how that naturally creates a chasm between rich and poor over time, but the "big show" for exponential increases is population, where much more is at stake.
> For what it's worth, I have taken calculus.
Okay, glad to hear it. Given that, I think you will appreciate what I thought when I heard you object that population couldn't be increasing because the rate of increase was decreasing.
> And if you're the guy who wrote AppleWriter: Nice job! I liked that program. I used it in high school.
Yes, that's me. Thanks.