2 important points;

1. The rate of increase in population is now slowing which would not occur with true exponential growth, the rate of which is approximately constant.

2. Current population growth is being driven entirely by decreasing death rates in developing nations and not by increasing birth rates. This is important because although growth is baked into the cake it also means population can be projected to plateau around the 9bn mark.

Note – I am not here making a judgement on the carrying capacity of the planet or whether, if it is ever reached, 9bn will exceed it. I am merely trying to make sure the factual information wrt population is presented correctly – ascribing current population growth as exponential is incorrect and misleading wrt exrapolations based on that assertion.

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Historical growth looks exponential to me.

]]>*~ VF ~*

Do you feel I’ve failed to grasp the message or failed to appreciate the exponential function?

You might want to go back and read what I actually posted ðŸ˜‰

MarkM –

yes historically population growth does look exponential. Largely because for much of the timeline you’ve shown it was exponential. What I said is that in recent times (last few decades) the rate of growth has slowed and can therefore no longer be described as exponential.

A key feature of exponential growth is that a small growth rate can quickly give rise to a massive change in numbers. But it’s equally true that a small but continuous change in that rate can give a correspondingly large change in eventual outcome. The first part of a Hubbert curve looks exponential (I know it’s not in case anyone feels like jumping on that point) but as the rate of change reduces the curve undergoes inflexion and soon peaks out. Whether population peaks, continues to grow or plateaus is of course an open question.

It never ceases to amaze me how quick people are, here and elsewhere, to assume an agenda behind what is said rather than responding to what has actually been said!

]]>1. The rate of increase in population is now slowing which would not occur with true exponential growth, the rate of which is approximately constant.

2. Current population growth is being driven entirely by decreasing death rates in developing nations and not by increasing birth rates. This is important because although growth is baked into the cake it also means population can be projected to plateau around the 9bn mark.

[/quote]

Would you please provide a source for the first point? Also, with regards to your second point (which seems to contradict the first one) what difference does it make that “Current population growth is being driven entirely by decreasing death rates in developing nations and not by increasing birth rates” if the net result is a population increase?

]]>Maybe we’re at Peak Population!

[/quote]

INDEED…… pretty close. IF you look at the chart posted, you will see the curve going off the vertical trajectory, BUT, population is still growing at 1.6% (?), and so it still is exponential. It stops being exponential when growth rate reaches 0%. At 1%, we still have a 70 year doubling time, at 0.5% we still have a 140 year doubling time, at 0.25% we STILL have exponential growth….. it’s just that the curve changes shape.

When 0% is reached, THEN we have Peak Population, and no exponential growth. But watch out…… at that stage, we may well have reached exponential shrinkage!!!

Mike

]]>Hi VF,

Do you feel I’ve failed to grasp the message or failed to appreciate the exponential function?

You might want to go back and read what I actually posted ðŸ˜‰

[/quote]

Piquod,

I fear you’ve failed to grasp the message, but I want to genuinely find a middle ground to work with you on this. Please bear in mind that Dr Martenson has had the Crash Course completed for over a year, with all possible chances to change information within it with supporting arguement from ‘Working Joe’s’ to Mathematical Scientists, based on close to 1.5 million viewings.

Let me see if I can help with offering you World Population Estimates, that are about as precise as can be extrapolated.

1810 one Billion.

1930 two Billion.

1960 three Billion.

1975 four Billion.

1990 five Billion.

1999 six Billion.

2110 A whisker from seven Billion.

2050 Between 9.1 and 9.3 Billion.

Are we to nitpick over fripperies in explaining exponential growth in layman’s terms to a couple of generations of mathematical Luddite, or would you say that, with global oil production in the process of a decline between 4.5 and 6.7% (IEA Figures), and with human population growth figures showing that oil and population have been marching ever upward in lock step with each other since 1930, that we’ve reached a peak in human population and are about to lose a few billion to famine?

You do understand that this is the actual inferred statement?

*~ VF ~*

And yet I read you again and ouch, it’s painful. Do I have enough food?

When is the tipping point?

]]>Global population growth rates and numbers are well covered in the Wiki article;

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

Note the comments about the recent decline in rates of growth and the population curves for different regions and the whole World.

The second point appears to contradict the first only if you focus on growth rather than *exponential* growth. I don’t deny growth is still happening, what I’m saying is this can no longer be described as exponential because the rate is not constant but declining. The difference caused by the driver of growth being predominantly declining death rates comes in the extrapolation – if the trend continues then it is reasonable to extrapolate human population to a plateau as the death rate will inevitable level off. If growth were being driven primarily by birth rates at higher than required for replacement then no such plateau could be extrapolated. These outcomes diverge dramatically over periods of decades or longer and therefore have very different implications.

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