population growth not exponential

 Historical growth looks exponential to me.

Maybe we're at Peak Population!

Everyone on this site that are new need to grasp the message in these films. This was the very beginning of my journey of understanding to the importance of the Exponential Function ...

~ VF ~

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 ;-)

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!

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?

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

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 ~

VF, I love the way you put things....very sober swallow.  I've read it, I grasp it.

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

When is the tipping point? 

Hi Set

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.

Hi VF

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.

The crash course should be as open to criticism now as when it was first posted. Just as scientific theories are as robust as the latest test regardless of how many tests have previously been carried out. If we stop questioning something because it has survived challenge up until now then we might as well stop thinking for ourselves altogether. Sorry but as a scientist my training pretty much forces me down this line!

I do agree that the message about human population is important and that the human footprint is huge and getting worse. Maybe I am nitpicking the detail but CM made a point in the first chapter to explain the importance of the difference between fact, opinion and belief. It is the facts that provide the edifice for the whole argument and belief construct that follows. And it is a fact that population growth is no longer exponential. You may believe this doesn't make much difference but, as I've responded to Set, you can get widely divergent results depending on it. For one thing it is not even open to question that continued exponential growth is unsustainable - as someone once said only an economist would believe such a thing! But it is very much open to opinion/belief as to whether a population leveling off at 9bn is sustainable - we won't know until or if we get there.

The belief that the facts need to be dumbed down or approximated is again a complete anathema to me as a scientist. It's not difficult to present growth extrapolations based on current rate changes and such extrapolations are not hard to grasp for anyone capable of reading a graph (see Wiki entry posted previously). Without such facts being presented accurately CM is in danger of not only misrepresenting the situation but also of losing credibility in the wider community, or at least the more scientifically minded part of it. Which would be a shame because, as I've said, I completely agree that the message about our impact on the planet and its resources is extremely important.