The New Land Rush

They actually take those things into consideration, Bruce. For example, they noted rather sadly that HIV probably will not slow population growth in the countries most heavily impacted by the AIDS epidemic as much as they first thought it would.

According to the study, population growth is all about the fertility rate of adult women (duh!) In the Mid East we all know that Abdul is going to keep Abdulette barefoot and pregnant, absent some massive cultural upheavel.

[Kitsune]

Originally Posted by xoxoxoBruce

I have faith that drought, starvation and machete hacking will moderate those increases.

Harsh.

...but true.

[Undertoad]

Originally Posted by marichiko

The world population was around 2.5 billion in 1950. A world population of 9.1 billion is more than triple. I haven't noticed forests tripling or arable land tripling or the size of the earth tripling.

They need not. For example, during the same time frame, advances in farming have radically changed how food is produced, massively increasing the amount of food that can be produced in that land.

Pre-industrialization, most civilized countries required 50% of their population to be farmers in order to produce enough food. Now that number is about 1%. Things change.

Naturally this amount will increase exponentialy if the growth rate remains constant.

If you can find the person who taught you math, sue them for malpractice.

and keep the lawyers around for the people who taught you spelling and grammar

[Happy Monkey]

Originally Posted by Undertoad

If you can find the person who taught you math, sue them for malpractice.

That's more of a phrasing problem than a math problem, since it's true. "Rate" may not have been the right word, but growth is exponential.

Originally Posted by Undertoad

They need not. For example, during the same time frame, advances in farming have radically changed how food is produced, massively increasing the amount of food that can be produced in that land.

Pre-industrialization, most civilized countries required 50% of their population to be farmers in order to produce enough food. Now that number is about 1%. Things change.

Modern agriculture has not prevented famine in places like parts of Africa, India, and South America. Increasing population also means increasing degredation of the environment. Witness the pollution of the oceans, smog, the hole in the ozone layer, on and on. Technology will only take us so far, and its not nice to fool with Mother Nature.

Originally Posted by Undertoad

If you can find the person who taught you math, sue them for malpractice.

From your favorite source, Wikipedia (emphasis my own):

In mathematics, a quantity that grows exponentially (or geometrically) is one that grows at a rate proportional to its size. Such growth is said to follow an exponential law. This implies that for any exponentially growing quantity, the larger the quantity gets, the faster it grows. But it also implies that the relationship between the size of the dependent variable and its rate of growth is governed by a strict law, of the simplest kind: direct proportion. It is proved in calculus that this law requires that the quantity is given by the exponential function, if we use the correct time scale. This explains the name. An example of exponential growth is Human population, if the number of births and deaths per person per year were to remain constant

I'll send you the name of my lawyer if you wish to file a math malpractice suit of your own.

Originally Posted by Undertoad

and keep the lawyers around for the people who taught you spelling and grammar

As for spelling, Lord knows my teachers tried. I have been spelling challenged since Kindergarten.

[Undertoad]

Modern agriculture has not prevented famine in places like parts of Africa, India, and South America.

If you look at agriculture as it has been practiced in those places you will find that it is not modern. PJ O'Rourke pointed out that in Africa they had not developed the concept of the yoke, the simplest device ever invented to assist in agriculture. All we have to do is explain the yoke and their output increases by a third. I'm optimistic.

Meanwhile,

This is the Wikipedia page on exponential growth, and can you explain why it doesn't contain the last sentence of your quote?

But it does note that the general principle behind exponential growth is that the larger a number gets, the faster it grows. Any exponentially growing number will eventually grow larger than any other number which grows at only a constant rate for the same amount of time (and will also grow larger than any function which grows only subexponentially).

A steady or decreasing rate of growth is not exponential. It is subexponential.

(sigh) We're starting to split hairs, here, UT. In one of your earlier posts you implied that the population growth was supposed to stabalize in the magic year of 2050. The prediction for the population growth at that point is estimated to be .5%. If population growth were to "stabalize" at . 5%, it would still be exponential and still means a heck of a lot of new humans every year.

The page I cited does indeed include the last sentence. I will agree that human population growth is a complex issue, but I was not out of line using the word "exponential", when speaking of a population that increases at the rate of. 5% per year. I omitted the stuff that doesn't pertain to the discussion, but here you go:

Examples of exponential growth

Biology.

Microorganisms in a culture dish will grow exponentially, at first, after the first microorganism appears (but then logistically until the available food is exhausted, when growth stops).

A virus (SARS, West Nile, smallpox) of sufficient infectivity (k > 0) will spread exponentially at first, if no artificial immunization is available. Each infected person can infect multiple new people.

Human population, if the number of births and deaths per person per year were to remain constant (but also see logistic growth).

Many responses of living beings to stimuli, including human perception, are logarithmic responses, which are the inverse of exponential responses; the loudness and frequency of sound are perceived logarithmically, even with very faint stimulus, within the limits of perception. This is the reason that exponentially increasing the brightness of visual stimuli is perceived by humans as a smooth (linear) increase, rather than an exponential increase. This has survival value. Generally it is important for the organisms to respond to stimuli in a wide range of levels, from very low levels, to very high levels, while the accuracy of the estimation of differences at high levels of stimulus is much less important for survival.

Electroengineering

Charging and discharging of capacitors and changes in current in inductors are also exponential growth and decay phenomena. Engineers use a rule of five time constants to estimate when a steady state has been reached.

Computer technology

Processing power of computers. See also Moore's law and technological singularity (under exponential growth, there are no such singularities).

Internet traffic growth.

Investment. The effect of compound interest over many years has a substantial effect on savings and a person's ability to retire. See also rule of 72

Physics

Atmospheric pressure decreases exponentially with increasing height above sea level, at a rate of about 12% per 1000m.

Nuclear chain reaction (the concept behind nuclear weapons). Each uranium nucleus that undergoes fission produces multiple neutrons, each of which can be absorbed by adjacent uranium atoms, causing them to fission in turn. If the probability of neutron absorption exceeds the probability of neutron escape (a function of the shape and mass of the uranium), k > 0 and so the production rate of neutrons and induced uranium fissions increases exponentially, in an uncontrolled reaction.

Newton's law of cooling where T is temperature, t is time, and, A, D, and k > 0 are constants, is an example of exponential decay.

Multi-level marketing

Exponential increases appear in each level of a starting member's downline as each subsequent member recruits more people.

They have plows in South America. Go visit northeast Brazil sometime and see the good it does them.

[Undertoad]

Ah, ok. You took a paragraph out of the middle of the page.

You still don't understand the meaning of the word "exponential" and are fighting hard against the notion of learning it. That word "if" is the operative word in that whole sentence:

Human population, if the number of births and deaths per person per year were to remain constant (but also see logistic growth).

If. But the number of births and deaths per person per year do not remain constant.

And then there's the last bit of that sentence, the bit you left out. Where it says but also see logistic growth. If you go to that page you find that it is an example of a function where growth appears to be geometric for a while, then slows, then stops. You also learn that it is another model for population growth.

The UN's World Food Programme doesn't consider Brazil to be desperately hungry but what do they know?

Which reminds me, I have some Chilean grapes in the fridge, and it's lunchtime.

Lastly, a plow is not a yoke.

[Happy Monkey]

The problem with logistic growth is that it is exponential growth that gets modified by resource factors which push the curve back down. While in graph form that looks nice, what exactly are those resource factors? Wars? Famines? Disease? An across-the-board decision to stop having large families?

When people say that population growth is exponential, they are not saying that in the year 2500 there will be quadrillions of people on Earth - the Earth just can't support an infinite population. An exponential growth (in the colloquial sense, obviously a fixed exponent can't apply to a chaotic system) has to hit a wall at some point. The warnings about exponential growth are about what happens when we hit that wall, at which point the logistic curve kindly curves in the right direction - but why? At what cost?

[Undertoad]

Economics, modern culture, availability of birth control, availability of abortion, and secular approaches to life are probably more effective variables.

Much of Europe's birth rate has gone negative - concurrent with a general lack of wars, famines, or disease. Go figure.

[Kitsune]

Two words: Peak Oil.

Or something like that.

[Happy Monkey]

So "an across-the-board decision to stop having large families". That's the most hopeful possibility. But it has to be across the board.

[xoxoxoBruce]

You mean the stop reproducing when they run out of lubrication?

[glatt]

Originally Posted by Happy Monkey

So "an across-the-board decision to stop having large families". That's the most hopeful possibility. But it has to be across the board.

There are also pie in the sky hopes.

Maybe all of modern physics has got it wrong. After all, the grand unifying theory still hasn't been invented yet. There are holes.

[Undertoad]

Hopeful hell. Europe faces a lot of problems due to its demographic change. If the US has problems meeting medicare and social security now, imagine if the birth rate was declining.