The Arithmetic of Growth and Consumption

See if you can figure out the answer to this simple mathematical brain teaser:

It relates to population increases and the idea that exponential growth can often take us by surprise. Ready?

There is one bacteria in a bottle at 11 a.m. and by noon the bottle is full of bacteria, who have been doubling their population every minute. So at 11:01 the population of the bacteria was 2, and at 11:02, it was 4, and at 11:03 it was 8, and so on. If we know the bottle will be full at noon, at what time did the bacteria realize they were going to run out of space?

The answer is 11:59 and 30 seconds or so. That’s because if the bottle is full at noon, it is HALF full at 11:59 because remember, the population doubles every minute. This is the reality of exponential growth. It’s not a linear process.

Exponential growth can take us by surprise.

So how does this story problem relate to human population growth? While the population of many developed countries is either stable or declining, the population of most developing countries such as India or China are growing exponentially. (I hesitate to even use the word “developing” for the simple reason that I don’t necessarily think that become more industrialized is a positive or “upward” development.)

Therefore, even if we in the U.S. make conscious decisions to limit our birthrate, the global population is still expected to increase 50% over what it is today by the year 2050 — to an astounding 9 billion people.

If population growth is exponential, then what time is it now, and when will we realize that we’re running out of space and resources? If you look at the example of the bacteria, you’ll realize that we can go from a borderline situation to outright disaster in a very short amount of time.

During the past 2.000 years, human population has gone from 500 million to today’s 6.5 billion. On a graph, this is a path that starts at the floor and travels upward rapidly at a 90 degree angle up the wall of time. Fortunately, since 1969 population growth is slowing overall, and although is expected to increase over the next few decades, the rate is no longer exponential. Population is expected to level off sometime after 2050.

The question is why? How and why will population rate level off? It is because people in developing countries are going to make conscious decisions to limit how many children they have? Or is it because the depletion of resources and overcrowding will cause disease and starvation?

From 1958-1961 China experienced a famine that resulted in the death of about 16-33 million Chinese. When population density is high, factors such as disease, famine, or natural disasters can have disastrous effects on the population. Thousands, if not millions, can be wiped out by a virus or food shortage.

Think for a minute what that would mean if the avian virus were to mutate and spread across Asia, then other continents. Or if a sunami or earthquake were to hit densely populated areas along the coasts...oh wait, that's already happened.

We can surmise other evolutionary and natural “checks” to a planet stressed by the population of a single species. The fertility rate in humans has dropped significantly since the turn of the 20th century. Difficulty conceiving may not just be a problematic, mysterious annoyance, but a symptom of nature’s way of population control.

The depletion of energy sources such as oil, natural gas and coal due to an ever increasing population and demand will also speed up and therefore affect population growth. When our high-energy consuming lifestyle become unaffordable, how many will have to choose between medicine and food? Heat or dinner? House or gas to get to work? There’s no need to imagine it. It’s happening right now, in the form of the mortgage crisis.

To understand the effects of growth on both population and energy source depletion, particularly oil and coal, watch Dr. Al Bartlett’s excellent presentation, “Arithmetic, Population, and Energy” at http://edison.ncssm.edu/programs/colloquia/bartlett.ram. This is an hour-long streaming video of Dr. Bartlett's famous lecture, which he has delivered variations on this lecture over 1500 times around the world. It is riveting.

He tells us the obvious – that population cannot grow unchecked and we cannot continue to drive and encourage exponential economic growth. Eventually, there will be limits to everything, and those limits can either be self-imposed or nature-imposed. We can choose to live shorter, healthier lives, have less or no children, consume much less—or—nature will do the choosing for us in the form of disease, starvation, lower fertility, climate change and ecological collapse.

Since it’s already way past 11:59 for our planet, I think I’ll have to make my own choices now that I know where things are headed.