7 trillion humans? The Scale and impact of population growth

overpopulated_earth17 trillion looks like a typo, but no, the maths shows that either by continuing the actual global population growth levels typical the 20th century, or achieving 2% per year or far less than what is currently happening in Nigeria, the maths produce this number in a relatively short time!

A key theme of this blog is that, while population growth is no longer the threat that it once was, economic policy has yet to adapt to the slowing in population growth.  While population growth has slowed since the 20th century, growth is not at 2% as some dangerous people advocate, and all the world is not like Nigeria, it is still worth understanding just how quickly things can escalate  and not take for granted the slowing population growth that is both happening, and needed, to avert crisis.

Does it feel crowded now?  Can you imagine Earth inhabited by not 7 billion (7,000,000,000) humans, as we have now, but 7 trillion (7,000,000,000). That would be one human for every 3.3 meters x 3 meters of habitable land on the planet (calculation below).  Around 10 square meters allocation per person to live, grow food all of one food and that is without allocating any wilderness for other living things or trying to allow space (corridors?) to move outside your own space.  This is a level we would reach if were able to continue peak 20th century population growth rates.

How could we reach such levels?

Peak 20th century growth rates (1953-1990), resulted in a doubling of the population in 37 years.  Double a number 10 times, and you get 2^10 = 1,024 times the original number.  So if we had that peak growth rate from 1650 when there were estimated to be around 500 million people, we would now have 500 billion people on earth today.  Further, if we ran at those population same 20th century growth rates for 10 times 37 years from now, we would in theory reach that 7 trillion population.

Of course it is not possible to run at these population growth levels again for any length of time as world systems would literally collapse under the strain well before we reached 7 trillion.  In fact, as I have posted elsewhere, population growth has effectively collapsed since 1990.  However, there are people who declare that return to running at these growth levels or even higher, is exactly what the economy needs!

Why are such ridiculous levels advocated?

Answer: economics.  If you are a nationwide business, then you can deliver 2% growth every year if the population grows by 2% every year.  Since stock market indexes are almost exclusively such businesses, this is a formulae for the stock market to perform well. The economy to be ‘strong’. The reality is the effect is to make the rich richer, but most of the population poorer. However, big business and the very rich are great political donors and have influence, so politicians are inclined to listen. Just how significant is 2%?2% growth means 1.02 times more than last year.  1.02^35 = 2 (or 1.9999 anyway). So 2% growth produces 1,000 times more people just that little faster than our examples.

Why high birthrates would deliver no economic benefit.

I have just explained how a growing population delivers a growing customer base, which delivers growth to any business which enjoys a market share of the national market. However, that is a simplification.  Consider this graph of the population of Nigeria. This is the dream of the described ‘big business’. In five years, every age group would move up one division, and the pyramid shape ensures the result is always an increase in population for that age group as a result.  For example, the 15-19 year olds is clearly a larger group than the 20-24 year olds, so in 5 years, the number of 20-24 year olds will be a larger number. Good news if you sell to 20-24 year olds.  Now consider the graph for the USA. This time the number of 20-24 years will be quite static over 5 years.  Better for our national insurance company than Japan, where clearly customer numbers will decrease over the same period. The problem with changing the birth rates, is that in five years the only age group changed in the next five years is the 0-4 year olds.  Very little comfort for the majority of businesses that sell to adults.  Some may not realise this and still try to encourage higher birth rates, but more astute will instead try to increase immigration where ‘people prepared earlier’ are available.

 Other motivations for promoting population growth?

National pride, increased representation for religion or racial group are other reasons for people to push for population growth. “If we don’t increase our population, they will out number us!”.  Search ‘overpopulation’ myth and you discover the passionate arguments raised.  The arguments generally miss the question of where are we heading rather than were are we now, and tend to say ‘growth has been ok so far, so it must be ok forever”. The arguments focus on ‘population growth has not killed us yet’ rather than ‘have we gone past the ideal’. The arguments also generally look at the current population and miss the real issue of how much room for more population growth we have without negative consequences which may occur well before people actually starve, and what is happening to the other creatures on Earth.

Wasn’t the period of extreme growth great times?

This question misses the key point of the lag between birth rates and those newborns becoming the mainstream part of society. The graph of Japan population growth has peak corresponding to events 60 and 40 years ago. The people born during the big boom up until 1980 started being mainstream society from 1980 until now,  not during the years they were born.  If those were great years, then that may have driven high birth rates, not as a result of their being a lot of babies.

What is the ideal level?

A follow up post on this topic is coming soon.

**Land Area Calculations.

OK, these tend to be pointless, but here are some calculations anyway.  In reality it is growth rate that is important, not fixed numbers.  The fixed number could be fine, but in a time frame which from a historical perspective is very short time, all changes with the wrong growth rate.  Here is a link to someone who was so anxious to show that all is ok with an argument of convenience, he miscalculated by a factor of 1,000.  Here is another where the calculation is ok and shows dividing Texas would produce enough land for all, but like the first, assumes we need no roads, no businesses, no parks, stadiums or anything else but homes…and of course we do not need farms to produce food, nor land for the rest of the animals in the world nor rainforests or ……..but at least that last one thinks about where things are going and is confident that the population will peak within 30 years. Fingers crossed!

The land area of the earth is approximately 150 million sq kilometers. With 7 billion people, that is 0.02 sq kilometers per person. A sq kilometer,  is 1 million sq meters each, so we still have 20,000 sq meters each.  Ok, that total land is approximately 33% desert, and 25% mountains, so only 10,000 sq meters is useful, and we do have to share that with all the other living creatures and grow all our food on our allocation, but it clearly is workable.  But if we had 1,000 times more people (our allow just over 300 years of 20th century growth levels), there would be 10 sq meters usable land each to live and source all our food.  3.3 meters by 3.3 meters.

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