The population lag: the first reason for the contradiction.

Where is the halt?
This blog states that there has been a halt to engine of the population explosion, but the global population looks to be continuing to spiral out of control! What gives?

The lag that delays any halt.
The most obvious sign of the halt of the population engine is to consider how family sizes have dropped.  However this drop in family sizes seems to be having little impact, so what gives?

Before citing the evidence for the halt in the population explosion, it is important to understand the lag.  Consider the lag like switching off the engine of an ocean liner.  The sip will stop but it takes a long time. The best way to picture the lag is to look at actual data from a country like Japan.
japan populationThis graph is from this a Japanese government web site, and was posted 10 years ago but correctly predicted the current situation in Japan.
Note that the 0-14 age group plateau in around 1960 and show decline from 1980, but the overall population continued for another 30 years before starting to decline as has now occurred. This shows the ‘engine’ had clearly been turned off by around 1960, but overall population still continued to grow.

This example shows how studying population of younger age groups can accurately predict the future. This effectively tells us the engine setting.  As the younger group ages, the drop ripples through each age group.  The decline in birth rates is just one step, and determines the number of people in the lowest age group. The data shows how a decline in birth rates can take well over 30 years to even start to show an impact on total population.  The birth rate reflects the engine setting.  Not ship speed.

So what is happening in the rest of the world?  Part 1: Birth rates.
Birth rates are the precursor to population growth level changes, so lets look at these first, and then as what is happening in terms of population. I have taken birth rate figures from this data.  Check your own country and if the setting is below 2.2, the engine for population growth (outside immigration) is already set to ‘off’.

Data from locations from all of Europe overall shows levels below the sustain level. For example simply looking at locations and finding figures at random yields: Germany(1.43),  Italy(1.42), Spain(1.48), Sweden(1.88).

In North America, the USA is declining at 2.01, as is Canada at 1.59 and Mexico at 2.29 is marginally growing marginally naturally.  In south America, Brazil is contracting at 1.79 but whether other countries are still is open to opinion.  The birth rate data I have says they still should be growing, but I read reports of declining populations.  Emigration? Possibly, so i will leave it as the rest of Latin America still in positive natural growth.

Japan (1.40) and China (1.55) have been at low levels for some time but India (2.51) is still growing. Indonesia (2.18)is still showing marginal growth, as is Sri Lanka(2.13).

Bangladesh(2.45), Pakistan(3.3), Afghanistan(5.43), and sub Saharan Africa all have significant growth still.   A drop in birth rates in some of these locations is required before the halt of the population explosion brings population to stability or a correction.

The overall picture is the rapid change from a population explosion to close to population stability but it will take another 50 years for the full affect to overcome the lag.

So what is happening in the rest of the world? Part 2:  Population.
You would think other countries with similar birth rates to Japan would have similar population outlooks,  but there is one key difference: immigration.  Japan has unusually strict rules on immigration, whereas most other countries where birth rates declined earlier are strong targets for immigration.  Movement of people around the globe changes when and where actual declines in population actually will take place and generally so far have served to lengthen the lag in between a drop in birth rates and population levelling off or heading towards decline.

While the move from explosion is currently towards relative stability with another 30 to 50 years to absorb the lag, there are still areas of the world run away growth and they tend to be the least equipped to handle their increase.

Advertisements

One thought on “The population lag: the first reason for the contradiction.

  1. Pingback: Population: just how did the ‘engine’ switch off | observ8tions

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s