Is there a more pressing problem in this era of a constantly degrading global environment than the sheer number of people on the Earth? At over six and a half billion people and growing by 1.14% per year, the population will hit...

...7 billion during 2012
...8 billion during 2023
...9 billion during 2034
...10 billion during 2043

At the current rate of growth we will need 65% more energy, food, building materials, space; and all at a time when peak oil is approaching, habitats are becoming progressively fragile and the atmosphere is responding in ever more unpredictable ways to our increasing emissions. Even if growth does start to slow down, surely the planet cannot cope with these huge numbers of people. If we stop the population growing, some advocates say, then we could deal with the worst of the Earth’s damage in an easily controllable manner. But is it really that simple?

In this piece, I am going to take a different way of looking at the population problem, and try to put the impact of human numbers on the Earth into some kind of perspective.

To do any kind of analysis of the effect of population on the Earth there need to be some factors with which to work. The first one is, logically, the Absolute Population of humans, regardless of location, age, sex or any other factor. This will be called "P". Secondly, we should consider a rather difficult to pin down factor, often referred to as Standard Of Living or Material Well-Being, which is essentially the number and type of things that a human makes use of. This will be called "S". The final factor is the relative amount of resources that each of these things uses. We will call this Resource Intensity "R".

The last two factors need some explanation.

"S" is a tricky factor to quantify because everything a human uses has a cost in terms of natural resources, and these things take such a variety of forms that like for like measurement is next-to-near impossible; compare, for instance, the environmental cost of someone’s diet, to the possessions that they have. Therefore, to make things simpler, I will use "S" solely as a measure of the things each human uses that release carbon dioxide; a fair measurement, I think, of a human’s footprint on the Earth. This factor thus takes into account such things as personal transportation distance, amount of cooking, cooling, heating and lighting, and the quantity of different consumer goods purchased.

Whereas "S" is a measurement of the types of things humans use, "R" is a measurement of the - again, for the purposes of this article - amount of carbon dioxide released by each individual thing that humans use. This release can take place during the production of a thing that is used, the actual use of the thing, and that thing’s final disposal. This factor, importantly, takes into account not only the type of thing in question, but the particular way in which a thing is produced, how it functions, how it is actually used and how it is disposed of.

As we are considering carbon dioxide then the relationship between P, R and S can be expressed as a 3 dimensional space filled with CO2; with sides of length P, R and S. These 3 factors, or more accurately, variables – because they are changeable – will be "baselined" at 100 each, to give a cube of volume 1 million units of carbon dioxide. The base figure of 100 can be described as follows:

P=100, is the current population of the Earth.
S=100, is the current average "standard of living" of each human.
R=100, is the current average carbon dioxide release of each thing that makes up S.


Absolute Population ("P")

Before looking at the impact of population size on carbon dioxide, I want to talk a little bit about the nature of population change. Looking at the many things that may impact the expansion and contraction of human numbers, I can think of 5 major reasons why populations change:

1. Firstly, there are historical and related cultural reasons. This includes the way in which a nation or culture views children and family size, in a positive or negative light; the long term perception of the need for large populations, such as traditionally using children as manual farm labour; or perhaps just the fact that families in a certain area may have "always had" lots of children.
2. Religion often dictates culture, so a religion that treats children as "gifts from God" for instance, may encourage a larger population. Certainly, any religion which restricts birth control will, due to human’s instinctive need to procreate, directly lead to high population growth, providing that religion has a sufficient hold on the population.
3. Politics, in terms of educational polices, can have an even more dramatic effect, as there is a direct link between the educational level of an individual and the number of unwanted pregnancies, assuming birth control is equally available. Direct political influences, such as the policies that different governments set (and this is far more important in more dictatorial regimes), can variously lead to population growth, such as in the future army building policies of Nicolae Ceausescu, or population stabilisation or reduction, such as – at least in urban areas - the "one child" policy of China.
4. Economics has an unusual impact on population, for as population growth can reduce and even reverse as nations move from rural to urban, and from primary (production of raw materials) to secondary (manufacturing) to tertiary (service based) economies, as people become more affluent, it is not unusual in some cultures, for large families to become more popular
5. Finally, there is the often overlooked issue of group psychology, on the desire to have children. There is a natural desire for a family who have lost a child to have more children, rather than to have no more. Other forms of trauma, such as war or natural disaster, that affect the wider population, once over, also cause similar reactions; therefore we experience "baby booms" in periods of relative peace and stability. Does the reverse happen during drawn-out traumas, due to a greatly increased level of uncertainty over the future? I suspect that this may be the case.

This non-exhaustive list alone shows that controlling population merely by imposing political sanctions is not the singular answer that some population activists would have us believe.

Since 1950, the global human population has increased rapidly, but at a slowly falling rate of increase. According to the US Census Bureau, the figures are:

1950 Population = 2.56 billion
1960 Population = 3.04 billion
1970 Population = 3.71 billion
1980 Population = 4.45 billion
1990 Population = 5.28 billion
2000 Population = 6.08 billion

Now let’s add in carbon dioxide emissions, as calculated by the Carbon Dioxide Information Analysis Center in 2006:

1950 Population = 2.56 billion Emissions = 1630 million tonnes CO2
1960 Population = 3.04 billion Emissions = 2577 million tonnes CO2
1970 Population = 3.71 billion Emissions = 4076 million tonnes CO2
1980 Population = 4.45 billion Emissions = 5330 million tonnes CO2
1990 Population = 5.28 billion Emissions = 6143 million tonnes CO2
2000 Population = 6.08 billion Emissions = 6672 million tonnes CO2

This shows that as the population has increased by 237% in 50 years, the total amount of carbon dioxide emissions has increased by 409%. Even the apparent levelling off of emissions in the 1990s is not what it seems; the collapse of the Soviet Bloc caused a huge reduction in the amount of oil and coal burning by former Soviet Bloc heavy industries in the early 1990s. This trend has reversed, with the same CDIAC figures for 2001-2003 showing emissions increases of nearly 3 times the rate of population growth.

Clearly something is missing, something that is accounting for nearly 3 times as much carbon dioxide as population alone.


Standard Of Living ("S")

The most basic measures of living standards are those produced by the UN Development Programme. These measures have guided the Millennium Development Goals, which include income per capita, infant mortality, basic education and gender equality. But there is a more pernicious measure which, over the last few decades has led the so-called "consumer revolution", valuing the acquisition of material goods and leisure time activities as highly desirable, even in places where the UNDP goals are barely met.

Only six nations - USA, Germany, France, Japan, UK and Australia - accounted for 37% of the world’s carbon dioxide emissions in 2000, but a mere 10% of the world’s population. To give an example, in the USA, with emission of 5.74 tonnes of carbon per person per year, the amount of carbon dioxide emitted by motor vehicles is 515 million tonnes, almost exactly a third of the USA total . Would we consider vehicle use a basic measure of "standard of living" or an excessive use of material goods over basic need? Certainly the UNDP doesn’t consider vehicle use, beyond that which provides essential services, as a basic measure. And what of air conditioning? In the USA the carbon emissions produced by air conditioning are between 200 and 300 million tonnes per year. Most people would struggle to put air conditioning under the banner of a "basic measure".

Essentially the countries with the largest carbon emissions also have the highest per capita ownership of cars, personal computers, air conditioners, televisions, number of light fittings, and most of the other things we consider part of our modern, desirable, society; hardly any of which the UNDP consider essential to having a basic standard of living. China has overtaken the USA in absolute numbers of televisions and refrigerators, but with a population 4 times higher, the per capita use is still well below that of the USA for these, pretty representative, items. China’s total carbon emissions have just exceeded (as of 2006) those of the USA.

Now let’s put this into the carbon volume equation. Importantly, for "S", we are not measuring the amount of carbon each thing emits, just the number of each that is utilised. So we have to make the assumption that a television in India is watched for the same period of time per day as a television in the USA; that a refrigerator or air conditioning unit in China is used for the same period of time as one in the Japan (an easy assumption for the refrigerator); a car in Argentina is driven for the same number of miles as one in Germany; and each type of item has an identical level of emissions per unit of usage.

If "P" increases by 65% in 37 years, the total volume of our carbon dioxide space will rise to 1.65 million units. With over 500 million cars in the world, as of 2002, and the USA owning a quarter of them, if the world was to equal USA levels of ownership, there would need to increase to nearly 2.8 billion cars immediately, and to 4.6 billion by 2043. If this is the sort of growth we expect to see in cars, then why should we not see a similar growth in other sources of carbon. In effect, this would mean the carbon space increasing to 15 billion units of carbon dioxide. A truly terrifying figure.


Resource Intensity ("R")

But, of course, not every thing that produces carbon dioxide produces it at the same rate. It would be fair to say that consumer items, like-for-like, are manufactured in approximately the same way, and thus release about the same amount of carbon dioxide as long as the energy to manufacture them is produced in the the same way. But even this is not the case; energy use varies wildly from nation to nation, and whilst one country, such as Australia, relies havily on coal, another, like the UK, has a far higher proportion of less-polluting gas production.

Furthermore, an item may be manufactured in the same way, but it may have to travel a variety of distances to get to its place of use. The growing number of Japanese cars used in the USA, and manufactured in the Far East have to travel far further than similar vehicles manufactured in the USA itself, and thus produce a greater amount of carbon; a powerful argument on its own for local production. The same argument applies to the disposal of an item when no longer required; transportation requires energy.

When it comes to the use of an item then we have a dizzying array of values, depending on the habits of individual humans. In the UK, about 460 billion kilometres were travelled by car and light vans in 2005. In the USA the nearest available figure (2004) was 4320 billion kilometers, a per capita amount twice that of the UK. Bearing in mind that the average carbon emissions for a vehicle in the USA is also considerably more than that of the UK (approximately 1.5 times) then this alone shows a striking difference in the Resource Intensity even between similar countries. Similar, and sometimes even more dramatic figures, can be seen with the use of such heavy consumption items as air conditioning, televisions (and their ever growing size) and electric fan ovens; all of which could be easily offset by the use of similar, less polluting means.

I’m not going to suggest for a moment that the way consumerised societies use carbon emitting items and services is far less efficient than how less consumerised societies would use them, but it is easy to see what alternative directions could be taken, for better or worse. Even an increase of a modest 50% in "R" - something that can be seen in the example of vehicle efficiency - would take the carbon space up to 22.5 billion units. We must be very, very careful how we use things.


Conclusion

So, what would happen if the population stopped growing; would this really make any difference in the long run?

Taking the two example figures from the previous sections, we would still see an increase in carbon emissions of 1350% if everywhere was to follow the example of the USA in motor vehicle usage. This may be an extreme figure or it may not, but it does demonstrate that population on its own is not the biggest problem we face.

There are things that we need to do now, such as changing the way electricity is generated, reducing the distance travelled by private and commercial vehicles, reducing the power consumption of consumer items, and changing the expectations we have of what we desire compared to what we actually need to own and use.

Stopping the population growing now could buy us a few years, but unless we change the way humans think and behave - including the assumption that what we all need is the high-consumption society that developing nations’ governments seem to aspire to - then our efforts to reduce the rate of population growth will have been wasted.