Population and Energy
Population
and Energy 1
Introduction 2
The Mortality
Revolution 4
Punctuated
Equilibrium 5
The Connection
Between Population and Economics 6
The Missing
Connection Between Population and Energy 6
An Energy
Model of Population Growth 7
Biomass Population 10
Coal Population and the Industrial Revolution 12
Oil Population and the Twentieth Century 17
Natural Gas Population and the Twenty-first Century 19
The
Sum-Of-Energies Population Model 21
Future
Scenarios 21
Scenario 1: Continued Fossil Fuel Growth 22
Scenario 2: Fossil Fuel Decline with no Sufficient
Substitute 22
Scenario 3: A New Energy Source 24
More 24
Summary 26
Bibliography 26
Figure 1: Percentage of Total Calculated Consumption Contributed by
each Energy Source 9
Figure 2:
Energy Share Dynamics 9
Figure 3:
Sum-of-Energies model of World Population 10
Figure 4: Biomass Population - World Population
800-1850 compared to Exponential growth 11
Figure 5: Coal Population – World Population less
Biomass Population 1850-1950 15
Figure 6:
World Coal Consumption 1860-2000 16
Figure 7: Oil Population – World Population less
Biomass and Coal Population 1950-2000 18
Figure 8:
World Crude Oil Consumption 1900-2000 19
Figure 9: Natural Gas Population - post-2000 20
Figure 10:
World Natural Gas Consumption 1900-2000 20
Figure 11:
World Population vs. Sum-of-Energies Population 800-2000 21
Figure 12:
Projected World Oil Production to 2050 23
Introduction
This paper will argue that populations exhibit a behaviour that could
be described as punctuated equilibrium[1].
That is, populations generally exhibit long-term homeostasis. During brief and
rare periods in history, population pressures lead to the commercialisation of
a new source of energy – particularly a higher quality energy source – which in
turn will raise the population ceiling,
or the number of people the earth can support. At this stage, populations will
grow quickly to approach the newly raised ceiling, then growth will slow and a
new homeostasis will develop.
The planet could not support the six billion
people that exist today without first the commercialisation of coal, then of
oil and gas. If these energy sources were necessary for the historically rare
and unprecedented population growth that has occurred over the last three
hundred years, then this growth might be correlated (and modelled), in some
way, after the pattern of consumption of these energy sources.
In
1750, the world’s population was approximately 720 million people. Over the
previous 1000 years, this population had been growing very slowly at an average
rate of about 0.13%. At this rate population doubles every 500 years and it
would have taken over 1500 more years (sometime near the year 3250) to reach
our current population of 6 billion people. But sometime in the 18th
century, circumstances changed and population began growing rapidly.
The
most common explanation for this change in circumstances is that a mortality revolution reduced the rate at
which people died and that this mortality revolution was brought about by the
Industrial Revolution. The Industrial Revolution changed everything. It was an
economic revolution, which spawned revolutions in science, technology,
transportation, communication and agriculture. As a consequence, humanity began
to experience improvements in health, nutrition, food variety, medicine and
quality of life. More people survived infancy and childhood and they carried on
to live longer lives. Because people were dying less quickly, populations grew
more quickly.
Large and sustained population growth is thus a contemporary
phenomenon: until historically recent times it was rare to non-existent.
Preindustrial populations grew when times were good (favourable climatic,
agricultural, political and economic conditions) and shrank when times were bad
(droughts, famines, wars, plagues, bad weather). Population growth was at all times restricted by the amount of
land and food available. Land was needed to grow food for humans, fodder for
animals and trees for building and fuel. As populations grew and occupied prime
land, people were forced onto less productive land and the competing interests
of food, fodder and fuel grew stronger.
This pressure on land led to a number of different consequences: rising
prices, under-nourishment, hunger; migration, territorial expansion through
aggression and war and internal revolt. Populations became more susceptible to
famine, disease, plague and death. Thomas Malthus referred to these
consequences as positive checks on
population growth. Population pressure also lead to what Malthus referred to as
preventive checks. Preventive checks
consisted of celibacy, reducing fertility within marriage and through increased
age at first marriage (i.e. marrying later). These observations – as
populations grew survival became more difficult (populations experienced declining marginal returns), leading to
positive or preventive checks on population growth - lead to Malthus’ famous Essay on Population (1798).
So according to Malthus, an initial population starts with few people.
It then grows in an approximately exponential manner towards demographic
saturation[2].
This exponential growth then slows as the limit to population size, or the
population ceiling, is reached. It is at
this point that populations become homeostatic. This ceiling results when
most available land has been used, and most productivity gains have been
realised. Any further expansions into less productive land, or further
productivity gains, suffer from declining marginal returns.
But events subsequent to Malthus have shown his ideas to be incomplete.
Homeostasis can be disrupted. Growth may again accelerate if a population finds
a way to shift upward its population ceiling, its demographic saturation point.
The orthodox belief is that a population ceiling shifts upward due either to
expansion into new frontiers (migration), improved productivity or
technological breakthroughs. (Example:
America’s population growth in the 19th century as frontiers
expanded.) This paper hypothesises that there may be another, more fundamental,
reason for upward shifts in a population ceiling: the commercialisation of a
new source of energy.
Ester Boserup has argued that at the stage when population pressures
are making life more miserable, food scarcer and prices higher, humans invent
technologies to overcome these pressures. “This multiplication of world
population would not have been possible without successive technological
changes.”[3]
According to Boserup, technological improvements raise the population ceiling
and allow populations to expand.
Roughly 10,000 years ago, increasing population pressure on wild food
resources led to a shift from food gathering (hunter-gatherers) to food
production (agriculturists) in several parts of the world. This lead to
demand-induced technologies and sources of energy supply, such as “water power
for flow irrigation, animal draft power, iron tools, and fire for land clearing
and for improvement of hunting and pastoralism.”[4]
Population pressures in many parts of Europe in the seventeenth and
eighteenth centuries led to serious shortages of wood which in turn lead to
many of the technological innovations that fuelled the Industrial Revolution.
Coal’s replacement of wood as the most important source of energy in Western
Europe is “a classic example of demand-induced innovation…promoted by
population pressures on forested land in Western and Central Europe.”[5]
Whereas Boserup argues that population pressures lead to technological advances, this paper argues that population pressures lead to the commercialisation of a new energy source (water and wind power, animal draft power, coal, oil and natural gas), which in turn lead to technical advances.
More recently several writers have attempted a synthesis of Malthus’
and Boserup’s ideas. Lee and Woods both show that population growth may exhibit
a series of steps: populations grow to a Malthusian ceiling, and then a change
in circumstance (be it technological advance or new energy source) raises the
ceiling and population makes a Boserupian step to the next Malthusian ceiling.
Lee and Woods have argued that in general preindustrial populations
were relatively stable, or homeostatic, over
the long-term. They grew and shrank, but over the long-term “the human population has tended toward
equilibria that have been tending upward” (Lee, 1987). A graph of preindustrial
population growth (see Figure
4) depicts this ebb and flow of population growth and
also shows the general slight long-term increase in the world’s population.
Unlike today, many parts of the world were sparsely populated. There were
frontier regions where land was sparsely populated and into which populations
could migrate when domestic situations became too crowded or life too
miserable.
The Mortality Revolution
It has been argued that there is no link between population growth and
energy use[6].
Examples are made of China (in the 1800s) and India and Africa (in the latter
half of the 1900s). These regions witnessed explosive population growth without
ever having become industrialised. Their use of coal and oil was minimal and
not a significant factor in their population growth.
Yet coal powered the trains that criss-cross India. India’s extensive
transportation network, powered by coal and later oil, becomes a great
distribution network for food. It enables populations to live in marginal
environments (like the deserts of Rahjastan). It probably explains why India
has few of the problems Africa has in feeding its population. (Has India
experienced many famines?).
In those regions, the argument goes, the greatest single factor in
population growth was mortality decline[7].
Modern medicine, health, hygiene, education, contraception are all given as
reasons for mortality decline. Energy is never mentioned.
An argument can be made that every one of those reasons were a
consequence of coal and oil use. The great Scientific Revolution was driven by
men (mostly) who were afforded the leisure to experiment and research because
machines and industry released them from the fields and provided the wealth for
an educated class.
Vaccinations (smallpox in 1796, other dates? – 1855 London sewers
modernised after cholera outbreak), developed and made in the first world,
require fuel to be distributed in the third world. Most of sub-Saharan Africa
has few oil resources yet very high population growth rates. How can there be a
correlation between energy and population? While these African countries do not
have the capital to develop vaccines, they benefit from oil purchased by the
first world that fuels the aeroplanes and trucks that distribute vaccines (and
contraceptives?) to them.
The majority of schools, hospitals and health clinics in Africa are
built with first world capital, and with first world energy. Money does not
build the schools and clinics; machines and tools, designed and built in the
developed world, produced using fossil fuels, do.
A tractor, for example, is made of metal, rubber and plastic. Plastic
is a direct by-product of oil. Metal is mined and forged using immense
quantities of heat and energy. The designer of the tractor uses a computer,
office space, lights and heating, drives to and from work in a gasoline-burning
car. The tractor is built in highly sophisticated factory that in turn must be
designed and built with metals and plastics, and required large amounts of
energy. The chain of events always has another link, but the ultimate first
cause is always inputs of energy.
Punctuated Equilibrium
This paper attempts to describe population behaviour as punctuated equilibrium: populations
generally exhibit a long-term homeostasis but during brief, unusual periods in
history certain events will dramatically raise (or lower) the population ceiling. At this stage,
populations will grow quickly to approach the newly raised ceiling, then growth
will slow substantially and a new homeostasis will develop.
In broad terms, the commercialisation of coal in the nineteenth century significantly raised the both national and global population ceilings. The commercialisation of oil in the twentieth century raised ceilings yet again. The commercialisation of natural gas may aid in squeezing ceilings up further still. And importantly, the decline of any or all of these energy sources may cause the population ceiling to return to lower levels.
Population ceilings are very difficult to determine. It is almost
impossible to say how many people the earth could have supported had there been
no commercialisation of coal and oil. It is possibly higher than 1.2 billion,
the world’s population around 1850 a date arbitrarily chosen as the start of coal population. North and South America
and Australia were all thinly populated at that time and could have sustained
much higher populations based on the use of traditional renewable energy
sources.
Similarly, without the commercialisation of oil, the world’s coal
population could also have continued to grow substantially. Some estimate that
there remain over 200 years of coal reserves[8].
Admittedly, without oil and gas, coal consumption would have been much more
rapid, but reserves and resources would likely have been large enough to
support more than the 2.5 billion people existing at the start of oil population, beginning in the middle
of the twentieth century.
Each commercialisation of a new source of energy, particularly if
higher quality than the then dominant source, raises the population ceiling.
But contrarily, each new step up the energy ladder raises productivity
per capita (assuming productivity growth can outpace population growth) and
income levels. This tends to slow population growth through several negative
effects on fertility rates.
The introduction of a new energy source affects population growth by:
- directly lowering mortality rates, through improvements in health and
safety, medicine, vaccines, etc.
- indirectly affecting fertility rates. Fertility rates are directly
affected by mortality rates, so a fall in mortality rates as described above
will likely by followed by a fall in fertility rates.
A new energy source initially precipitates a dramatic increase in
population growth due to a sharp increase in the population ceiling, then after
the effects of the new energy source are assimilated into society, growth falls
back to some steady state.
The Connection Between Population and Economics
There is a substantial literature debating the relationship between
economics and population. (Easterlin, Caldwell, etc.) Yet economics is driven
by energy. Without energy, there is no work, and without work, no economy. In
the genealogy of social forces, the top of the tree, the first cause, is always
energy.
Most analysts in seeking causes for population behaviour, be it growth,
fertility or mortality, look at socio-economic causes. Education, income,
medical facilities and employment are all suspects when population behaviour is
questioned. Yet…
The Missing Connection Between Population and Energy
Whereas the link between economics and demographics has been endlessly
debated, it is very difficult to find anything in demographic literature
relating population to energy supply or energy consumption.
In each index of three well-known books on British Population History
(Anderson, Tranter, Wrigley and Schofield) there is not one entry for ‘coal’,
‘energy’ or ‘oil’. (There is one entry on ‘coalmining communities’ in Anderson
regarding an issue not relevant to this study.) In the index of Wrigley and Schofield’s seminal 700-odd page ‘Population
History of England’ there is not one listing for either coal or energy. Yet
clearly without coal the population history of England would have been very
different
The index of Livi-Bacci’s A
Concise History of World Population contains no entries for ‘coal’ or
‘oil’. ‘Energy’ has two listings but in neither case is energy consumption or
production linked to population growth. Livi-Bacci, like so many others,
attempts to relate population growth to economic growth (ignoring energy) but
even then abandons “any attempt to determine a casual relationship between
population and economy”[9].
Vaclav Smil states, “Energy availability is … of limited usefulness in
explaining population growth…Nor is it very helpful to see the rising use of
fossil fuels, reflected in better housing, hygiene, and health care, as the key
factor driving population growth. Undoubtedly, these changes were of major
importance in Europe, but hardly so in contemporary China…Not surprisingly,
energy considerations are also of limited help in trying to explain some of the
greatest recurrent puzzles of history, the collapse of complex societies.”[10]
Yet the world’s population would not be anything like the six billion
that it is, if not for the discovery, commercialisation and mass use of coal
and subsequently oil and gas. Vast inputs of energy into modern society have
lead to vast increases in population.
An Energy Model of Population Growth
Cohen (1995) examined several different methods of curve fitting –
producing a mathematical equation describing a curve that mimics population
growth. He examined several attempts: the exponential curve, the logistic curve,
the doomsday curve and the sum-of-exponentials curve. All were found lacking
the ability to describe population growth. Curve fitting has met with little
success in describing any type of population behaviour.
But of the four models Cohen examined, the sum-of-exponentials had the
most promise. This sum-of-exponentials model divides the total population into
two or more subpopulations, fits an exponential curve to each subpopulation and
then adds the curves together to get a global picture.
His example uses two populations growing exponentially: a large but
slow growing population and a small but fast growing population. Summing these
two equations of exponential growth produces a curve whose “visual similarity
to the data on population history is not bad”[11].
Dividing the global population into subpopulations, and modelling each
of these subpopulations separately makes common sense. A population model for
Kenya will be very different from one for Sweden, or for California. Every
country, every region, has different and unique demographic characteristics.
Clearly one model cannot adequately represent such a wide variety of
circumstances. On the other hand, a regional model approach would be so complex
that any insights into the general causes of population growth would be lost.
The sum-of-exponentials model was an attempt to find a middle way.
If there is a relationship between energy consumption and population
growth, the different types of energy consumed may have different effects. If
biomass is the only energy source, populations will not grow very fast. In such
organically based economies, “the problem of expanding raw material supply, and
especially the related problems associated with the very modest energy supply
maxima…must curb growth with increasing severity as expansion takes place.”[12]
The emergence of coal as an energy source eliminated the ceiling on population
growth that any organically based culture would eventually face. Similarly, the
predominance of oil after the middle part of the twentieth century raised the
ceiling even further – it allowed even faster population growth by contributing
significantly to mortality decline through the expansion and distribution of
food, trade and vaccines and as the input to fertilisers and pesticides.
Following this hypothesis, we develop a model of population growth that
can be divided into three components: population growth due to biomass energy,
population growth due to coal and population growth due to oil. (Natural gas
will be examined briefly as its effects have only recently been felt). Each of
these components can be modelled separately and then combined together to
create a sum-of-energies model of population growth.
There is no reason to believe that all or any of these components will
exhibit exponential growth. Organically based populations may grow at a slow
exponential rate as long as there is frontier land to expand into. If frontiers
are fixed, growth may stop or redirect itself through migration. Oil based
populations may not grow exponentially at all. In fact, they may decline as
higher standards of living lower fertility – a phenomenon observed throughout
the industrialised world. Once frontiers are closed and productivity gains have
been realised, population growth may begin to plateau, exhibiting the common S
shape of the logistic curve.
The sum-of-energies model assumes that different energy sources
dominate during different periods of history. For example, traditional
renewables (wood, dung, etc.) were the world’s dominant sources of energy until
almost 1900. Coal then was the dominant source of energy until the middle of
the twentieth century, after which crude oil began to dominate. Oil remains the
dominant source of energy to this day, but its share in the energy mix peaked in
1973 and has been declining since. The natural gas share of the energy mix has
been steadily increasing and looks set to take over the number one position
sometime early this century.
Figure 1: Percentage of Total Calculated Consumption Contributed by each Energy Source
Sources: Jenkins (1989), WEC (1995), BP (2000)
Determining when the introduction of a new energy source can raise a
population’s carrying capacity to a new level is not easy and is somewhat
arbitrary. One method that seems to fit
with empirical observation is that an energy source becomes globally important
when it attains a 20% share of the world’s energy mix. For coal, this occurred
in 1860, oil in 1950, natural gas attained that level very recently.
|
|
Traditional Renewables |
Coal |
Oil |
Natural Gas |
|
20% of Energy Share |
n/a |
1860 |
1948 |
1990 |
|
Energy Share Peaks |
pre-1850 |
1912 |
1973 |
n/a |
|
20% off Peak |
1860 |
1940 |
2000 (?) |
n/a |
Figure 2: Energy Share Dynamics
Source: WEC 1995, page 10
The newly ascending energy source typically reaches 20% of the energy
mix at about the same time as the dominant source has fallen about 20% from its
peak. Figure
2 shows how coal attained 20% of the energy mix in
1860, the same time that traditional renewables had lost 20% of their original
100% share. Oil attained a 20% share in 1948, shortly after 1940 when coal had
dropped 20% from its peak of 1912.
This then will be the criterion used to separate the effects of each
energy source on the world’s population: when a new energy source attains a 20%
share of the global energy mix, it has reached a level where it can upwardly
shift the population ceiling.
The model is constructed in the following manner:
The world’s population from the beginning of time until 1850, just as
coal reached a 20% share of energy resources, will be referred to as Biomass Population. Coal Population reigns from 1850 until 1950, when oil reached a 20%
share of energy resources. Coal
Population is the population of the world not accounted for by the slowly
growing Biomass Population. That is,
it is represented by the population that remains when Biomass Population is subtracted from the world’s total population.
Similarly, Oil Population is the population from 1950 until 2000 that is not
accounted for by either Biomass
Population or Coal Population. Natural Gas Population starts
approximately now, within the last ten years, as it reaches a 20% share of
energy resources. The behaviour of Natural
Gas Population has yet to be determined. The diagram in Figure 3 illustrates these concepts.[13]
Figure
3: Sum-of-Energies model of World Population
An examination of each component follows.
Biomass Population
Until 1850, most of the world’s population was still supported by
traditional renewables (wood, dung, etc.) and
animal power (with minor amounts of wind and hydropower). Admittedly
Britain was already heavily influenced by coal, but very few other populations
were. In 1850, Britain was producing more coal than the rest of Europe
combined. In the same year, when the population of the United States was
already 23 million, 90% of its energy requirements were still met from wood[14].
So until the mid-1800s, energy from biomass was the main energy contributor to
population growth. (It still contributes to population growth. It is estimated
that 10% of the world’s energy in the year 2000 is provided by biomass and
there are an estimated two billion people that still have no access to
electricity.) Wrigley describes this
preindustrial era as the Organic Economy, and in England’s case, the Advanced
Organic Economy[15]. In this
model, it is called Biomass Population.
Biomass Population growth fluctuated in waves of feast and famine; economic growth and
population checks[16].
If populations grew too quickly, living standards declined, local carrying
capacities were exceeded and food became more expensive. Malthusian population
checks ensued: later age at first marriage, decreases in life expectancy and
higher mortality. Biomass Population had
been growing at a slow, exponential rate with some slight ups and downs for
thousands of years. In other words, it exhibited homeostatic behaviour. Population
pressures in Europe were relieved through the safety valves of migration.
Settlers expanded into sparsely populated regions of the world such as North
and South America, Australia and many African and Asian colonies. This enabled small upward shifts in the global population
ceiling, or the population equilibrium.
If Biomass
Population growth from 800 to 1850 were extrapolated to the year 2000, the
value would be 1.09 billion people. This may or may not be an indication of how
many people the planet would now be supporting if coal, oil and gas were never
commercialised, assuming there were still frontiers to expand into.
Figure 4: Biomass Population - World Population 800-1850 compared to Exponential growth
Source: McEvedy and Jones (1978)
Figure 4 shows the world’s population from 800 to
1850. The plotted line represents pre-fossil fuel population, or the world
population growth that occurred when biomass was the predominant source of
energy. The black line is a fitted line representing exponential growth.
Extrapolating the exponential trend line to the year 2000 gives a value of 1.09
billion people, as mentioned above. Hypothetically then, a world based solely
on biomass may feasibly support a magnitude of one billion people. (While it
was also just mentioned that today 2 billion people are without electricity,
they do not necessary contribute to Biomass
Population. It will be argued below that coal and oil are primary factors
in the production and distribution of food and health care that support many of
these people.)
Coal Population and the Industrial Revolution
“In ages past (pre-Industrial Revolution), better living standards had
always been followed by a rise in population that eventually consumed the
gains…Gone, Malthus’ positive checks and the stagnationist predictions of the
‘dismal science’; instead, one had an age of promise and great expectations.”[17]
Both oil and coal have been used in small quantities for thousands of
years. But until the Industrial Revolution, society’s energy requirements were
fulfilled almost entirely by human and animal power and traditional biomass
sources. For many years afterward, a large majority of the world remained
dependent on traditional biomass. By 1850 population pressures led to the
commercialisation of coal and the Industrial Revolution, and the energy derived
from coal began to shape the forces that would raise the population ceiling.
The world’s population entered a phase of disequilibrium.
In the early sixteenth century, Britain was heavily dependent on
foreign suppliers for arms. The threat of war between England and the Catholic
countries resulted in an embargo of Dutch manufactured arms to Britain. The
embargo impressed upon King Henry VIII the need for self-sufficiency in arms
manufacture so he proceeded to establish a domestic arms industry. In 1543,
according to the Elizabethan chronicler Holinshed, “the first cast pieces of
iron that ever were made in England.”[18]
Elizabeth continued the drive for self-sufficiency in many other manufactures:
for example salt, copper and glass. All of these industries were heavily
dependent on charcoal, which was made from wood. The increasing demands for
wood in concert with an increasing population lead to an alarming rise in
deforested lands first in England and then Ireland, as the search for timber
widened[19].
Although coal was dirty and smelly, the scarcity and rising costs of wood
forced many people to resort to the burning of coal for heat. Even before 1600,
“London and all other towns near the sea…are mostly driven to burn…coals, for
most of the woods are consumed.”[20]
Boserup argues that timber and charcoal became scarce, in response to population pressures
and the growing demand for these products by nascent industrial sectors. The
success of coal in the use of iron production toward the end of the eighteenth
century meant that “the shortages of energy and raw materials were overcome and
the Industrial Revolution became possible”.[21]
Since the Industrial Revolution, populations have grown much more
quickly. The countries that first experienced industrialisation were the first
to grow more quickly. England, where the Industrial Revolution began, was also
the first country to witness accelerated population growth. From the late
1700s, Britain’s population begun to grow at levels never seen before. There is
little record of population growth before approximately 1500, but lacking the
medical advances that are today taken for granted, it is unlikely historical
mortality rates could ever have been as low as ours are now. Higher historical
fertility rates were always more than compensated for by high mortality rates,
putting a brake on population growth. Since 1541, the population of Great
Britain never grew faster than it was growing by 1800.[22]
By the 1820s, England’s population was growing annually at approximately 1.6%,
a rate never surpassed before or since. (Current population growth is negative
– English population is declining for the first time since the early 1700s.)
“Between 1550 and 1820 the populations of France, Spain, Germany, Italy
and The Netherlands all appear to have grown by between 50 and 80 per cent; in
England over the same period the comparable figure was 280 per cent, a contrast
so striking that by 1820 England, which had once been a small country by the
standards of the larger European powers, though still less populous than
France, Germany or Italy, was moving rapidly towards rough equality with them”[23].
During the same period, Britain was mining coal in quantities unseen anywhere
else in the world. “In 1800 the output of coal in Britain had reached about 15
million tons a year, at a time when the combined production of the whole of
continental Europe probably did not exceed 3 million tons.”[24]
Between 1800 and 1900, the Industrial Revolution crossed the Channel
and spread to the rest of Europe. So did the importance of coal. The
commercialisation of coal that occurred in Europe in the eighteenth and
nineteenth centuries dramatically increased productivity through the use of
steam engines that drove trains, boats and many other engines, and through the
coking process used to produce steel. Coal made available twice as much heat as
an equivalent amount of dry wood.[25]
Coal is much more productive than wood – it has a higher thermodynamic
potential. By 1900, coal was powering the entire world’s major industrial
processes, and powering the industrial nations’ population growth.
Between 1800 and 1900, Europe’s population more than doubled from about
187 million to 400 million. As a percentage of world population it climbed from
21% to roughly 25%. While this percentage increase does not seem very large, it
doesn’t measure the roughly 35 million Europeans who immigrated elsewhere.
These European immigrants and their descendants spawned large and often
numerically dominant populations in many other parts of the world including the
United States, Canada, Australia, New Zealand and many regions in Latin
America. They also brought with them the European penchant for coal
consumption. By 1865 coal had gained a 20% share of energy consumption in the
United States. Shortly after 1880 coal became the main source of energy in the
U.S. As a percentage of total consumption contributed by each energy source,
coal consumption peak in 1910[26].
The year of highest population growth in the U.S. in the twentieth century
occurred in almost exactly the same year[27].
Hackett-Fischer (1996) explains population growth in the eighteen century as follows:
“There was also a modest improvement in life expectancy for infants and women during the eighteenth century, and a moderate stabilization of death-rates. But the primary cause of population growth in this period was a rise in fertility, not a fall in mortality.
Why did men and women choose to marry earlier and have more children? An improvement in material conditions was part of the answer, but not the whole of it. Husbands and wives decided to have more children because the world appeared to have become a better place in which to raise a family.”[28]
That the world appeared to have
become a better place was largely due to the commercialisation of coal and
the subsequent technological innovations.
Later, in the twentieth century, as European populations at home and
abroad began to grow more slowly, populations in other parts of the world began
to reap some of the benefits of
industrialisation. As these benefits filtered to the developing world, it too appeared to have become a better place
and developing world populations started growing more quickly. In many cases
these African, Asian and Latin American populations grew at rates never before
witnessed, eclipsing even the unusually high rates of nineteenth century
Europe. (Many started growing extremely fast after 1950 – Oil Population – due to
advanced transportation and distribution facilities ??)
Coal greatly reduced pressures of land use. Wood for heating and fuel
was replaced by coal, so the land needed to grow that wood could serve a new
purpose. The large quantities of fodder for draught animals and horse transport
were made redundant by coal and the machines driven on coal. This further
reduced pressures on land use and freed large amounts for the increased use of
agriculture for food for humans.
The commercialisation of coal eliminated the “dependence upon the
products of the land whose quantity could not be expanded indefinitely…This
ensured that the process of growth at a relatively high rate could be sustained
over a very long period. The key change that ensured the latter was the tapping
of a new store of energy capital, so abundant that its production could be
expanded immensely without causing any immediate problems of exhaustion of the
energy stock. Access to abundant energy stocks was initially of limited value
because the new sources of energy could be used only to provide heat, but once
a method had been devised for deriving mechanical work also from the new energy
source the way was clear for individual productivity to make a quantum leap.”[29]
1850 is chosen, somewhat arbitrarily, as the year that the world began
to feel the effects of coal. Around 1850
the world’s population began to grow much faster. For the first time in
history, annual world population growth exceeded 0.5%[30].
Most demographers try to explain this growth in terms of economics or mortality
decline. This model regards the phenomenon in terms of energy, in this case,
coal consumption. Obviously, coal was important in British society much
before 1850 and some continents would not feel the benefits of coal power until
much later. But by 1850 coal was being mined extensively, canal transportation
was growing quickly throughout Europe, the age of rail transport had begun and
iron-works were commonplace. This lead to increases in wealth, prices,
distribution of foodstuffs, and internal and external migration. The
substitution of machines and engines for human and animate power fostered the
improvement of material conditions and quality of life. This process began in
Britain, but the effects spread far and wide.
Figure
5: Coal Population – World
Population less Biomass Population 1850-1950
If we subtract the slowly growing Biomass Population from the total
population between 1850 and 1950, we are left with Coal Population (Figure 5). Coal
Population’s contribution to world population is then extrapolated backward
to 1750 and forward to the year 2000.
The increase in energy inputs into society from
the use of coal drove the machines that freed up time for humans to make
advances in medicine and health. Coal transported the machines that distributed
these advances through European society. Coal has a higher thermodynamic energy
potential than traditional biomass, and is able to perform more work.
Coal also played a large part in the development
of electricity. With the establishment of the electricity industry in the 1880s
following the remarkable achievements of Edison, Parsons, Stanley, Tesla,
Westinghouse and their collaborators, electricity quickly expanded to power
households, industry and railroads. Electricity was generated in power plants,
and those power plants were fed with coal. Still today, 50% of America’s power
is generated in coal-burning power plants.
These advances and productivity improvements
aided (and may have brought about) the Mortality Revolution, Urbanisation and
the Fertility Revolution (in Europe and America). During this time frontiers
were still open but were shrinking fast. (Oklahoma, the 46th state
of America, was founded in 1907).
The model predicts that Coal Population grows in a logistic manner. That is, population
initially grows quickly but eventually a coal population ceiling is reached
as coalfields diminish, coal becomes harder to extract from deeper mines, as
the productivity of machines driven by coal begins to plateau and as new,
cleaner, more productive energy sources begin to supplant coal.
Fairly reliable world coal consumption statistics are available from 1860 onwards. Current annual world coal consumption is approximately 2.2 Gtoe (giga-tonnes oil equivalent), or about 2/5 of one tonne per capita. Consumption has remained stable at this level for over a decade. Increases in coal consumption in developing countries are compensated by decreases in consumption in the developed world as these economies switch from coal to cleaner burner oil and natural gas technologies. Because coal emissions are the dirtiest of the fossil fuel emissions, pressure to reduce coal use grows with concern over the potential climate altering effects of increased carbon dioxide emissions.
Figure 6: World Coal Consumption 1860-2000
Sources: Jenkins (1989), BP (2000)
This model assumes that annual coal consumption will peak at
approximately 2.8 Gtoe. This value is midway between the World Energy Council
(WEC) future energy scenarios B and C. Scenario B is a business as usual
scenario which estimates coal use at 3.4 Gtoe in 2020 and 4.1 Gtoe in 2050.
Scenario C is an ecologically driven scenario which estimates coal use at 2.3
Gtoe in 2020 and 1.5 Gtoe in 2050. Consumption declines in scenario C after
2020 as stricter emission controls take effect.
In the case of coal, a peak of 2.8 Gtoe has no relation to the amount
of world coal reserves, which are estimated to last for over 200 years[31].
Rather future coal consumption is seen as being limited by environmental
concerns and cleaner alternatives.
If we assume that Coal Population
grows in a similar manner to coal consumption then both logistically growing
coal consumption (Figure
6) and logistically growing Coal Population (Figure
5) reach 80% of their limits in the year 2000. At this
rate Coal Population reaches a plateau of approximately 2.3 billion people in
the 21st century. In other words, at current and projected rates of coal consumption, coal supports
just under 2 billion people in the year 2000 and can be expected to support as
many as 2.3 billion people this century.
Oil Population and the Twentieth Century
Before a coal population ceiling was reached, a new source of energy
replaced coal’s dominance. Oil was the next source of energy to be
commercialised.
In 1859, Colonel E. L. Drake struck oil in Pennsylvania. More oil was
discovered in Texas in 1887. By 1900, oil was extracted in Baku on the Caspian
Sea, in Romania, California and Sumatra.
By World War I, production had expanded to Mexico, Trinidad, Venezuela
and Iran.
Population growth rates in America up until the discovery of oil in
1859 were very high, around 3%. At these rates a population doubles in size in
23 years. By 1900, the United States numbered 45 states, most of the continent
had been conquered and the high population growth rates of a country expanding
territorially in 18th century America were falling. The population
growth rate in the U.S. reached 2.11% in 1909, the highest rate ever reached in
the United States in the twentieth century.
Oil is easier to handle than coal. It is cleaner burning and cheaper to
transport and store, making it ideal as a transportation fuel. It has a higher
thermodynamic potential than coal, and was able to further increase
productivity and arguably lead to less land use demand (as oil is underground
and puts few demands on land use, whereas open face coal mines use land that
could be otherwise put to use).
It is clear that availability of fossil fuels, in
particular crude oil, as had a profound effect on population growth. Population
has grown because death rates have declined worldwide, but birth rates have
remained at high levels in many parts of the world. Oil arguably plays a part
in both phenomena.
Oil provides the energy needed to grow and
distribute food, and to increase the nutritional content of agricultural
produce. Extensive land, air and sea transportation networks enable easy
distribution of food. This stimulates mortality decline by getting food to the
people that need it, alleviating local food shortages, flying food aid to
drought stricken regions and shipping grain to countries whose populations have
grown larger than their output of food. As recently as the eighteenth century
in Europe, food was typically transported no more than 15 kilometres[32].
Today, jumbo jets transport fresh food around the world everyday.
Oil also plays a significant part in the
so-called Green Revolution that has led to growth in agricultural output that
has managed to keep up with or even exceed the number of mouths that require
feeding. Green Revolution agriculture relies on large amounts of pesticides and
fertilisers, products highly dependent on oil and gas. Intensification of
agriculture leads to surplus production, enabling greater increases in
population which in turn lead to still greater demands for food.
Water for agriculture is also highly dependent on fossil fuels. Pumping
of aquifers and groundwater for irrigation “is a phenomenon of the late
twentieth century, made possible by the availability of electricity and cheap
pumps.”[33]
Figure
7: Oil Population – World
Population less Biomass and Coal Population 1950-2000
From 1950 to 2000, Oil Population is derived by subtracting Biomass Population and Coal
Population from the world’s total population. Oil Population is plotted in Figure 7 along with a fitted logistic curve. The graph shows that currently almost 3
billion people are supported by oil.
Figure
8: World Crude Oil Consumption 1900-2000
Sources: Jenkins (1989), BP (2000)
Figure 8 plots world crude oil consumption from 1900 to 2000.
The dips in the oil consumption curve reflect the two oil shocks in the 1970s
(1973 and 1979) and the consequences of the Gulf War in 1991. There was also a
slowing of oil consumption growth in the late 1990s as a result of the economic
slowdown in Asia but presently consumption growth is increasing again as Asia’s
economy is recovering and a strong economy in America boosts demand.
A logistic curve is fitted to the oil consumption
line which assumes a peak annual consumption of 3.8 Gigatonnes of oil (Gto).
This is consistent with the WEC projected consumption in 2020 under their
scenario B – business as usual. It is substantially higher than the decline to
3.0 Gto projected in their ecologically driven scenario C but lower than the
average increase to 4.5 Gto projected in their high growth scenario A. Based on this assumed peak of 3.8 Gto per
year, the world has reached 95% of that level in the year 2000.
Assuming a similar logistic curve could represent
Oil Population as depicted in Figure 7, then Oil Population has reached 89% of its hypothetical ceiling of 3.2 billion people in the
year 2000.
There is vociferous debate as to whether growth
in oil reserves with continue to grow faster than growth in oil consumption,
allowing the ceiling of oil consumption to move upward. Alternative future
scenarios will be examined in a following section.
Natural Gas Population and the Twenty-first Century
Although the history of natural gas consumption is short and trends are
very recent, based on the above figures Natural
Gas Population may raise the population ceiling by another 500 million
people or so (Figure
9). This increase is much smaller than the increase due
either to coal or oil.
Figure 9: Natural Gas Population - post-2000
It is only speculation, but it may be that the higher the thermodynamic potential of energy sources, the less impact they have on raising population ceilings. Higher quality energy sources also lead to improvements in mortality and in standards of living. Both these factors in turn lead to lower fertility levels and thus slower, or even negative, population growth.
Figure 10:
World Natural Gas Consumption 1900-2000
The Sum-Of-Energies Population Model
This is a sum-of-energies Component view of the
world’s population:
Biomass
Population - Slow Exponential Growth - open frontiers - low
thermodynamic energy – low contribution to world’s population
Coal
Population - Fast Logistic Growth - forming frontiers -
medium thermodynamic energy – high contribution to world’s population
Oil
Population – Logistic Growth (so far) - fixed frontiers -
high thermodynamic energy – high contribution to world’s population
Natural
Gas Population - Logistic Growth (so far) - fixed frontiers -
high thermodynamic energy – low contribution to world’s population
The current best method of population projection
is the cohort-component method. But it is entirely unable to predict population
discontinuities due to famine, war, etc. It is also unable to predict baby
booms or baby busts. On a global scale, an energy-component method may be
better able.
For example, famine is very rarely due to a lack
of food, rather to a lack of food distribution. This requires energy - trains,
planes and automobiles, and fuel.
Figure
11: World Population vs. Sum-of-Energies Population 800-2000
Figure 11 shows sum-of-energies equation versus actual
population growth.
Future Scenarios
There are three general scenarios that the
world’s energy future may take. Their effects on population will be radically
different. They are:
1. Continued fossil fuel growth
2. Fossil fuel decline with no sufficient
substitute.
3. A new source of energy
Scenario 1: Continued Fossil Fuel Growth
Oil and gas resources continue to be found faster
than we consume them and population grows as projected by the UN, for example,
and for that matter almost all agencies, to between 9 and 10 billion people by
2050.
Or, based on the above sum-of-energies model, a different
interpretation might be that Oil
Population is very close to reaching a plateau of approximately 3.2 billion
people, and the world’s population may already be slowing more quickly than
most analysts realise.[34]
If so, the world’s population in 2050 may be substantially lower, closer to 7
billion people. The increased importance of natural gas in the 21st
century may raise the population ceiling, as the introduction of new energy
sources has done in the past. But based on current trends Natural Gas Population may play a smaller part in raising the
population ceiling (it may raise the ceiling by about half a billion people).
Scenario 2: Fossil Fuel Decline with no Sufficient Substitute
Oil and Gas resources are beginning to peak, as a
growing minority of experts believes.
The World Energy Council’s future energy
projections posit six future energy scenarios. Of these six, three scenarios
see oil consumption peaking at roughly current levels by 2020[35].
The International Energy Administration, in their
most recent World Energy Outlook
publication, sees oil supply peaking before 2020 and obliquely refers to an oil
supply shortfall of 19.1 million barrels per day by 2020[36].
Some industry experts (Campbell 1988 and Laherrere 1999) believe that the oil
production peak will occur much sooner.
If oil and gas production does exhibit a bell
curve shaped profile (that is production starts at zero and ends at zero, in
between production rises to a peak and then declines back toward zero) then at
some point humanity will reach the peak[37].
After that time oil and gas will become much more ‘expensive’. A decline in
production would mean a decline in energy inputs into society - less
thermodynamic energy - a decline in productivity and, hypothetically, a decline
in population. If population growth were in any way related to oil production, Oil Population may decline more quickly
than most people anticipate.
Mortality rates may increase, as a population grown large through
dependence on high quality energy sources now must allocate scarcer resources
per person. This is evident in agriculture’s dependence on fossil fuel based
fertilisers[38]. Without
them, agricultural productivity decreases and less people can be feed. Less fuel - more famines. Human carrying
capacity decreases and the ceiling on population size lowers.
Figure 12: Projected World Oil Production to 2050
Source: Campbell, The Coming Oil Crisis
Figure
12 depicts projected world oil production to 2050, based
on figures compiled by Colin Campbell in The
Coming Oil Crises. These figures are based on conventional crude oil
resources. They do not include natural gas liquids, shale oil, oil from tar
sands, ultra-deep water oil or polar oil. These oil sources are not included
because they are much more expensive
to extract, in monetary terms but also in energy terms. In other words, a large
amount of energy inputs are required to extract energy outputs from say, tar
sands in Northern Canada. Hence the net
energy gain is lower, and these energy sources may not be as important in
raising productivity and thus population ceilings.
Based on Campbell’s oil production projections, the 3.2 billion people
that are dependent on oil in the sum-of-energies population model are in
serious jeopardy in the next fifty years as the world’s remaining oil resources
are consumed, and world population could suffer a precipitous decline.
Scenario 3: A New Energy Source
This scenario follows from Ester Boserup’s observations that many of humankind’s technological innovations have resulted from population pressures, or increased population densities. According to Boserup, demand-induced innovation led to the shift from hunter-gatherer societies to agricultural societies and from the use of wood to coal. One could speculate that a shortage of fossil fuels caused by population pressures would lead to yet more innovation and the discovery of newer and better sources of energy. From our vantage point, though, it is not clear what these innovations might be nor what new sources of energy would be capable of replacing fossil fuels.
A higher quality energy source, say fission, could lead to further
productivity improvements, reducing the pressure on existing resources and
further raising the ceiling on population size. But fission still lies closer
to the realms of science fiction than science.
A lower quality energy source, like solar or wind, is less efficient.
It has lower thermodynamic potential and has less ability to perform work and
to raise productivity. For example, a recent study on
renewable energy remarks that solar radiation is completely diffuse and
contains no appreciable concentration of energy. “For this reason, the vastness
of the resource base of solar radiation is not, in itself, an indication of the
appropriateness of solar energy as a useful energy source for society.”[39]
Another problem with low quality energy sources is that
their net energy is low - they
require a large proportion of energy in, to get some energy out - in
contradistinction to oil and gas, which have high net energy values. A switch to a lower quality energy source from
fossil fuels will put further pressure on other remaining energy sources, such
as wood and coal. This could lead to further pressures on land and other
resources and hence lower the population ceiling. Low quality energy resources do not support large populations.
Nuclear power is not the answer. To replace
diminishing oil and gas (which currently provides the world with 65% of its
energy resources) with nuclear power (which currently provides 7.6%) would not
only require vast amounts of capital but would require vast amounts of high
thermodynamic energy. In a period of declining oil and gas resources, existing
energy sources would be getting scarcer.
Perhaps a new source of energy will be found with
a high thermodynamic potential. This would then add a new energy component to
population growth. This may lead to a raised population ceiling and an initial
burst of population growth as population grows to occupy the space between the
previous ceiling and the new ceiling. Then growth may slow again as a new
homeostatic situation is reached. Probably, higher productivity will have
further negative effects on both mortality (higher life expectancy/lower
mortality) and fertility.
More
As productivity growth outpaces population
growth, fertility may decline. Typically this is an economic argument. I
believe that the underlying argument is about energy, and the quality of
energy.
Agriculture, medicine, health can all be viewed
in terms of energy. In fact, even something like agriculture could be viewed as
having three components: Biomass Agriculture, Coal Agriculture and Oil and Gas
Agriculture.
Nitrogen prices have risen 25% since late
May, says Agriliance, with soaring natural gas prices taking their toll on this
essential farm input.
How much of the success of the Green
Revolution can be claimed by science, and how much by cheap fossil fuels? Cheap
fuel supplies water pumps, processing plants and field machines. It is a low
cost raw material for fertilisers, pesticides and herbicides. Agriculture is
the single largest user of fossil fuels in the U.S. (proof?).
“All the evidence suggests that we have consistently exaggerated the contributions of technological genius and underestimated the contributions of natural resources.”[40]
“Industrialisation came about at a fast enough pace so that it enlarged per capita wealth and was not entirely devoted to enlarging population. In principle, any increase in carrying capacity-temporary or permanent-affords a choice between enabling a larger number of individuals to live at previous standards. When the enlargement of carrying capacity is modest and is spread over many generations, it tends to be used mainly to increase numbers; if it is enormous and comes so suddenly that human numbers just don’t rise at the same pace, it raises living standards. The European takeover of the New World had enlarged carrying capacity (for Europeans) just fast enough to begin having this salutary effect. By drawing down stores of exhaustible resources at an ever-quickening pace, industrialization (temporarily) augmented carrying capacity even faster, affording opportunity for quite a marked rise in prosperity and for a phenomenal acceleration of population increase. The welcome rise in prosperity reinforced the dangerous myth of limitlessness and obscured for a while the hazards inherent in the population increase.”[41]
AIDS – not as a phenomenon unrelated to energy, that decreases population. But absolutely related to energy. In America where per capita energy consumption is very high, there is enough energy to fight the disease to stop its lethal effects. In Africa, they do not have the energy to fight the disease, that is the energy to develop, produce and distribute the drugs and medicines that would mitigate many of the disastrous effects. Per captia energy consumption is very low. (See Hackett-Fisher’s The Great Wave). So Africa’s potential reduction in population growth may be directly related to the world’s reduced ability to provide the necessary energy sources. In fact Africa does have substantial energy resources but the large majority of these resources are exported to the energy hungry, wealthy nations of the developed world.
Migration may be viewed in terms of energy. Populations migrate from energy poor regions to energy rich regions, either energy producers (the Middle East) or consumers (Europe, North America).
The Baby Boom
might be partially explained by the large growth in oil consumption after World
War II. (Whether the oil enabled the boom, or the boom fuelled the production
of oil doesn’t really matter. It couldn’t have happened without large energy
inputs.) It may be that populations grow quickly when first encountering a new
energy source and then slow afterwards as productivity gains permeate society
and improve education, health, etc. England’s fastest population growth ever
was in 1826 just as Wrigley’s Advanced Organic Economy was being supplanted by
his Mineral-Based Energy Economy. America’s fastest population growth after
frontiers were fixed occurred in 1909, shortly after oil discoveries first in
Pennsylvania (1859) and then Texas (1887).
Summary
It must be stressed that all of the above is merely hypothetical. Very
little account has been taking of many variables - energy intensity, energy
efficiency etc. Many figures are
hypothetical – for example, limits of coal consumption could differ widely from
the chosen value of 2.8 Gtoe.
Nuclear, hydroelectricity and renewables have not figure in this
analysis because their contributions to the global energy mix are relatively
minor. But they too must contribute somehow to population growth.
The main purpose of the paper has been to try and thrust the issue of
energy into demography’s limelight. Energy is an issue that has been widely
ignored when attempting to explain historical demography and it is widely
ignored when attempting to project future demographic scenarios. Yet I hope
this paper has shown that neither the past nor the future of demography can be
adequately explained without also examining energy’s role (not economics’!) in
the rise (and fall) of populations.
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