www.ceners.org
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Population growth and energy
Filip Černoch
cernoch@mail.muni.cz
Population growth
Source: US Census
Bureau via Wiki
Population growth
• Driven by fecundity (reproductive rate) – how many offspring individual may have
in his lifetime.
• A population doesn´t grow to its full potential (indefinitelly).
• Limits of population growth – conditions for life and reproduction.
• Limiting factors
• Carrying capacity – number of inhabitants (also people) that ecosystem can
sustain with available sources.
Population growth
• Early populations grow quickly,
unimpeded by resource constraints.
• As population grows, competition for
resources grows.
• Mature population tend to reach
equilibrium and fluctuate around it.
If outgrows its carrying capacity
regulating factors (femine,
emigration) come into play.
• If a population is bellow, birth rates
tend to increase, population grows.
What factors determine carrying capacity?
• Density dependent factors
• Density independent factors
Hypothesizing the energy-population growth relationship
• Limits of growth are supressed by „infinite“ amount of energy from fossil fuels (
mechanisation of agriculture + medical advances + savage systems + living in
formerly unhabitable places).
The first energy era (hunter - gatherers)
• Human metabolism + fire.
• Muscles to secure food, shelter, aquiring material.
• Useful work of healthy adult: 50 – 90W.
• Energy returns in foraging – barely positive to as much as 40x .
• First usage of draft animals to cultivate the field (the very beginning of the
agriculture)
• Sustainable (= able to be maintained at a certain level) economy = damages were
reparable.
= If the ecosystem was harmed too much and stopped providing the resources,
people moved to another place.
The first energy transition
• Early, preindustrial agriculture (beginning between 9000 BC and 6000 BC, lasting
app. 16th century)
• Domestication of draft animals + fire to produce metals = increase of energy
usage.
• Animals: 200 – 500W.
• Fire to produce bricks and containers and to smelt metals.
• Charcoaling to convert wood to charcoal to iron (inefficient process).
• Nearly complete deforestation of some parts of Mediterranean (Spain, Cyprus,
Syria – iron) and the Near East (Iran, Afghanistan – copper).
• Considerable impact of people on the environment. Development is prevented by
the limits of the environment.
• Still no spare resources for education, science, tech development.
First prime movers
• Muscles replaced by waterwheels and windmills to grain milling, oil pressing,
wood sawing etc.
• Late 11th century England – more than 5600 water mills, 1/350 people.
• Higher performance of draft animals (better harnessing, shoeing etc.)
• Production of metals limited by the limits of environment.
• Early 18th century – typical English furnace produced app. 300 tons of pig
iron/year. 8kg of charcoal per 1kg of iron, 5kg of wood per 1kg of charcoal =
annual demand 12 000 tons of wood. All natural forests gone.
• 1 mill tons of iron requires ¼ of the British Isles under coppiced wood.
• = in 1200 London surrounding is deforested, by 1500 metal ores shipped to
Ireland, Scotland, Wales for smelting, then the the industry moves to U.S.
Industrial age
• Substitution of animate energy by engines and energies of fossil fuels (still in
process in dome areas – Africa)
• By 1900 several European countries energized by coal.
• Previously the lack of energy prevents the population from (also economic)
expansion. No spare resources for education, science, technological development.
It was changed by the fossil fuels.
• Watt´s steam machines 20kW. Industrialization, transportation, rise of well being.
An inexpensive and reliable supply of heat and electricity.
• But environmental consequences (serious changes of interactions in the
ecosystem)
• = fossil fuels provided a critical amount of energy for the humankind to develop.
They (for uncertain period of time) removes the limits of (economic and
population) expansion.
Latest energy transition
• Started by the first electricity plants in 1880s
• Electricifaciton and inovation
• An inexpensive and relable supply of electricity transformed every aspect of
everyday activities – light, time-saving gadgets, energizing transport, boosting
industrial production.
• By 1950 oil and gas approx. 35 % of the world´s primary energy supply and by
2000 their combined share over 60 %. With coal fossil fuels provides 90 % of all
commercial primary energy supply.
= fossil fuels drive up farm productivity and hence reducing (drasticaly) agricultural
population by mechanizing industrial production and letting the labor force move
into the service sector.
• But their impact on the environment is tremendous.
Development in energy consumption
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Energy-population relation
Population growth
Source: US Census
Bureau via Wiki
Demographic transition model
Source: W. Thompson
Demographic transition model
Source: W. Thompson
Age structure
Conclusions
= correlation between availability of energy and population (limiting factors
suppressed by unlimited supplies of high-quality energy).
- energy needed to provide for existing population + accommodate expected
increase.
= but fossil fuels are compromising the Earth´s ability to provide essential services
= other source of energy needed?
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Thomas Malthus (1766-1834)
• An Essay on the Principle of Population.
• Food is necessary for people to survive
• Children will continue to be born
• The power of population growth is indefinitely greater than the power of the Earth to produce
subsistence.
• Malthusian trap (population growth instead of high standard of living).
X
• Technological development.
• Relationship between afluence and population growth (demographic transition
theory).
Perspectives
• Cornucopians (boomsters, vs. Malthus and followers = doomsters)
• Reformists: Work within existing structures to make society more “green”
• Revolutionaries: Sustainability is not possible without radical change
• Environmental determinists: Ecological limits will impose changes on society
whether we like it or not
• The Voluntary Human Extinction Movement
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Technological development
Sources
Zabel, G.: Peak People: The Interrelationship between Population Growth and
Energy Resources. Energy Bulletin.
31
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