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.
• Food, temperature, space...
• Limiting factors – density (in)dependent - plateau
• Carrying capacity – number of inhabitants that ecosystem can sustain with
available sources.
Population growth
•Limits of growth supressed by „infinite“ amount of energy from fossil
fuels. – mechanisation of agriculture + medical advances + savage
systems + living in formerly unhabitable places.
Development of the society – maximalisation of energy flows
• „In every instance considered,
natural selection will so operate as
to increase the total mass of the
organic system, to increase the
rate of circulation of matter
through the system, and to
increase the total energy flux
through the system so long as
there is present and unutilized
residue of matter and available
energy (Alfred Lotka, 1922).
The first energy era (hunters and 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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Population growth
Source: US Census
Bureau via Wiki
The math of population growth
•Exponential growth - growth that increases at a consistent rate.
•xt=x0(1+r)t
•The rule of 70 – to find the doubling time divide the percentage
number into 70 = approximate number of years needed to double.
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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).
Demographic transition model
Source: W. Thompson
Age structure
Technological development
Ecological footprint
Source: EEA
Do we need to limit the population growth?
• 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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