4. The IPAT model
3 main causes or “drivers” of environmental
destruction include:
1) Population- how many people there are
2) Consumption/Production (aka “Affluence”)-
how much each person consumes
3) Technology- how efficient the production
process is that creates consumer items
I = P * A * T, or, Impact = Population x
Affluence x Technology.
5. The IPAT model
I = P * A * T, or, Impact = Population x
Affluence x Technology.
Affluence is often measured as economic growth,
or GDP per capita: GDP/population
Technology can be measured as energy intensity,
or energy used per unit of GDP growth:
energy/GDP
Implications: all factors play a role, and we
can mitigate environmental damage in 3 ways,
but focusing on only one won't suffice!.
6. IPAT: Population
Three opinions regarding the relation of population and society
can be distinguished (Homer-Dixon 1999):
1) Limits to Growth (aka Neo-Malthusians)
Believe that resource scarcities place strict limits on
population growth, and exceeding these limits may result in
social chaos.
2) No Limits to Growth (aka Economic Optimists)
Believe there are no limits to population growth because the
free market provides incentives for conservation and
technological innovation
3) Distributionists
Believe that the most significant problem is a maldistribution
of wealth and resources
7. IPAT: Affluence and Technology
Treadmill of
Production
Main idea:
Ecological
degradation is a
necessary
consequence of
societal expansion.
Ecological
Modernization
Main idea: economic
prosperity and
ecological well-
being are
compatible.
8. Thomas Malthus and
‘Over-Population’
• Contrary to popular opinion [including
your book!], Malthus did not argue
that the world would become over-
populated.
• Instead, he argued that there is a
constant equilibrium of food and
population, but that population grows
exponentially (1, 2, 4, 8, 16…),
whereas food grows only
arithmetically (1, 2, 3, 4, 5…).
• He provided no empirical evidence for
this argument.
Thomas Malthus
(1766 – 1834)
9. Thomas Malthus and
‘Over-Population’
• For Malthus, there is no such
thing as over-population! ‘Over’
what? Population cannot exceed
food supply.
• Instead, Malthus argued that
population was always already
checked, or limited, by food
production.
• For Malthus, these ‘checks’ to
population took the form of
poverty, sickness, plagues, and
even famine.
10. Thomas Malthus and
‘Over-Population’
• Summary: Malthus argues that
food scarcity poverty.
• Therefore, he argues, we cannot
(and should not) try to help the
poor.
• Helping the poor is doomed to
failure.
11. Thomas Malthus and
‘Over-Population’
• “We cannot, in the nature of
things … assist the poor, in any
way, without enabling them to
rear up to manhood a greater
number of their children”
• “the infant is, comparatively
speaking, of no value to the
society…”
12. Inequality Perspective
• Arguments
– The world doesn’t lack
food. What causes
famines is lack of access
to food. (Amartya Sen)
– No correlation between
population density (or
also cropland per capita)
and famine.
– (Japan and Netherlands
vs. most countries in
Africa, for example)
• Rebuttals
– Not all cropland is
equally productive!
– Must take into account
annual grain production
per capita, aka
environmental
productivity.
13. Demographic Transition
“Development is the best
contraceptive”?
• Stage 1: high birth rates, high
mortality rates.
• Stage 2: high birth rates, but
low mortality rates
• Stage 3: low birth rates, low
mortality rates.
14. Ecological Modernization Theory
Ecological Kuznets Curve-
economic development and
environmental degradation are
positively correlated at first, and
then negatively correlated after
a threshold of development is
reached
15. Criticisms of Ecological Modernization Theory
1. Data were cross-sectional: A snapshot at a point in time of
multiple countries does not tell us anything about the trajectory over
time of a single country.
2. EMT doesn't distinguish between an institutional reaction to a
problem, and the effect of that reaction on the problem itself, i.e.
whether it ‘modernization’ mitigates environmental degradation.
3. EMT relies on case studies that can't be generalized to other
countries, or all types of ecological degradation and pollutants (e.g.
CO2)
4. Netherlands Fallacy- the error of assuming that national
environmental impacts are contained within national borders
5. Jevons paradox: efficiency improvements don't outpace growth
16. Globalization and colonialism
• According to Bunker and Cicantell (2006), geography
colonial globalization.
• Competition among colonial powers required them
to produce at economies of scale; acquiring the
needed raw materials (with a non-random
geographical distribution), however, required
geographical expansion (or “diseconomies of space”)
