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Putting People in the Picture: Population, Development and the Environment in the
21st Century
Source: National Geographic 2011
Global population trends Components of change
The demographic transition
Lecture learning objectives
1. Appreciate the scale and dimensions of global population growth
2. Explore the links between population, the environment and development
Population growth through history
For most of human history, global population did not exceed 10 million1804: 1 billion1927: 2 billion (123 years later)1959: 3 billion (32 years later)1974: 4 billion (15 years later)1987: 5 billion (13 years later)1998: 6 billion (11 years later)2011: 7 billion (13 years later)
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Current world population increase On 31/10/2012 the world’s population reached 7 billion It is currently growing at around 2.5 people per second78 million people per year
During this lecture 15,206 babies will be born and 6,335 people will die. The global population will increase by
8,871.
Time interval
Births Deaths Natural increase
Year 133,201,704
55,490,538 77,711,166
Day 364,936 152,029 212,907
Hour 15,206 6,335 8,871
Second 4.2 1.8 2.5
How many people were alive when you were born?
http://www.ined.fr/en/everything_about_population/world_population_me/
Continuing but slowing growth
• Nearly all growth - 97 of every 100 people - is occurring in LDCs
Demographic Components of Change
Pt+n = Pt + (B – D) {+ (I – O)}Where
Pt+n is population at time t plus n yearsPt is population at time t B is births occurring between t and t+nD is deaths occurring between t and t+n
I represents gains from immigrationO represents losses through emigration
WO
RLD
MD
Cs
LD
Cs
0
20,000
40,000
60,000
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100,000
120,000
140,000
160,000
1950
-195
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1960
-196
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1970
-197
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-198
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-199
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-200
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-201
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-202
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-203
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-204
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Vita
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nts
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0s)
Natural Increase
Births
Deaths
02,0004,0006,0008,000
10,00012,00014,00016,00018,00020,000
1950
-195
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-196
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-197
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-198
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-195
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-196
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-202
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Vita
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(00
0s) Births
Deaths
• Why did global population growth explode in the 20th Century?
• Why is the rate of global population growth decreasing?
• When/if will global population stabilise?
The demographic transition model
Describes the transition from traditional societies in which birth and death rates are high but in balance, through epochs of rapid population growth, to the situation characteristic of modern, industrial societies where fertility and mortality come back into equilibrium at new low levels
•Descriptive device - empirical observations of actual countries•Explanatory theory - attempts to explain why changes occur as they do•Predictive model - allows timing of transition to be predicted
See e.g. Thompson 1927, Notestein 1945, Dyson 2012
The demographic transition model
Mortality decline Population growth Fertility decline
Urbanisation Ageing
Associated TransitionsMobility
OccupationalEducational
Political Gender equity
Transition from a young, rural, fluctuating population through a period of rapid growth towards an old, urban population that is
stable or in decline
After Dyson 2012
Testing the DTM…
– www.bit.ly/1snrk8x– www.bit.ly/1nk5t2c – www.bit.ly/1nk6ozE
Th
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Italy
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35,000
40,000Crude Birth RateCrude Death RatePopulation
Year
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/10
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(0
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20,000
30,000
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60,000
70,000
80,000Crude Birth RateCrude Death RatePopulation
Year
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/10
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(0
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Crude Birth RateCrude Death RatePopulation
Year
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/10
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Crude Birth RateCrude Death RatePopulation
Year
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/10
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Po
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(0
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The end of world population growth…
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects: The 2012 Revision. New York
20
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5,000,000
10,000,000
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25,000,000
30,000,000
35,000,000Medium variant High variantLow variant Constant variant
Po
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(0
00
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Bifurcation into Two Global Demographic Categories
Low growth countries with rapid ageing Italy 57 million 41 million (-28%) 33.3% 65+; median age 52.5 Japan 127 million 105 (-17%) 37.8% 65+; median age 52.3
High growth countries with high fertility and low proportions of older people
India 1.03 billion 1,63 billion (+58%) (13.7% 65+); Nigeria 158 illion 289 (+82%) (6.2% 65+)
0-4 10-14
20-24 30-34 40-44 50-54 60-64 70-74 80-84 90-94 100+
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195020102050
Population (000s)
Males Females
•MDCs • Population ageing
•LDCs• Youth bulge (young age
structure)• Demographic dividend
(Transitional age structure)
Mor
e D
evel
oped
Cou
ntrie
sLe
ss D
evel
oped
Cou
ntrie
s
Per cent Urban Population: More and Less Developed Regions
Key Facts Mid 2009, no. of people in urban areas
(3.42 billion) had surpassed no. of people in rural areas (3.4.1 billion)
By 2050 this will rise to 6.29 billion – absorbing the entire world’s population growth of 2.32 billion people
Source: World Urbanisation Prospects 2009
Key Facts MDCs (74.9%)
are more urbanised than LDCs (44.6%)
Both will become more urbanised by 2050
By 2050 LDCs will account for 82.5% of the world’s urban population, up from 73.0% in 2009, and 41.5% in 1950.
Can the environment support an
increase in global living standards with a growing
population?
Population, development and the environment
Since 1990:- Population has grown by a factor 1.4 (5.3 billion to
7.2)- Life expectancy has increased from 64.8 to 70.0
years- Number of people undernourished has declined from
1 billion (18.6%) to 868 million (12.5%)
- Global forest cover has declined from 4.2-4.0 million hectares
- Carbon emissions have increased from 21,523 to 32,578 million metric tonnes (factor 1.5)
- Wild vertebrate species have fallen by more that one- third (31%) since the 1970s (GBO-3)
BUT
Is population growth: Good for the environment Bad for the environment Has no impact on the environment
Is population growth: The most important factor contributing to
environmental degradation One of a many factors contributing to
environmental degradation Not important at all
What do you think?
The Doomsters…
We are a plague on the Earth. It’s coming home to roost over the next 50 years or so. It’s not just climate change; it’s sheer space, places to grow food for this enormous horde. Either we limit our population growth or the natural world will do it for us, and the natural world is doing it for us right now
The idea that we can just keep growing forever on a finite planet is totally imbecilic…. Simon, a professor of junk mail marketing, and his kind, think technology will solve everything…. We can use up the Earth then we can just jump into spaceships and fly somewhere else…. Technology does nothing to solve problems of biodiversity or living space or arable cropland…. Fresh water and arable cropland are finite non-renewable resources…. We are already far beyond what we can support sustainably…
Dr. Paul R. Ehrlich
Sir David Attenborough
Malthus: The Principle of Population
Thomas Malthus
Essay on the Principle of Population as it affects the future improvement of society; with remarks on the speculations of
Mr Godwin, M Condercet, and other writers (1798)
Exp
on
en
tial G
row
th •Humans are impelled to increase and if unchecked, the population will grow exponentially (2,4,8,16)•The resource base to support the population grows arithmetically (1,2,3,4)
• In the natural order population growth will outstrip the food supply and the lack of food will ultimately put a stop to the increase of people
Malthusian Checks
• Positive checks – Increase the death rate– hunger, disease, warfare
• Preventative checks– Lower the birth rate– Control fertility through sexual restraint outside
and within marriage (not contraceptives)
• Ultimate consequence of population growth is poverty and misery
Easter Island
Once covered by palm forests but treeless at time of European arrival Settled 500 BC - subsistence needs easily met - carving and moving statues Forest reduction from 900 AD and palm forest gone by 1400. Statues carved 1100 and 1500….transported using trees as rollers. Loss of forest reduced water retention and led to soil erosion Population declined from 10,000 in 1500 to 2,000 at time of European
discovery in 1722. Population growth degraded the environment to the point of collapse Exacerbated by introduction of European disease, sheep and eucalypts
[Brander and Taylor (1998) The Simple Economics of Easter Island. A Ricardo/Malthus Model of Renewable Resource Use. The American Economic Review, Vol . 88, No.1, pp. 119-138.]
The BoomstersAdding more people causes problems, but people are also the means to solve these problems. The main fuel to speed our progress is our stock of knowledge, and the brake is our lack of imagination. The ultimate resource is people – skilled, spirited, and hopeful people who will exert their wills and imaginations for their own benefit, and inevitably they will benefit not only themselves but the rest of us as well. The Ultimate Resource, 1981, 1996, Princeton UP Dr Julian Simon (1932-1998)
[Population] is not a great concern in most of the world right now... Yes, an extra person is an extra mouth to feed, but it's also two hands and a brain to work and to think, and it typically works out pretty even on those areas. Second ... we peaked in [terms of] percentage increase in the early 1960s; we peaked in absolute addition to the world in the early 1990s; and what we're seeing now in most developed-world [countries] is actually a decline in populations
Dr Bjorn Lomborg
The Skeptical Environmentalist, 2001, Cambridge UP
Ester Boserup(1910-1999)
The Conditions of Agricultural Growth: The Economics of
Agrarian Change Under Population Pressure
•Argued that population growth is the major cause of agricultural change and that the principal mechanism of change is the intensification of land use through an increase in the frequency of cropping
Population growth is a stimulant...
• Boserup (cont.)– Success of the Green
Revolution in Asia was (in part) a function of the high population densities
– Africa?
• Julian Simon• The Ultimate Resource• Population growth is almost
always beneficial for economic growth
Machakos, Kenya
Relatively dry and hilly area which experienced severe deforestation and soil erosion in the early colonial period from 1900
By 1930 concerned to be an environmental disaster with an impoverished population of small farmers/pastoralists
Population increased from 240,000 (1930)to 1,393,000 (1989) (3% per annum) Introduced controls on stocking rates , forest clearance, terracing and water
management Lead to intensification of farming (shorter fallow, wider variety of crops) Improvement in transport infrastructure and links to Nairobi Migration of men – off-farm Changing gender roles
[Gould, W.T.S (2009) Population and development [electronic resource], New York : Routledge]
The ornucopians
What do geographers think?• Population dynamics affect the environment through
other variables such as culture, consumption levels, institutions, and technology
• More to population dynamics than population size and growth e.g. composition, household demographics
• Increasingly concerned with the impacts of the environment on populations!
Next: What do the numbers say?
