Population and Migration

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Population and Migration

• Fundamental problem of global environmental
  change
• Balance supply of resources from physical system
  with demand for these resources from human
  populations over time

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Problems population-resource dynamics

• A population tragedy of the commons
• Problem of incorporating the future

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Measuring Population

• Static characteristics
• Total
• Age distribution
• Genders
• Urban/rural
• Geographic distributions

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Measuring population

• Dynamic compare one period to another and one
  age group to another and calculate rates
• Fertility
• Mortality
• Migration
• From these rates develop models that allow for
  projection and prediction

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Malthusian theories of population

• Assumptions
• Constant "passion between the sexes"
• Finite earth
• Argument
• Left unchecked, population grows and, by
  definition, grows exponentially (passion)
• After an initial period of strong growth, output
  as a function of population (labor) exhibits
  diminishing returns

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Pre-industrial Western European Demographic Regime

• High mortality positive check
• High Fertility
• Fertility Controls preventive checks
• Celibacy
• Age at marriage
• Spacing behavior
• Contraception

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Alternatives to Malthus Boserup/Simon

• Relate technological progress to population
  growth
• Population concentration leads to higher
  likelihood of technological advance.
• Population growth ? longer hours,
• More labor-intensive techniques ? eventually
  leads to more sophisticated technology
• Synthesis argument Lee, Ronald, Malthus and
  Boserup A Dynamic Synthesis, In David Coleman
  and Roger Schofield, The State of Population
  Theory, Oxford Basil Blackwell, 1986.

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Limits to Malthusian Approach

• Explaining emergence of new demographic regimes
• How technology might explain shifts
• These considerations important, because new
  regimes have emerged

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Demographic Transition

• Characterized by a drop in marital fertility
• Achieved through "stopping" behavior, i.e.
  controlling births after having the desired
  number of children

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Demographic transition

• Theory and policy
• Presented as a development model but link to
  direct link to development not clear from
  historical example
• Nevertheless basis for current views about
  population in developing world and underlies
  policy initiatives

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Fertility Declines, Real and Projected
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Stabilization Remains a Challenge
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Demographic transition the evidence

• Shift from high to low fertility was a result of
  deliberate family limitation
• Transition occurred rapidly once it began
• To date, process has been irreversible

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Sub-Saharan African Fertility Regime

• Low age at marriage
• Polygyny men have many wives, leaving few women
  celibate
• Acceptance of pre-marital and extra-marital
  sexual relations
• Remarriage after widowhood or divorce is the norm
• These are all factors that make women susceptible
  to childbearing throughout their reproductive
  period of 15-49.

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Differences in Fertility Control in
Pre-industrial European and African Regimes

• Europe reduce "exposure"
• Africa spacing behavior

Lestaeghe, Ron (1986) On the Adaptation of
Sub-Saharan Systems of Reproduction. In The State
of Population Theory, David Coleman and Roger
Schofield (eds.), Oxford Basil Blackwell
212-239.
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Characteristics of Sub-Saharan African Social
System

• Poorly defined or poorly enforced common property
  systems
• Children reared communally (polygyny)
• Share costs in time or responsibility
• Weak conjugal bonds
• Lineage holds land
• Large families have access to larger share
• References Dasgupta Partha, The Population
  Problem Theory and Evidence Journal of Economic
  Literature, 33, 4, 1995 1879-1902 Chichilnisky,
  Graciela, North-South Trade and the Global
  Environment, The American Economic Review 84 (4)
  851-874.

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Changes in life expectancy in selected African
countries with high and low HIV prevalence 1950
- 2005
with high HIV prevalence
Zimbabwe
South Africa
Botswana
with low HIV prevalence
Madagascar
Mali
1950 1955
1955- 1960
1960- 1965
1965- 1970
1970- 1975
1975- 1980
1980- 1985
1985- 1990
1990- 1995
1995- 2000
2000- 2005
Source UN Department of Economic and Social
Affairs (2001) World Population Prospects, the
2000 Revision.
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Predicted loss in life expectancy due to HIV/AIDS
in children born in 2000
Predicted life expectancy
Loss in life expectancy due to HIV/AIDS
Botswana
Zimbabwe
South Africa
Kenya
Zambia
Côte d'Ivoire
Rwanda
Mozambique
Haiti
Cambodia
0
10
20
30
40
50
60
70
Life expectancy at birth (years)
Source U.S. Census Bureau, 2000
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Environment and Migration

• Migration constitutes a significant factor in
  population dynamics
• Economic development influences migration
  patterns
• Migration and the environment are linked in two
  important ways
• Some migrations are environmentally induced
• Dust Bowls in the US, Sahel
• Migrations create environmental problems
  crowding effects

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The theory two basic considerations

• Involuntary migrations push factors
• Migrants forced out for social or environmental
  reasons are excluded from a given society and are
  forced to leave
• Voluntary migration pull factors
• Migrants decide to move from one place to the
  other on the basis of some incentives wages,
  quality of life
• Can have combination of two processes

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Involuntary migration

• Environmental factors
• Social factors
• Political, racial or religious reasons
• Other countries often are reluctant to accept
  these populations which are then concentrated in
  relatively small areas and cause environmental
  and social problems

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Voluntary Migration

• Voluntary migrations are based on incentives to
  move
• Are made explicit in form of wage differentials
  for instance
• Migration due to wage differential constitutes
  the main explanation for migrations in economics
• Puzzle why continuing migration to big
  developing country cities with overcrowding and
  high unemployment

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Harris Todaro Model

• Explain puzzle of migration using a two sector
  model with a rural (agricultural) and an
  industrial economy
• Wages in agriculture are determined by
  agricultural production and prices
• Wages in industry, generally located in urban
  areas, are dependent upon a minimum wage

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Equilibrium conditions

• As long as the urban, industrial wages are higher
  than agricultural wages, migration from rural
  areas to urban areas will occur
• This even when there is unemployment in cities
• Not wage itself but expectation of wage

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Other causal factors

• Existing social networks that support newcomers
• Increasing returns to scale in cities
• High paying jobs
• Even if difficult to obtain, raises average wage
• Segmented labor market
• Also tend to raise average wages

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Other incentive models Owen land use model

• Two types of land use, agriculture and dwelling
• Special case of areas around urban centers
• Transformation of land from agriculture to
  dwellings depends on income streams generated by
  each
• Arrival of newcomers increases income streams
  from dwellings especially if migrants get
  subsidies

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Conclusions of Owen model and further development

• Even under normal conditions, as long as there is
  an attraction to moving into an urban area such
  as a subsidy or the hope of a job, farm land will
  be urbanized down to a critical value which can
  be very close to zero.
• Higher interest rate to obtain credit for
  agricultural investments as opposed to those for
  investment in urban dwellings will accelerate the
  process.

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Further aggravating conditions

• Foreign aid and relief can accelerate the process
• An ill-defined property right regime will
  initially slow but then accelerate the process
• Climate change might accelerate the process
• Reduce net profits made from agricultural
  production
• Floods, sea level rise, etc. reduce available
  land, other resources

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Future problems and uncertainties

• Evolution of African population patterns
• Response of regions where population below
  replacement rate
• Lower population levels
• Pro-natalist policies
• Role of migration in redistributing population
• Role of climate
• Potential for increased conflicts

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Trade and Environment

• From a general point of view, trade and the
  environment should be neutral with respect to
  each other
• Problems come from the different political social
  and legal structures between countries
• These lead to either advantageous or problematic
  relationships between the two

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Positive and negative effects

• Environmental conditions can be positively
  affected by trade liberalization
• Positive effects can result from the suppression
  of distortions which have all kinds of costs
  including environmental ones
• Other legislation than trade legislation might
  create distortions environmental standards
• A market economy, and this is true for trade as
  well, can work optimally only if some structural
  conditions are similar such as property rights
• To make all this explicit look at trade theories

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Property Rights, the Environment and Trade

• Changes in the Economic Theory of Trade
• Traditional Theory Based on the Notion of
  Comparative Advantage Heckscher Olin
• 2 New Notions
• Importance of Increasing Returns to Scale and
  Intra-Industry Trade (Helpman, Krugman, Ethier,
  etc.)
• Importance of availability of a factor and factor
  prices (Chichilnisky)

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Characteristics of Trade

• Importance of increasing returns in
• External aspects
• Monopolistic competition
• Some property rights regimes lower the price of
  factor inputs
• Countries with ill-defined property rights
  extract too many natural resources
• They have thus an "artificial" comparative
  advantage in environmental goods

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The Chichilnisky Perspective

• Chichilnisky (1994) has analyzed trade links
  between regions with different property rights
• Basic conclusions are drawn from her
  investigation
• The region with undefined property rights will
  supply more of a resource at any price
• This applies to any good that is "fugitive"
  rights of ownership established only when
  captured or freely extractable

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Open access and private supply
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Chichilnisky Perspective

• Apparent "abundance" of resources when no or
  ill-defined property rights
• Region "appears" to have a comparative advantage
  in the given resource.
• Abundance not due to any intrinsic natural
  availability of the resource but reflects absence
  of rights.
• Region without property rights gets poorer
  because it divests its resources at too low a
  price.

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Chichilnisky Analysis

• Assumptions about regions without well defined
  property rights
• Elasticity of substitution between leisure and
  consumption for harvesters or extractors of the
  resource good is lower than 1
• Extractors consume mostly other goods than the
  natural resource that are purchased with their
  harvest or catch
• An increase of the relative price of other goods
  with respect to the resource will result in more
  extraction

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Consequences

• Regions with ill-defined property rights are
  "exploited" by those with well defined rights.
• Resultant lower prices lead to increasingly
  unfavorable terms of trade followed by more
  extraction of the resource
• Thus regions with poorly defined property rights
  grow poorer as a result of trade with regions
  with better defined property rights
• More important, corrective taxes are
  counterproductive lower demand and lower prices
  lead to more extraction

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Analysis of Countries with Ill-Defined Property
Rights

• These countries are sensitive to price
  fluctuations due to substitution effects or
  taxation policies
• Lower prices lead to more extraction of natural
  resources due to a lowering of the opportunity
  cost of labor
• This lowers their bargaining power at the
  international level
• Their bargaining power is lowered further by the
  cost of the artificial "comparative advantage" in
  terms of natural resources on the society as a
  whole which might lead to social upheavals.