Population

• Demographic dividend


  high level of economically active and a low level of young and elderly dependents
• environmental resistance 


  mortality rates controlled by environmental factors that prevent survival
• net replacement rate


  the number of children each women needs to have to maintain current population levels or zero population growth so a measure of fertility rate
• net production rate 


  a measure of the average number of daughters produced by a women in her life time
• rate of natural increase


  calculated by dividing the natural increase by 10
• replacement rate


  the number of children needed per women in order to maintain a population size which is 2.1 to account for deaths in early life
• dependency ratio


  sum that allows governments to judge how many people of working age compared to dependents they have
• Demographic transition model

  • based on demographic data from the UK
  • natural population change is affected by multiple factors influencing the total population

  A) birth rate

  B) death rate

  C) time

  D) total population

  
• weaknesses of DTM


  • developed after studying HICs so LICs may not follow same pattern
  • knowledge on disease and vaccination speeds up reduction in death rates
  • assumes linear progression
  • assumes changes are made by industrial changes and increased wealth not societal changes such as education of women
  • not applicable for high levels of development
  • doesn't account for diseases or migration
  • doesn't consider physical geography or resources
  • doesn't consider government actions
  • a 5th stage had to be added and possibly a 6th
• strengths of DTM


  • used to analyse reasons behind population change
  • shows correlation between developing economies and declining death rate
  • can predict the future of countries population so governments can plan
• importance of knowing population structure

  • amount of dependents changes amount of care homes, schools etc
  • number of economically active adjusts taxes, encourages/ discourages birth and migration, changing retirement age
  • which jobs are needed - teachers, healthcare workers
• issues with dependency ratio

  • in LICs children under 15 work on farms
  • in HICs people over 15 don't work as still in education
  • in LICs aged populations are more productive as no pensions
  • HICs will be more productive as pension age rises
  • retirement age varies
• achieving demographic dividend 


  • education
  • access to choice and family planning - contraceptives
  • quality health service
  • employment opportunites
  • smaller family size
  • higher life expectancy
• benefit of demographic dividend

  • larger work force contributes to increased labour force, economic growth and productivity
  • individuals have higher savings creating further investment
  • youthful, dynamic population brings fresh ideas and energy creating innovation and entrepreneurship
  • growing working population stimulates consumer demand and fuels domestic production
• ecological footprint 


  demand which our lives have on nature
• population ecology

  how the environment affects population factors
• population dynamics


  concept of populations changing constantly
• over population 


  if the population of an area becomes too high for the available resources the standard of living falls
• under population 


  too little people to fully utilise the environment and its resources
• optimum population 


  the ideal number of people in an area so all resources are used to give the highest economic return per person so a higher standard of living
• carrying capacity 


  the maximum population that can be supported in an environment without it being severely degraded
• global hectares (gha)


  1 gha = overall amount of resource use per hectare of productive area available
• UK is living beyond its carrying capacity but imports 46% of food and exports 60% of waste to other countries
• in the 1970s the human population overtook the rate of natural replenishment of resources so are now living unsustainable
• average world ecological footprint is 2.5 earths
• resources population model


  describes the positive and negative feedback loops between population, resources and pollution
• population resources pollution model (PRP)


  conveys the relationship between humans and the environment which is useful for planning sustainable development

  A) population

  B) pollution

  C) resource

  D) demand

  E) consumption

  F) health

  G) depleted

  
• problems with PRP model

  • ignores earths dynamic nature
  • assumes climate and food production is fixed and stable
  • doesn't consider technological advances such as green revolution
  • human population may not be able to reach a stable equilibrium
  • future number of people will impact over natural environments
  • availability of countries to use wealth counters the lack of resources
  • doesn't look at lifestyle factors of a growing population
• past unknown factor affecting population

  • contraceptives
  • green revolution
  • GM crops
  • climate change
  • medication
  • vaccinations
  • high quality of life
  • technological advancements
  • nuclear weapons
• influence on carrying capacity (I)

  I = P x A x T

  P = population

  A = affluence

  T = technology

  • where levels of affluence are technology are higher more resources are used and fewer people can be supported
  • higher technology levels means reduction of resource use and increase in carrying capacity