3-3: Human Population and the Environment

  After this lecture you should be able to…   Explain why human population growth is a central

concept in understanding environmental problems.

  Identify factors that influence human population growth.

  Analyze and describe the impacts of the demographics of a population on its environment.

  Explain factors that determine the difference in human population growth patterns based on standard of living.

Population  Dynamics  

  Popula'on  dynamics  is  the  general  study  of  how  popula'ons  change.  

  A  popula'on  is  a  group  of  individual  of  the  same  species,  living  in  the  same  area  and/or  that  are  interbreeding  and  sharing  gene'c  informa'on.  

  Demography  refers  to  the  sta's'cal  study  of  human  popula'on.  

  Demographers  analyze  popula'ons  based  on:  

  Abundance  

  Birth  Rate    

  Death  Rate  

  Growth  Rate  

  Age  Structure    Includes  Life  Expectancy/

Longevity  

Demographic  Terminology  

  Crude  Birth  Rate    Crude  Fer'lity  Rate    Total  Fer'lity  Rate    Age-­‐Specific  Birth  Rate  

  Crude  Death  Rate    Morbidity    Incidence  (per  100)    Prevalence    Cause  Specific  Death  Rate  

  Specific  Cause/10,000  

  Crude  Infant  Mortality  Rate  

  Crude  Growth  Rate    Rate  of  Natural  Increase    Doubling  Time  

  Life  Expectancy    At  Birth  Life  Expectancy    Gross  Na'onal  Product  

  Per  capita  

  NOTE:  “Crude”  numbers  are  measured  per  1000  individuals.  

  NOTE:  “Total”  number  are  measured  for  the  popula'on  as  a  whole.  

The  History  of  Human  Population  Growth  

  There  are  dis'nct  periods  of  growth/change  in  the  history  of  the  human  popula'on.    Hunter/Gather  (<  a  few  million)    Rise  of  Agriculture  

  Popula'on  density  increase  =  popula'on  growth  

  The  Plague      Decrease  in  concentrated  

popula'on  in  Europe.  

  Industrial  Revolu'on    Improvements  in  health  and  

food  supply    Today  (6.7  Billion  in  2008)  

  Growth  slowed  in  industrialized  areas,  but  same  historical  pa]erns  emerge  in  developing  regions  

Human  Population  as    Exponential  Growth  Curve  

  The  human  popula'on  (globally)  con'nues  to  grow  exponen'ally,  but  sub-­‐popula'ons  do  not  all  increase  at  the  same  rate.      

  GROWTH  RATE  EXAMPLES:    United  States=  0.6%  

  Doubling  Time  =  117  years  

  Northern  Europe  =  0.2%    Doubling  Time  =  350  years  

  Nicaragua  =  2.0%    Doubling  Time  =  26  years  

Human  Population  as    Logistic  Growth  Curve  

  Earth  provides  all  the  resources  needed  for  the  human  popula'on  to  survive.      

  The  resources  are  not  unlimited  and  resource  reduc'on  can  have  an  impact  on  popula'on  growth.  

  Data  indicates  that  while  the  human  popula'on  con'nues  to  grow  (flow),  it  is  doing  so  at  a  slower  rate  (flux).  

Inflec&on  Point  

Age  Structure  

  Popula'on  growth  curves  show  only  popula'on  size,  and  ignore  factors  that  affect  different  segments  of  the  same  popula'on.  

  Disease,  food/water  availability,  social,  economic,  and  many  other  factors  have  a  dispropor'onate  effect  on  some  age  groups  

  Age  Structure  graphs  show  the  distribu'on  of  ages  within  a  popula'on.  

Influential  Factors  on  Human  Demographic  Transition  

Resource  Limita'ons    As  resources  run  out,  

popula'ons  are  forced  to  reduce  growth  rates.  

  EXAMPLE  of  Posi've  Feedback:  increased  popula'on    increased  starva'on    increased  death  rate.  

  EXAMPLE  of  Nega've  Feedback:  Decrease  popula'on    increased  resource  availability    increased  survival.  

Improved  Technologies    As  we  have  developed  new  

technologies  we  have  increased  or  ability  to  adapt  to  certain  condi'ons.  

  EXAMPLE  of  Posi've  Feedback:  increased  popula'on    increase  disease  incidence    decrease  in  drug  availability    increase  morbidity  

  EXAMPLE  of  Nega've  Feedback:  increase  medical  treatment    decrease  disease  incidence    increase  longevity   decrease  birth  rate.  

Life  Expectancy  (Longevity)  

  Maximum  life'me  is  defined  as  the  maximum  possible  age  of  a  member  of  a  popula'on.  

  Life  expectancy  is  the  average  number  of  years  an  individual  can  expect  to  live.  

  Different  demographic  factors  play  a  role  in  determining  the  life  expectancy  of  an  individual.  

Compare  to  Average  Residence  Time!  

Population  Size  vs.  Environmental  Impact  

  To  determine  the  effect  the  size  of  a  popula'on  has  on  its  environment,  simply  mul'ple  the  size  of  the  popula'on  by  its  measureable  impact.  

  The  measureable  impact  must  include  not  only  the  ini'al  impact  of  each  individual,  but  also  the  dura'on  of  the  impact.  

  As  popula'ons  evolve,  the  resources  they  used  and  the  amount  they  use  change.  

  Addi'onally,  the  results  of  using  certain  resources  can  generate  new,  even  unexpected  impacts      EXAMPLE:  CFC’s  from  aerosols,  refrigerators,  and  air  condi'oners.  

T  =  P    X    I  

Human  Carrying  Capacity  

  The  human  popula'on,  while  the  most  innova've  and  adaptable  species  on  the  planet,  is  s'll  subject  to  environmental  pressures.  

  Human  carrying  capacity  will  be  ul'mately  be  determined  by    the  impact  that  the  human  popula'on  has  in  the  environment.    Short-­‐Term  Factors:  distribu'on  of  food    Intermediate-­‐Term  Factors:  environmental  altera'on,  resource  

availability,  technology  distribu'on.    Long-­‐Term  Factors:  soil  erosion,  decline  in  ground  water  supply,  

decrease  in  low  profile/high  need  supplies  (water,  land).  

End of Lecture Objectives

  Explain why human population growth is a central concept in understanding environmental problems.

  Identify factors that influence human population growth.

  Analyze and describe the impacts of the demographics of a population on its environment.

  Explain factors that determine the difference in human population growth patterns based on standard of living.