Human Impact

1
Human Impact
2
Population Growth and Environmental Impact

• Human population growth pressures physical
  environment, need for space and raw materials is
  going up

People in developed nations have a greater demand
for raw materials and generally more wasteful
than underdeveloped countries
3
Human impacts on the environment

• Global warming
• Use of machinery by humans seems to be
  increasing atmospheric CO2 levels. Carbon
  dioxide prevents heat energy from escaping,
  causes slight world wide temperature increases

Rising water temperatures causes coral bleaching
4
Human impacts on the environment

• Deforestation
• Caused by demand for wood products, need for
  space, farmland, housing, roads
• Deforestation causes habitat fragmentation
• Animals and plants are forced into confined areas

5
Human impacts on the environment

• Desertification
• Caused by over-farming
• strips the land of nutrients moisture

6
Human impacts on the environment

• Ozone depletion
• Caused by aerosol chemicals called
  chloroflurocarbons (CFCs) commonly used as
  coolants
• Escape into atmosphere, reacts with ozone (O3, a
  protective atmospheric layer)
• UV rays penetrate
  
  atmosphere and
  cause
  harm to many
  organisms

7
Human impacts on the environment

• Fishing activities
• Demand for fish and shellfish
• Fishing is harmful to the environment in many
  ways
• Bycatch, gear losses, trawling scours sea bottom

8
Human impacts on the environment

• Invasive species
• Typically introduced by people accidentally or
  intentionally
• Can cause problems if no natural enemies are
  present
• Islands and other confined ecosystems are at risk

Cane toad was introduced to Australia to control
cane beetles, pest insects that destroy sugar
cane crops Toads did not control cane beetles,
instead they took over and cane toads are
unusually hardy
9
Human impacts on the environment

• Exotic pet trade
• Capture and sell wild animals from exotic
  locations
• Wealthy buyers and collectors desire obscure
  animals
• Animals removed from
  their habitat causes an
  imbalance
  in ecosystem