Transcript Human Impacts on Environment

How are Humans Affecting the
Environment?
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9.
Human Overpopulation
Deforestation
Loss of Biodiversity
Pesticide Use
Bio Magnification
Poor Air Quality
Poor Water Quality
Loss of Natural Resources
Ozone Depletion
Human Impact on the Environment
1. Effects of Human Overpopulation:
• loss of land/habitat
• species extinction
• water and food shortage
• poverty
• poor sanitation
• emerging disease
2. Deforestation – loss of forests
- cause soil erosion, loss of habitat, and species extinction
Worldwide, about half of the area covered by forests has been cleared.
3. Loss of Biodiversity – the variety of organisms in an ecosystem
- an imbalance can cause extinction
4. Pesticide Use – using chemicals to kill and control pests
- will sometimes kill non-target species
- pollutes water sources
- causes health problems
5. Biological Magnification/Bio Accumulation
– concentrations of a harmful substance increase
in organisms at higher trophic levels in a food web
6. Impact on Air Quality
Global Warming
• Atmospheric greenhouse
gasses (CO2, water vapor, and
methane) trap heat
• this warms planet Earth
• affects climate and weather
• raises sea level
• affects health of ecosystems
Acid Rain
= rain that has been made
acidic by certain pollutants in
the air
• pollutants = sulfur dioxide
and nitrogen oxides from
burning fossil fuels
• causes health problems
• damages forests and lakes
• damages buildings
Brain Pop
• Global Warming
– http://www.brainpop.com/science/earthsystem
/greenhouseeffect/
• Air Pollution (Acid Rain)
– http://www.brainpop.com/science/ourfragileen
vironment/airpollution/
7. Impact on Water Quality
The runoff of silt, soil, pesticides, and fertilizers from agricultural
land is the largest single source of water pollution.
8. Eutrophication:
- excess detergents and fertilizers can run off into lakes and ponds
- this stimulates plant and algae overgrowth
- a buildup of algae can lower the levels of dissolved oxygen in
the water
- this leads to the dying off of the fish population
Why can’t you just clean up
polluted water?
- it is expensive
- Who is to pay for it?
- Technology not available for all types
8. Impact on Natural Resources
Renewable Resources
- can regenerate if they are alive or can be replenished
by biochemical cycles if they are nonliving
- ex. trees, fresh water
Nonrenewable Resources
- cannot be replenished by natural processes
- ex. fossil fuels
Sustainability = a way of using natural resources without
depleting them for future generations
• use renewable resources that can be “restocked”
• recycle and reuse products
• plant tree farms
• only cut down selected trees instead of clear-cutting
• follow emission standards
The Story of Easter Island
• Humans first landed on Easter Island between 400 and 700 A.D.
• Island had thick forests, rich soil, many bird and animal species
• Human population grew quickly over next 1000 years
• They cut down forests for lumber and boats faster than the trees
could grow back
• Eventually, there were no trees left….no wood for shelter or boats,
rich soil washed away, habitat lost for animal species, no fishing
without boats
• With no food, and island resources nearly gone, the Easter Island
human population crashed and the Easter Islanders disappeared
Depletion of the Ozone Layer
The Ozone Layer:
• A thin layer of O3 gas
located in the
stratosphere
• Filters out (and protects
us from) harmful UVA
rays emitted by the Sun
• UVA rays cause
cataracts and skin
cancer
How is the Ozone being
depleted?
• From the use of chlorofluorocarbons (CFC’s)
• CFC’s are chemicals used in
– Aerosols
– Styrofoam
– Cooling agents in refrigerators and air
conditioners
• Kept sealed, CFC’s pose no threat to the
environment, however, once released to the
atmosphere, they break ozone molecules apart.
• Thus, the ozone hole.
What has been done to protect
the ozone layer?
• The Montreal Protocol
– Developed in 1987 by Canada
– Treaty signed by several countries to limit the
use of CFC’s
– CFC’s have now been completely phased out
– As a result, our ozone is regenerating
Brain Pop – The Ozone Layer
• http://www.brainpop.com/science/earthsys
tem/ozonelayer/
O3 =
Ozone