1. How are Humans Affecting the Environment?
Human Overpopulation
Deforestation
Loss of Biodiversity
Pesticide Use
Bio Magnification
Poor Air Quality
Poor Water Quality
Loss of Natural Resources
Ozone Depletion

2. Worldwide, about half of the area covered by forests has been cleared.
Human Impact on the Environment
1. Effects of Human Overpopulation:
loss of land/habitat
water and food shortage
poor sanitation
species extinction
poverty
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

3. 6. Impact on Air Quality Global Warming Acid Rain
Atmospheric greenhouse gasses (CO2, water vapor, and methane) trap heat
= rain that has been made acidic by certain pollutants in the air
this warms planet Earth
affects climate and weather
raises sea level
affects health of ecosystems
pollutants = sulfur dioxide
and nitrogen oxides from
burning fossil fuels
causes health problems
damages forests and lakes
damages buildings

4. Brain Pop Global Warming Air Pollution (Acid Rain)
Air Pollution (Acid Rain)

5. 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

6. 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 6

7. 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

8. Depletion of 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

9. 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.

10. 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

11. Brain Pop – The Ozone Layer
O3 = Ozone