How are Humans Affecting the Environment?

1. Human Overpopulation

2. Deforestation

3. Loss of Biodiversity

4. Pesticide Use

5. Bio Magnification

6. Poor Air Quality

7. Poor Water Quality

8. Loss of Natural Resources

9. Ozone Depletion

• loss of land/habitat• water and food shortage• poor sanitation

1. Effects of Human Overpopulation:

Human Impact on the Environment

• species extinction• poverty• emerging disease

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

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

Global Warming Acid Rain• 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

= 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

6. Impact on Air Quality

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 agriculturalland 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

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

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

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 LayerThe 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/earthsystem/ozonelayer/

O3 = Ozone