Human Impact on Ecosystems

1

Earth’s Human Population Continues to Grow

• Earth’s human carrying capacity is unknown

• Technology has helped to increase Earth’s carrying capacity.

– gas-powered farm equipment

– medical advancements– clean water– public assistance

2

Overpopulation• Over 6.6 billion people• Many natural resources are

nonrenewable– Fossil fuels take millions of years

to form

• More people means:– 1) More forests removed– 2) More resources consumed– 3) More CO2 released

3

4

• Nonrenewable resources are used faster than they can form or be replenished:– Coal– Oil– Natural Gas

• Renewable resources cannot be used up or can replenish themselves over time :– Wind– Solar– Water 5

Earth’s Natural Resources • The growing human population puts pressure on Earth’s

natural resources

Ecological Footprint• Defined: the amount of

land needed to support a person.

• The land must produce and maintain enough– food and water– shelter– energy– waste

• Several factors effect size:– Amount/efficiency of

resource used– Amount/toxicity of

waste produced 6

WHAT ARE SOME ENVIRONMENTAL ISSUES

CAUSED BY HUMAN ACTIVITY?

7

Ozone Layer Depletion• Ozone Function: Block

UV radiation from sun• Cause:

– CFCs (air pollution) thin the ozone layer

– More UV radiation reaches the surface

• Effects: – Crop damage– Skin cancers– Eye damage

• Solution: – Reduce/Regulate CFCs– Plant trees

UV

Ozone layerOzone layer

CFCs

UV

8

Smog and Ground-Level Ozone• Causes:

– Burning of fossil fuels & industry

• Particulates rise into air and react with sunlight to make air pollution

• Effects:– Ozone gas (O3)is poisonous– Respiratory illness

• Solutions:– Reduce use of fossil fuels– Alternative energy sources– Plant trees

9

The Greenhouse Effect• G.H.E. is naturally good (it

warms Earth)• Causes: CO2 from burning

of fossil fuels (coal, oil, natural gas)

• Effects: Excess heat trapped near the earth’s surface may change global climate patterns; ice caps melt

• Solutions: Reduce use of fossil fuels, plant trees, alternative energy sources

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What’s a Greenhouse?A Greenhouse is designed to trap heat so you can grow plants year round, even in cooler environments.

heat

heat

heat

heat

Some heat escapes the greenhouse, but enough is trapped to keep the inside warm

Earth

heat

heat

Some heat escapes into space Some heat

naturally trapped by CO2 and other greenhouse gases

The Natural Greenhouse Effect is good for life on Earth.

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2CO2

CO2

CO2

heatheat

heat

Earth

CO2, Methane, other greenhouse gases

Earth

heat heatheat

Excess CO2 in atmosphere

Less heat escapes into space

More heat trapped near Earth’s surface

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2CO2

CO2

CO2

CO2

CO2 CO2

CO2

CO2CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2CO2

CO2

heatheat

heat

The Greenhouse Effect is naturally GOOD!

Mars: No Greenhouse Effect

Little heat is trapped by the thin CO2 atmosphere. High temperatures can be around 20⁰F.

Earth: Balanced Greenhouse Effect

Average global temperature is 57⁰F.

Venus: The Extreme Greenhouse Effect

Heat is trapped by the thick CO2 atmosphere. Temperatures reach 750⁰F.

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• Defined: Precipitation with a below normal pH

• Cause:– Fossil fuel pollution rises

into the air & then falls as rain

• Effects:– Waterways more acidic– Kills plant and animal life

• Solutions:– Reduce fossil fuel usage– Add buffer (base) to

waterways 16

SO2

NO

NO

Nitric acid

Sulfuric acid

• Defined: pollution in water supplies

• Causes:– Waste– Medicines– Agricultural Runoff

– fertilizers– pesticides

• Problems:– Species lost– Ecosystems harmed

• Solutions:– Manage waste

WATER POLLUTION

20

WATER POLLUTION AFFECTS ECOSYSTEMS

• Indicator species: Give sign of ecosystem’s health• Example:

• Amphibians • Frogs are good

indicator species because their skin is water permeable.

• Top predators• Solution: Waste Management 21

• Defined: Accumulation of toxins in the food chain

• Fat soluble pollutants move up food chain.– These pollutants stay

in the body fat of an organism

– Predators eat contaminated prey

– Pollution accumulates at each level of the food chain

• Top consumers, including humans, are most affected.

Biomagnification

22

Deforestation• Defined: Clearing of

forested areas• Causes:

Harvesting/destroying forests for high demand:– Wood products– Creating farmland

• Effects:– Species lost– Excess CO2 released

• Solutions:– Recycle– Improved farming

techniques 23

24

Introduced & Invasive Species • Defined: Foreign organisms are

introduced to a new habitat– Invasive: harms native species

• Cause:– Foreign species introduced to

new environment• Effects:

– Foreign species outcompete native species

– Food webs unbalanced– Economic damage

• Solutions:– Laws preventing foreign goods

into new countries– Introduce predators Kudzu vines

Zebra mussels

Mice

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What is being done?

• The Environmental Protection Agency (EPA) – Created in 1970– Works to protect species

• Clean Water Act• Clean Air Act• Endangered Species Act

– This recovered the bald eagle– Those listed are called “Umbrella

Species”– Entire habitats protected

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Review1) CFCs are manmade chemical responsible for the destruction of the2) Which gas is a main contributor to the greenhouse effect?3) Crop damage and cancers are caused by an excess amount of which type of

energy? __________________4) Name the big three fossil fuels:5) Which planet has excess temperatures because of a thick CO2 atmosphere?

6) What is smog? 7) How are pollutants passed through the food chain?8) Where is ozone gas harmful to life? 9) Where is ozone gas helpful to life? 10) What makes a resource nonrenewable?11) Food webs become unbalanced as a result of the introduction of which type of

organisms?12) What is an umbrella species?