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Human Impact

How do humans impact their environment?

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Human Impact can take several forms

• Resource Use

• Land abuse

• Pollution

• Loss of Biodiversity

• Ozone Depletion

• Greenhouse Effect

• Global Warming

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Resource Use

• Whether a resource is “renewable" or “nonrenewable" is about how long nature takes to renew it.

• Renewable – can be renewed by nature, includes energy sources that do not consume fuel

• Renewable resources are NOT unlimited, they can be abused

• Plants, animals

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Resource Use cont.

• Nonrenewable Resources –

• cannot be replenished by nature within our lifetimes - are limited in supply

• fossil fuels, metals, other minerals

• Sustainable Use – using natural resources at a rate that does not deplete them

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Land Abuse

1. Soil Erosion

2. Desertification – farming and drought turn dry grasslands into desert

3. Deforestation

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Pollution

Acid Rain - burning of fossil fuels release N2 & S which combine with water vapor to form nitric and sulfuric acid

Acid Rain

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Pollution – Biological Magnification• Biological Magnification – concentration of

harmful substances increase in organisms as chemical travel in the food web

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Loss of Biodiversity

• Biodiversity is the variety of living things.

• CAUSES of Loss:

• Endangered species – species that is highly vulnerable to extinction

• Habitat loss – physical reduction in suitable places to live

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Ozone Depletion

• layer of ozone (O3) is normally present in Earth’s upper atmosphere

• prevents much of UV light emitted by sun from reaching Earth’s surface

• Chlorofluorocarbons (CFCs) – in polar atmosphere, CFCs act as catalyst that enable UV light to break apart ozone materials

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• What does the Ozone Layer do?

– Ozone absorbs 99% of the harmful ultraviolet (UV) radiation.

•Without the Ozone Layer

Most of the harmful UV radiation will penetrate the

atmosphere.

This can cause skin cancer and eye problems but DOES NOT cause Global Warming!

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Greenhouse Effect

• heat is retained by the layer of gases (CO2, CH4, etc) forming the atmosphere. This is a Natural Process!

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Global Warming

• Increase in average temperature of biosphere • over past 120 years, global temp. has risen .5o C• CAUSES – human activities have caused global

warming by adding CO2 and other greenhouse gases to the atmosphere

• RESULT – atmospheric greenhouse gases retain more heat and average temp rises. Can cause sea level to rise and disrupt weather patterns