Human Impacts on the Environment

People

Population All the members of a

species living in a given area

Human population has exploded over the last couple centuries due to improved health

care, clean water, etc

Carrying Capacity The largest number of individuals of a

given species that Earth’s resources can support and maintain for a long period of time populations that exceed carrying capacity

will begin to die off due to lack of resources (food, water, space)

Impacts on Land

Humans Using Land - Forest Resources Trees are cut down to make wood and paper

products, and to clear land for development

Deforestation removal of large area of forests for human purposes

Effects of Deforestation Habitat destruction

Soil erosion plant roots hold soil in

place; without plants the soil erodes away

Air quality less oxygen and more

carbon dioxide in the air

Humans Using Land - Agriculture

Large areas of land cleared for farming and cattle grazing

Effects of Agriculture Fertilizers

add excess nitrogen to the soil pollute groundwater

Desertification the development of desert-like

conditions due to human activities can occur due to soil erosion

and/or over farming

Humans Using Land - Mining Removal of rocks and minerals from the

ground

Effects of Mining disturbing habitats changes the landscape water pollution from runoff

Construction and Development Urbanization

the movement of human populations into cities

Urban Sprawl the development of land

for houses and other buildings near a city

Effects of Urbanization habitat destruction reduced water quality

due to increased runoff

Positive actions Preservation

Governments can protect land by setting aside wild areas

There are laws about how the resources there can be removed

Forests are complex but they can be managed to preserve the ecosystem Select-cutting- only certain trees in

one area are cut down rather than lots of trees or all the trees

Reforestation- replanting trees that have been cut or burned down

Reclamation- restoring land that has been disturbed by mining

Positive actions Green Spaces

Cities use green spaces to create natural environments in urban settings

They provide places for recreation for people and habitat for wildlife

They reduce runoff and improve air quality as plants take up extra carbon dioxide

Positive actionsReusing,

Reducing, & Recycling

Composting Reduces the amount

of trash that ends up in landfills.

It involves mixing food scraps, leaves, and grass clippings and adding the decayed product to soil.

Impacts on Water

Water as a Resource

48%34%

11%

5% 2% Power plantsIrrigation of cropsPublic supplyIndustryOther

most water is used in power plants to generate electricity

Sources of Water PollutionPoint-Source Pollution pollution from a single

source that can be identified ex. oil spills, mining

runoff

Nonpoint-Source Pollution

pollution from several widespread sources that cannot be traced to a single location ex. agricultural and

urban runoff

Most of the United States’ water pollution is nonpoint-source

Positive Actions National Initiatives:

Clean Water Act regulates sources of

water pollution

Safe Drinking Water Act protects supplies of

drinking throughout the country

How You Can Help: Reduce use of

harmful chemicals

Dispose of waste safely

Conserve water

Impacts on the Atmosphere

Types of Air Pollution - Smog

Smog nitrogen and carbon compounds are

released from burning fossil fuels these compounds react with sunlight to

make ozone and other chemicals

Types of Air Pollution – Acid Rain

Acid Rain rain or snow that has a

lower pH than that of normal rainwater

makes soil more acidic, making it difficult for plants to survive

Other Types of Air Pollution Particulate Matter

mix of both solid and liquid particles in the air ex. smoke, dust

CFCs destroy ozone

molecules

Carbon Monoxide released from cars and

forest fires

Global Warming burning fossil fuels releases excess

amounts of carbon dioxide into the air

this can lead to an increase in Earth’s average surface temperature

Effects of Global Warming Melting of ice caps

and a rise in sea level

More storms due to higher ocean temperatures

Extinction of cold-weather species

The Greenhouse Effect The natural process that occurs when

gases in the atmosphere absorb and reradiate thermal energy from the Sun

Increased carbon dioxide traps more heat in the atmosphere

Health Disorders Air pollution can cause

respiratory problems, including asthma attacks, in which the passageways in the lungs become narrower and breathing becomes difficult.

The government measures and reports air quality using the Air Quality Index, which is a scale that ranks the level of ozone and other pollutants.

Positive actions Montreal Protocol

Countries around the world have agreed to phase out CFC’s and to lower emissions of green house gases to help reduce problems due to Air pollution

Clean Air Act Since it was passed in 1970,

we have seen a 50% reduction in pollutants that cause acid rain and a 90% reduction in air pollution from factories.

Positive actions Using Renewable

Energy Renewable resources

such as solar power, wind power, and geothermal energy helps reduce air pollution

Using Less Energy Helps reduce pollution

and improve the quality of all our important resources: water, air, soil