Chapter 19

Our Impact on Land

19.1 Population Impact on the Environment

Human Population Explosion Earth was believed to be a boundless cornucopia

of resources Endless supply of metals, fossil fuels, and fertile

soil Today we know that is not true Earth has a Carrying Capacity Carrying Capacity: the maximum number of

individuals of a particular species an area can support

Before 1800’s: Human population relatively small Minimum resources were used Much less waste was produced Currently, human population is growing at an

alarming rate

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U.S. Population World Population

Human Population:

Population: the total number of individuals of a particular species in a defined area

Over the past 200 years Humans have been undergoing a Population Explosion.Population Explosion: rapid, uncontrolled

population growth

Why Our Population is Increasing:

Modern medicine: Reduced infant death drastically Increased ability to reproduce (Fertility Drugs) Allows people to live longer Modern Sanitation: Drinking water cleaned before use Wastes disposed of better People are cleaner Better nutrition: Food better distributed & more available Aid given to area of famine

Environmental Impact

Increasing population brings with it many changes 1) Increased demands for resources 2) Increased housing requirements 3) Increased waste production By the time you are 75… You will produce enough garbage to equal the mass

of 16 elephants = 47, 000 kg You will consume enough water to fill 662,000

bathtubs = 163,000,000 L Americans use 5x more energy than anyone else

Our Daily Activities

Many resources required: Electricity drives our daily lives Mainly produced by burning fossil fuels (coal & oil) Water is required for drinking, cooking, & cleaning Once used, water is cleaned before returning to nature Food must be grown Requiring large amounts of land (fields, pastures,

fisheries, etc.) Wood used for building, packaging, & personal products Trees need to be harvested Plastics used for almost everything, refined from crude

oil Metals must be mined & refined for use

Effects of our Daily Activity

Mining: metals & fossil fuels extracted from the Earth Destroys Ecosystems (removes trees, soils, & rock)

Farming & Lumbering: Topsoil Erosion Chemical fertilizers, pesticides & herbicides used

Material Production: Pollution of water & air Use of large volumes of waters

Solid & Liquid waste: Landfills, Water treatment & Sewage treatment plants

The Future:

As population grows, so will our demands on nature More land required for housing Shrinking forests Overflowing garbage dumps Vanishing Wildlife Increased disease Less available water

We are the problem, We must also be the solution

19.2 Using the Land

Farming: The Earth has 145 million square km of land 15 million square km used for agriculture

20 % of all humans go hungry Millions starve to death each year

Farmers constantly try to increase crop yield Better land use tactics Use higher-yield or genetically engineered seeds Chemical fertilizers Herbicides & Pesticides

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Agricultural Damage:

Chemicals can contaminate the soil Chemicals from fertilizers, herbicides, & pesticides Oils & Fuels used in machinery

Plowing land exposes soil to the elements Increases erosion by wind & water

Grazing Livestock Cattle & Sheep graze on grasslands Overgrazing: removal of vegetation by livestock

Minimizing Agricultural Damage:

Reducing Erosion: Strip Cropping: fields set up in sections containing different

crops Crop Rotation: Changing crops planted yearly, creating a

revolving cycle Contour Plowing: following the lay of the land, plowing across

the sides of hills (not up & down) Terracing: Creating steps to grow crops Shelter Belts: (windbreaks) tree lines planted to slow down

winds Integrated Pest Management: IPM

Natural predators control pests, reducing need for chemical sprays

Ex: Ladybugs to control aphids

Strip Cropping & Crop Rotation

Contour Plowing & Terracing:

Shelter Belts:

Cutting Trees:

Lumber has many uses Paper products, building materials, & fuel

Timbering is an International business Tropical Rain forests are harvested for their unique woods Whole forests are cut down

Every year an area the size of PA is clear cut Estimated 50,000 species became extinct due to

deforestation Deforestation: the process of removing entire forests

Reducing plant life decreases available oxygen Also increases Carbon Dioxide amounts

Carbon Dioxide: major Greenhouse gas (leads to Global Warming)

Landfills:

Areas where garbage is disposed & buried Many types of landfills: most common = Sanitary Landfills

Governed by a strict set of regulations Before dumping, a liner must be installed (Prevents water

pollution) Each days garbage is covered by a layer of dirt Methane is vented off as well

Hazardous Wastes:

Any waste that is poisonous, causes cancer, radioactive, or generally harmful to organisms

These waste products can be from industry or homes

They do not breakdown quickly & remain dangerous Special care must be taken in disposing of these

wastes

Structures, Mines, & Natural Environments

Concrete & Asphalt are replacing grass & trees Buildings, roads, parking lots, & sidewalks absorb large

amounts of solar radiation (Heat) Creates microclimates: Cities have higher temperatures,

different wind patterns, and cloud bursts Reduces water absorption into the ground Increases water pollution

Strip Mining: removes vegetation over large areas Deforestation decreases clean air & increases

desertification Mining produces runoff & pollution

Natural Preserves

Not all land is being decimated by human needs Some areas are set aside

US National Parks & Forests PA State Parks & Game lands Schuylkill County County Park (Sweet Arrow Lake Area)

All are protected from industrial & municipal growth Left to be natural retreats for wildlife (& humans)

US National Parks Webcam Directory

Conserving Resources:

We live in a disposable society Everything is designed to be used, discarded & replaced

Material Packaging: Paper & Plastics Planned Obsolescence: material designed to become

quickly outdated or unusable Automobiles: designed to last 10 years Computers: technology outdated before purchase Watches: last a year or two & stop working

Continual cycle of production established Continual need for materials present

Conservation:

The careful management & use of resources reducing harmful effects on the environment

THE 4 R’s: Reduce: The US has 5% the world’s population, we use

25% of the world’s resources… Reuse: Find more uses for things

Old cloths can become cleaning rag & towels Recycle: Many materials can be reprocessed

Metals, plastics, paper, etc. all recyclable Composting: Pile leaves & other plant material to

decompose Replace: Use natural, renewable products instead of

processed materials

The Population Outlook:

It is unlikely that Earth’s population will decline Dilemma: Increasing population = decreased resources How do we deal with the problem?

Several Options: (Not all good) Do nothing: uses what we want, and don’t worry about it Look toward our future: cut back a little so there is

something left for later Prepare for future generations: move toward renewable

resources, & less destructive behavior, even if it inconveniences us now

19.3 Should recycling be required?

Any object that can be reprocessed = recyclable What’s in your trash?

80 % of all trash can be recycled or composted Paper, Plastic, Metals & Glass all recyclable

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Did You Know?

Paper products = 50% of your weekly garbage Recycling paper saves trees, uses less water & creates

less pollution than making “new” paper Recycling one aluminum can saves enough energy to run

a TV for three hours Recycling 20 cans required the same amount of energy

needed to make one new can from raw aluminum

Two Points of View:

Everyone agrees: recycling is good for the Environment It saves landfill space, energy, & natural resources Decreases the need for mining, cutting trees, & oil drilling

Should recycling be mandatory? The US should require residential recycling

Many people do not recycle because they “never got into the habit”

There is not a big push in industry for “reuse” facilities Only 17 states have recycling laws Some states pay deposits on cans, bottles, etc.

No: Voluntary Recycling only Many people already recycle and the trend is increasing Some people refuse to recycle: They claim they are

protecting jobs of miners & “new” material production workers