Download 16.1 Human Population Growth And Natural Resources

16.1 Human Population Growth And Natural
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KEY CONCEPT
As the human population grows, the demand for
Earth’s resources increases.
16.1 Human Population Growth And Natural
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Earth’s Carrying Capacity
• We refer to the amount of people that Earth can support
as the Carrying Capacity of Earth.
• Thomas Malthus (Late 1700’s) – Claimed that the human
population was growing faster than Earth’s resources
could support.
– Malthus’ prediction was off because of the advances
in technology.
• US Population Over Time
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Earth’s human population continues to grow.
• Earth’s human carrying capacity is unknown.
16.1 Human Population Growth And Natural
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• Technology has helped to increase Earth’s carrying
capacity.
– gas-powered farm equipment – Increased world food
production.
– medical advancements – Increase population growth.
– Antibiotics and antiseptics have lowered infant
mortality and the spread of disease.
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The growing human population exerts pressure on
Earth’s natural resources.
• Nonrenewable resources are used faster than they form.
they cannot be replace in our lifetime.
– coal
– oil
• The growing use of these limited resources will lead to
energy crises in the decades ahead unless technologies
are developed to use other forms of energy.
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• Renewable resources cannot be used up or can replenish
themselves over time.
– wind
– water
– sunlight
• Growing use of
nonrenewable
resources may
lead to a crisis.
• Resources must
be properly
managed.
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Effective management of Earth’s resources will help meet
the needs of the future.
• Earth’s resources must be used responsibly.
• Careless use of resources makes them unavailable to
future generations.
• Plants for
example can
be renewable
if managed.
• Easter Island is
an example of
irresponsible
resource use.
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Easter Island
• Inhabitants cut down the trees faster than they could
grow back.
• Without trees, there was no wood for shelter and building
boats.
• Without boats, there was no fishing and therefore no
food.
• As a result, people disappeared for Easter Island.
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• An ecological footprint is the amount of land needed to
support a person.
– The United States uses more resources and produces
more waste than any other country on Earth.
• The land must produce and maintain enough
– food and water
– shelter
– energy
– Waste
– Global Environmental Issues Videos
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Ecological Footprint
• The size of an Ecological Footprint depends on:
– Amount and efficiency of resource use.
– Amount and toxicity of waste produced.
• Ecological Footprint Calculator
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• Several factors affect the size of the ecological footprint.
– amount and efficiency of resource use
– amount and toxicity of waste produced
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Ecological Footprint
• Many developing countries like China and India have
small ecological footprints per person, but large
populations.
• Developed and Developing Nations
– As the world population continues to grow, humans
face the challenge of living sustainably and preserving
Earth’s resources for our future and future
generations.
– What can we do individually, nationwide, and globally
to preserve our future?
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KEY CONCEPT
Fossil fuel emissions affect the biosphere.
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Pollutants accumulate in the air.
• Pollution is any undesirable factor
added to the air, water, or soil.
– Ex. Microscopic air particles,
waste products from factories
and sewers, household
chemicals, etc.
• Smog is one type of air pollution.
– sunlight interacts with pollutants
in the air
– pollutants produced by fossil fuel
emissions such as burning gas
and oil
– made of particulates and
ground-level ozone
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Smog and Ozone
• Particulates – Microscopic bits of dust, metal, and
unburned fuel.
– 1-10 microns in size.
– Can stay in the atmosphere for weeks before settling.
– Can be inhaled and can cause many different types of
health problems.
– Fossil Fuels
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Smog and Ozone
• Ground-level Ozone – Produced when nitrogen dioxides
(NO2) from fossil fuel combustion combine with oxygen
(O2) to form ozone (O3).
• Ozone is harmful to organisms at ground level, but plays
a critical role in protecting Earth’s biosphere from harmful
UV rays from the sun.
– CFC pollution has caused holes in our ozone layer.
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Atmospheric Hazard
Great Smog
of 1952
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• Smog can be harmful to human health.
• Acid rain is caused by fossil fuel emissions.
– produced when pollutants in the water cycle cause rain
pH to drop
– can lower the pH of a lake or stream
– can harm trees
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Acid Precipitation
pH Scale
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Precipitation pH values for U.S. in 2003
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Damage
to
Forests
by
Acid
Precipitation
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Acid Rain
Accelerates
Chemical
Weathering
of Stone
Monuments
and Structures
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Air pollution is changing Earth’s biosphere.
• The levels of atmospheric carbon dioxide rise and fall over
time.
• High levels of carbon dioxide are typical of Earth’s warmer
periods.
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• The greenhouse effect slows the release of energy from
Earth’s atmosphere.
– sunlight penetrates Earth’s atmosphere
– energy is absorbed and reradiated as heat
– greenhouse gases absorb longer wavelengths
– Greenhouse
carbon dioxide
(CO )
gas molecules
methane (CH )
water (H O)
rerelease
infrared
radiation
2
4
2
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• Global warming refers to the trend of increasing global
temperatures.
• False color animation
• Global Warming Video
North Pole
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• Greenhouse gases.
• Sunspots that are exploding cause
the temperature to rise on earth.
• Volcanic eruptions naturally release
greenhouse gases; also damage
plants that filter out CO2.
• Earth’s orbit has changed, resulting
in changes of temperature,
depending on distance from the sun.
• Methane gas is naturally released
from Arctic Tundra and Wetlands.
• Animal flatulence and manure.
(methane)
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KEY CONCEPT
Pollution of Earth’s freshwater supply threatens
habitat and health.
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Water pollution affects ecosystems.
• Pollution can put entire freshwater ecosystems at risk.
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Water Pollution Affects Ecosystems
• Runoff from farms and cities contain toxic chemicals and
debris that can contaminate freshwater ecosystems.
– Ex. Detergents and fertilizers pollute lakes and
stimulate plant and algae growth.
• Can result in Eutrophication – Suffocation a lake due to lack
of oxygen.
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• Indicator species provide a sign of an ecosystem’s health.
– amphibians
– top predators
Also known as a bioindicator
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Indicator Species
• Frogs – Skin is water permeable and direct contact with
pollutants can cause deformities such as extra arms and
legs, as well as body tumors.
– Aquatic species show direct effects of pollution.
– Terrestrial species show environmental impacts
differently.
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Indicator Species
• Forster’s Tern – A coastal bird that occupies a niche at
the top of the food web.
– Eats fish.
– Large amounts of chemical contaminants have been
found in the tissues of dead terns.
– Decrease in populations of Terns could disrupt the
balance of the aquatic ecosystem.
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Biomagnification causes accumulation of toxins in the
food chain.
• Pollutants can move up the
food chain.
– predators eat contaminated
prey
– pollution accumulates at
each stage of the food chain
• Top consumers, including
humans, are most affected.
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Biomagnification
• Biomagnification caused decreasing Bald Eagle
populations.
– Caused by spraying the pesticide DDT.
– Resulted in eggs being laid with thin shells.
• Birth rates decreased dramatically
– DDT was banned in the U.S. and Bald Eagles have
been making a comeback nationwide.
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Biomagnification
• Other victims of Biomagnification
– Beluga whale – Some carcasses have been treated as
hazardous waste
– Humans – Small amounts of PCB’s have been found
in the blood of newborn babies.
• May affect the growth and development of young children.
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KEY CONCEPT
The impact of a growing human population threatens
biodiversity.
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Preserving biodiversity is important to the future of the
biosphere.
• The loss of biodiversity has long-term effects.
– loss of medical and technological advances
– extinction of species
– loss of ecosystem stability
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Loss of habitat eliminates species.
• Habitat fragmentation prevents an organism from
accessing its entire home range.
– occurs when a barrier forms within the habitat
– often caused by human development
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• Habitat corridors are a solution to the problem.
– corridors can be road overpasses or underpasses
– allow species to move between different areas of
habitat
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Introduced species can disrupt stable relationships in an
ecosystem.
• An introduced species is one that is brought to an
ecosystem by humans.
– accidental
– purposeful
• Invasive species
can have an
environmental
and economic
impact.
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• Invasive species often push out native species.
– Burmese python (Florida Everglades)
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• Invasive species often push out native species.
– mice (Australia)
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• Invasive species often push out native species.
– kudzu (southeastern United States)
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KEY CONCEPT
Conservation methods can help protect and
restore ecosystems.
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Sustainable development manages resources for present
and future generations.
• Sustainable development meets needs without hurting
future generations.
– resources meet current needs
– resources will still be available for future use
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• The timber industry has started to adopt sustainable
practices.
• Global fisheries have adopted several sustainable
practices.
– rotation of catches
– fishing gear review
– harvest reduction
– fishing bans
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Conservation practices focus on a few species but benefit
entire ecosystems.
• The Endangered Species Act
works to protect individual
species from extinction.
• A listed species is often called
an umbrella species.
– the habitat in which the
species lives must be
protected
– other species are protected
because they share the
ecosystem
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Protecting Earth’s resources helps protect our future.
• The Environmental Protection Agency (EPA) was created
in 1970.
• The EPA develops policies and regulations to protect the
environment.
• Legislation helps to protect the environment and
endangered species.
– Clean Air Act
– Clean Water Act
– Endangered Species Act
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• The National Park Service
helps manage public
lands.
• The park system includes
over 390 areas, covering
84 million acres.
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• There are several ways that people can help protect the
environment.
– control population growth
– develop sustainable technology and practices
– protect and maintain ecosystems