Transcript 16.1 Human Population Growth And Natural Resources

16.1 Human Population Growth And Natural
Resources
KEY CONCEPT
As the human population grows, the demand for
Earth’s resources increases.
16.1 Human Population Growth And Natural
Resources
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
16.1 Human Population Growth And Natural
Resources
Earth’s human population continues to grow.
• Earth’s human carrying capacity is unknown.
16.1 Human Population Growth And Natural
Resources
• 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.
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
• 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.
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
• 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
16.1 Human Population Growth And Natural
Resources
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
16.1 Human Population Growth And Natural
Resources
• Several factors affect the size of the ecological footprint.
– amount and efficiency of resource use
– amount and toxicity of waste produced
16.1 Human Population Growth And Natural
Resources
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?
16.1 Human Population Growth And Natural
Resources
KEY CONCEPT
Fossil fuel emissions affect the biosphere.
16.1 Human Population Growth And Natural
Resources
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
16.1 Human Population Growth And Natural
Resources
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
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
Atmospheric Hazard
Great Smog
of 1952
16.1 Human Population Growth And Natural
Resources
• 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
16.1 Human Population Growth And Natural
Resources
Acid Precipitation
pH Scale
16.1 Human Population Growth And Natural
Resources
Precipitation pH values for U.S. in 2003
16.1 Human Population Growth And Natural
Resources
Damage
to
Forests
by
Acid
Precipitation
16.1 Human Population Growth And Natural
Resources
Acid Rain
Accelerates
Chemical
Weathering
of Stone
Monuments
and Structures
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
• 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
16.1 Human Population Growth And Natural
Resources
• Global warming refers to the trend of increasing global
temperatures.
• False color animation
• Global Warming Video
North Pole
16.1 Human Population Growth And Natural
Resources
• 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)
16.1 Human Population Growth And Natural
Resources
KEY CONCEPT
Pollution of Earth’s freshwater supply threatens
habitat and health.
16.1 Human Population Growth And Natural
Resources
Water pollution affects ecosystems.
• Pollution can put entire freshwater ecosystems at risk.
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
• Indicator species provide a sign of an ecosystem’s health.
– amphibians
– top predators
Also known as a bioindicator
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
KEY CONCEPT
The impact of a growing human population threatens
biodiversity.
16.1 Human Population Growth And Natural
Resources
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
16.1 Human Population Growth And Natural
Resources
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
16.1 Human Population Growth And Natural
Resources
• Habitat corridors are a solution to the problem.
– corridors can be road overpasses or underpasses
– allow species to move between different areas of
habitat
16.1 Human Population Growth And Natural
Resources
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.
16.1 Human Population Growth And Natural
Resources
• Invasive species often push out native species.
– Burmese python (Florida Everglades)
16.1 Human Population Growth And Natural
Resources
• Invasive species often push out native species.
– mice (Australia)
16.1 Human Population Growth And Natural
Resources
• Invasive species often push out native species.
– kudzu (southeastern United States)
16.1 Human Population Growth And Natural
Resources
KEY CONCEPT
Conservation methods can help protect and
restore ecosystems.
16.1 Human Population Growth And Natural
Resources
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
16.1 Human Population Growth And Natural
Resources
• 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
16.1 Human Population Growth And Natural
Resources
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
16.1 Human Population Growth And Natural
Resources
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
16.1 Human Population Growth And Natural
Resources
• The National Park Service
helps manage public
lands.
• The park system includes
over 390 areas, covering
84 million acres.
16.1 Human Population Growth And Natural
Resources
• There are several ways that people can help protect the
environment.
– control population growth
– develop sustainable technology and practices
– protect and maintain ecosystems