key concept as the human population grows, the demand for

16.1 Human Population Growth And NaturalResources

KEY CONCEPT As the human population grows, the demand forEarth’s resources increases.


Earth’s human population continues to grow.

• Earth’s human carrying capacity is unknown.


• Technology has helped to increase Earth’s carryingcapacity.– gas-powered farm equipment– medical advancements


The growing human population exerts pressure onEarth’s natural resources.

• Nonrenewable resources are used faster than they form.– coal– oil


• Renewable resources cannot be used up or can replenishthemselves over time.– wind– water

– sunlight• Growing use of

nonrenewableresources maylead to a crisis.

• Resources mustbe properlymanaged.


Effective management of Earth’s resources will help meetthe needs of the future.

• Earth’s resources must be used responsibly. • Careless use of resources makes them unavailable to

future generations.• Easter Island is

an example ofirresponsibleresource use.


• An ecological footprint is the amount of land needed tosupport a person.

• The land must produce and maintain enough– food and water

– shelter

– energy– waste


• Several factors affect the size of the ecological footprint.– amount and efficiency of resource use – amount and toxicity of waste produced

16.2 Air Quality

KEY CONCEPT Fossil fuel emissions affect the biosphere.

16.2 Air Quality

Pollutants accumulate in the air.

• Pollution is any undesirablefactor added to the air, water, orsoil.

• Smog is one type of air pollution.

– sunlight interacts withpollutants in the air

– pollutants produced by fossilfuel emissions

– made of particulates andground-level ozone

16.2 Air Quality

• Smog can be harmful to human health.• Acid rain is caused by fossil fuel emissions.

– produced when pollutants in the water cycle cause rainpH to drop

– can lower the pH of a lake or stream– can harm trees

16.2 Air Quality

Air pollution is changing Earth’s biosphere.

• The levels of atmospheric carbon dioxide rise and fall overtime.

• High levels of carbon dioxide are typical of Earth’s warmerperiods.

16.2 Air Quality

• The greenhouse effect slows the release of energy fromEarth’s atmosphere.– sunlight penetrates Earth’s atmosphere– energy is absorbed and reradiated as heat

– greenhouse gases absorb longer wavelengths

– Greenhousegas moleculesrereleaseinfraredradiation

methane (CH4) water (H2O)

carbon dioxide(CO2)

16.2 Air Quality

• Global warming refers to the trend of increasing globaltemperatures.

North Pole

16.3 Water Quality

KEY CONCEPT Pollution of Earth’s freshwater supply threatenshabitat and health.

16.3 Water Quality

Water pollution affects ecosystems.

• Pollution can put entire freshwater ecosystems at risk.

16.3 Water Quality

• Indicator species provide a sign of an ecosystem’s health.– amphibians– top predators

16.3 Water Quality

Biomagnification causes accumulation of toxins in thefood chain.

• Pollutants can move up thefood chain.

– predators eat contaminatedprey

– pollution accumulates ateach stage of the food chain

• Top consumers, includinghumans, are most affected.

16.4 Threats To Biodiversity

KEY CONCEPT The impact of a growing human population threatensbiodiversity.


Preserving biodiversity is important to the future of thebiosphere.

• The loss of biodiversity has long-term effects.

– loss of medical and technological advances– extinction of species– loss of ecosystem stability


Loss of habitat eliminates species.

• Habitat fragmentation prevents an organism fromaccessing its entire home range.– occurs when a barrier forms within the habitat– often caused by human development


• Habitat corridors are a solution to the problem.

– corridors can be road overpasses or underpasses

– allow species to move between different areas ofhabitat


Introduced species can disrupt stable relationships in anecosystem.

• An introduced species is one that is brought to anecosystem by humans.

– accidental

– purposeful

• Invasive speciescan have anenvironmentaland economicimpact.


• Invasive species often push out native species.– Burmese python (Florida Everglades)


• Invasive species often push out native species.– mice (Australia)


• Invasive species often push out native species.– kudzu (southeastern United States)

16.5 Conservation

KEY CONCEPT Conservation methods can help protect andrestore ecosystems.

16.5 Conservation

Sustainable development manages resources for presentand future generations.

• Sustainable development meets needs without hurtingfuture generations.

– resources meet current needs

– resources will still be available for future use

16.5 Conservation

• The timber industry has started to adopt sustainablepractices.

• Global fisheries have adopted several sustainablepractices.– rotation of catches – fishing gear review

– harvest reduction

– fishing bans

16.5 Conservation

Conservation practices focus on a few species but benefitentire ecosystems.

• The Endangered Species Actworks to protect individualspecies from extinction.

• A listed species is often calledan umbrella species.– the habitat in which the

species lives must beprotected

– other species are protectedbecause they share theecosystem

16.5 Conservation

Protecting Earth’s resources helps protect our future.

• The Environmental Protection Agency (EPA) was createdin 1970.

• The EPA develops policies and regulations to protect theenvironment.

• Legislation helps to protect the environment andendangered species.– Clean Air Act– Clean Water Act

– Endangered Species Act

16.5 Conservation

• The National Park Servicehelps manage publiclands.

• The park system includesover 390 areas, covering84 million acres.

16.5 Conservation

• There are several ways that people can help protect theenvironment.– control population growth– develop sustainable technology and practices

– protect and maintain ecosystems

key concept as the human population grows, the demand for

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