Human Impact

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Human Impact
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Human Impact

• Human Population Growth and Natural Resources
• Air Quality
• Water Quality
• Threats to Biodiversity
• Conservation

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Human Population Growth and Natural Resources

• Why does the human population keep growing?
• (Sanitation, Agriculture, Medicine)

According to this chart, when will humans reach
carrying capacity?
When the slope of the line 0
This is completely hypothetical. Carrying
capacity could be 10, 20, or even 50 billion. In
fact maybe we already passed it!
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Ecological FootprintThe amount of land
necessary to produce and maintain enough natural
resources and store waste for an individual
person.

• The size of the footprint depends on a number of
  factors
• Bioproductive Land- land required to produce
  crops, grazing (pasture), timber (forest) etc.
• Bioproductive Sea- sea area required to provide
  fish and seafood.
• Energy Land- forest required to absorb CO2
  emissions to stabilize levels in atmosphere.
• Built Land- land already used up by
  buildings/roads
• Biodiversity- land needed to preserve natural
  flora/fauna.

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Ecological Footprint
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Ecological Footprint
The average Americans ecological footprint is
around 9.7 hectares. (1 hectare 10,000 square
meters) Thats larger than 24 football fields. We
may have a large footprint, but other countries
have many more feet.
US population 301,140,000 China
1,321,852,000 India 1,129,866,000
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Human pressure on natural resources

• Two types of natural resources
• Renewable
• Nonrenewable

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Human pressure on natural resources

• Two types of natural resources
• Renewable resources that cannot be used up, or
  replenish themselves over time.
• Nonrenewable resources that are used up faster
  than they are formed.

Wind
Wood
Fresh-water
Fish
Coal
Oil
Nuclear
Natural Gas
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Coal and Oil Formation

• Both are Fossil Fuels remains of plants and
  animals that died anywhere from 400 million to 1
  million years ago.

Called Buried Sunshine because organisms stored
energy from the sun, buried under sediment over
time. The heat and pressure from the overlying
sediment creates the fuel. Both are made largely
of carbon, which gives off a lot of energy when
burned.
How is Coal different than Oil?
Coal is formed from organisms (mostly plants)
that lived on land typically in swamps. Oil is
formed from organisms (mostly plankton) that
lived in the oceans.
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Air Quality

• Burning fossil fuels releases compounds that
  pollute the biosphere.
• Forms of Air Pollution
• Smog
• Ozone
• Acid Rain

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Smog

• A type of air pollution caused by the interaction
  of sunlight with pollutants produced by fossil
  fuel emissions.
• Full of particulates, which are microscopic bits
  of dust, metal, and unburned fuel (1-10 microns
  in size).
• These can be inhaled and cause many health
  problems.

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Ozone

• NO2 produced in fossil-fuel combustion reacts
  with O2 to create O3 (Ozone). Ground level ozone
  is very dangerous to living things.

Can cause asthma, emphysema, and is very harmful
to plants
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Acid Rain

• Type of precipitation (water formation) produced
  when pollutants in the water cycle cause rain pH
  to drop below normal levels.

pH amount of H ions in a solution. Lots of H
Low pH pH scale 1-14 Neutral pH 7 Normal Rain
slightly acidic (5.6) Acid Rain any pH less than
this. Threatens water supplies and plant life.
Can result in growth rate declines. Makes plants
more vulnerable to disease and weather.
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Greenhouse Effect
Light energy from the sun (solar radiation) is
either reflected or absorbed by the Earth. When
it is absorbed it is converted into heat energy
(infrared radiation). That heat energy either
escapes the Earth through the atmosphere, or gets
absorbed by greenhouse gases and reflected back
down. This is how heat is trapped within the
troposphere and how the Earth stays warm.
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Greenhouse Effect

• Greenhouse gasses include
• Water (H2O)
• Methane (CH4)
• Carbon Dioxide (CO2)
• Nitrous Oxide (N2O)
• The first 3 are very natural, and in
• fact necessary to keep the Earth
• warm.

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Global Warming
As more CO2 is added to the atmosphere, it traps
more heat reflected from the Earth and rises the
average global temperature.
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Global Warming Effects

• High global temperatures
• (Heat Waves)
• Increased drought, extreme weather.
• Raising sea levels caused by melting ice.
• Acidification of the ocean.

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Water Quality

• Pollution can also have major impacts on water
  ecosystems.
• Detergents and fertilizers can stimulate plant
  and algae overgrowth in lakes.
• Medical waste can expose fish to hormones that
  can cause them to change gender.
• Amphibians with water permeable skin come into
  direct contact with pollutants, that can cause
  deformities like extra arms and legs.

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Indicator Species

• These are all examples of indicator species, a
  species that provides a sign, or indication of
  the quality of the ecosystems environmental
  conditions.
• Algal blooms are indications of negative effects
  on the ecosystem.
• Detergents and fertilizers provide nutrients for
  large algal populations that then suck all the
  oxygen out of the area, killing anything else in
  the area.
• This keeps detritivores from breaking down waste
  materials, and the lake or pond will eventually
  fill up, which is called eutrophication.

Caspian Sea
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Eutrophication
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Biomagnification

• Pollutants can move from one organism to another
  through a process called biomagnification. This
  occurs when a pollutant moves up the food chain
  as predators eat prey, and ends up accumulating
  in higher concentrations in the bodies of
  predators.
• Scientists measure pollutants this way in parts
  per million (ppm).

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Biodiversity

• Biodiversity is the variety of life within an
  area.
• An ecosystems health is typically measured in
  how much biodiversity it has.
• The loss of even a single species can harm the
  overall stability of an ecosystem

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Biodiversity
The most biodiversity occurs in warm humid areas
like rainforests.
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What decreases Biodiversity?

• The two big ones are
• Habitat Loss
• Introduction of new species

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Loss of Habitat

• As humans take up more and more land, there is
  less wilderness available for organisms and many
  risk going extinct.
• Habitat fragmentation occurs when a barrier forms
  that prevents an organism from accessing its home
  range.

Wildlife crossing to prevent fragmentation.
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Introduced Species

• An introduced species is any organism that was
  brought to an ecosystem as a result of human
  actions.
• If an environment has a niche that the introduced
  species can exploit, or if the introduced species
  is a better competitor, original species may be
  pushed out or die. This particularly happens when
  there are no predators for the introduced
  species.
• When an introduced species has established itself
  in a new ecosystem, it is called an invasive
  species.

Burmese Python
Nile Perch
Kudzu
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Conservation

• Sustainable development is a practice in which
  natural resources are used and managed in a way
  that meets current needs without hurting future
  generations.
• Example Global Fisheries
• Overfishing has depleted fish populations
  worldwide. Fish stocks are not as hardy as they
  once were. One reason for this, is the fish that
  are caught represent the healthy, reproducing age
  groups of the fish population.

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Making Fisheries Sustainable
Bottom-Trawling

• Rotation rotating catches between different
  species gives the off species time to recover
  their numbers.
• Fishing Gear Review choosing gear that doesnt
  hurt the sea floor or unintentionally catch other
  species.
• Harvest Reduction Slowing the harvests of
  deep-water species that grow very slowly allows
  more time for them to recover.
• Fishing Bans Creating and enforcing bans in
  certain areas and on certain species helps to
  replenish numerous populations in the area.

Bottom-Trawling catch
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Which species do we save?

• Conservationists try to focus efforts on umbrella
  species, which are species whose being protected
  leads to preservation of its habitat and all the
  other organisms in its community.

Manatee
Bay Checkerspot Butterfly
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• What density-independent and density-dependent
  limiting factors may prevent the human population
  from continued growth?
• What are 3 factors that determine how big your
  footprint will be?
• Whats the difference between renewable and
  non-renewable resources? Give an example for each
  and explain why they are renewable or
  non-renewable.
• Where does the energy burned off in coal or oil
  originally come from?
• How does the greenhouse effect keep Earth warm?
• How could the build-up of CO2 in the atmosphere
  increase Earths global temp?
• What contributes to the formation of ground level
  ozone and smog?
• Describe how acid rain falling in a forest could
  disrupt the trophic structure of the ecosystem.
• How are the concepts of carrying capacity and
  indicator species related?
• Are humans likely affected by biomagnification?
  If so, what foods might be dangerous?
• Give two reasons why biodiversity is important to
  humans.
• How might the introduction of a predator to an
  invasive species cause more problems?
• Give 2 examples of sustainable development.
• In terms of conservation, why focus on umbrella
  species?