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ENVSCI 101

The Global Environment

Midterm Exam 1 Part B

Spring, 2022

Exam Front Page Instructions:

The following exam will test your ability to recall basic concepts and definitions as well as integrate the body of knowledge that you have accumulated during the first part of the semester.

The exam will consist of two (2) sections. SECTION A has 6 short answer questions. It will be worth 5 points each. These will be 4-5 sentence answers (about 50 words) or diagrams where necessary. SECTION B has 1 long essay question. These will be about a page long detailed answers (100 -150 words). It will be worth 20 points. Word limit is just an approximation for the answers. As long as the answer satisfies the question asked, you are good to go.

You have between (Feb 22nd- Feb 26th 11:30 pm) to complete the exam. Please feel free to ask questions if you do not understand any aspect of the exam. You can submit your answers as a word document or a pdf in the allotted folder by the due date. If you are using information from the web, mention their sources.

Section A: Short Answer and Diagrams (30 points):

Answer the following questions to the best of your ability. Be sure to provide specific details when answering questions and drawing diagrams.

1. What are five things you would do to cut waste in human societies by following principle of sustainability?

2. How can the extinction of bird species create a ripple effect through the rest of the ecosystem?

3. Use the second law of thermodynamics to explain why we cannot recycle the high-quality chemical energy stored in gasoline.

4. If anthropogenic processes introduce increasing amounts of atmospheric nitrogen to the biosphere and hydrosphere, where does that nitrogen go?

5. What can city planners do to make residents less dependent on cars, apart from providing public transit options?

6. How is it possible that countries with the same population size and affluence could differ in their environmental impacts?

Section B: Long Essay Question (20 points):

Be sure to be specific and provide details for your essay.

1. The “biological capacity” is the ability of the natural world to replenish its renewable resources and absorb the resulting waste products and pollution. Exceeding the biological capacity creates an “ecological deficit.” Discuss the potential future implications for the earth resulting from the fact that we are currently exceeding the earth’s biological capacity by about 50 percent.

The Environment and Sustainability

What is an Environment?

u Biotic factors
u (e.g. plants, animals, farms,

forests)
u Abiotic factors
u (include sunlight, air, water,

earth)
u Four spheres- life support

systems

Environmental Science
u Environmental science studies

connections in nature
u How the earth works and has survived and

thrived
u How humans interact with the environment
u How we can live more sustainably

u Ecology
u Branch of biology focusing on interaction of

living things with their environment
u Ecosystem

Three Scientific Principles of
Sustainability

u Dependence on solar energy

u Biodiversity

u Chemical (nutrient) cycling

Key Components of Sustainability

u Natural capital keeps humans and other species alive
and supports economies

u Natural resources: useful materials and energy in nature
u May be inexhaustible, renewable, or nonrenewable

(exhaustible)
u Ecosystem services

u Processes provided by healthy ecosystems

Key Components of Sustainability

u Natural resource examples
u Inexhaustible:

u A resource that never runs out or gets
depleted.

u Renewable:
u A resource that can be used

repeatedly and is replaced naturally.

u Nonrenewable:
u A resource that is not replenished with

the speed at which it is consumed.

Key Components of Sustainability

u Nutrient cycling is a vital
ecosystem service

u Human activities can degrade
natural capital
u Using renewable resources too

fast

u Overloading air, water, and
soil with wastes and pollutants

u Humans must provide solutions
to environmental problems

Three Additional
Principles of
Sustainability
u Full-cost pricing

u Win-win solutions

u A responsibility to future
generations

Countries Differ in Their Resource
Use and Environmental Impact

u More-developed countries
u Industrialized nations with high

average income per person
u 17% of the world’s population
u Use 70% of world’s natural resources

u Less-developed countries
u 83% of the world’s population
u Use about 30% of world’s natural

resources

Humans Protecting the Environment

u Many people have a better quality of life
u Have developed useful materials and products
u Life spans have increased
u Food supply is more abundant
u Exposure to toxic chemicals is more avoidable

u Humans have protected some endangered species and
ecosystems:
u Taken steps to restore cleared lands
u Businesses and governments work toward improving

environmental quality

We Are Living Unsustainably

u Environmental degradation
u Wasting, depleting, and degrading

u Human activities directly affect 83% of
earth’s land surface
u Urban development, crop and

energy production, mining, timber
cutting, and more

u Species are becoming extinct 100
times faster than in prehuman times

Degrading Commonly Shared Renewable
Resources: The Tragedy of the Commons

u Open-access resources
u Atmosphere, ocean and its fishes,

grasslands, forests, streams, and aquifers
u Cumulative effect of many people

exploiting a shared resource can degrade,
exhaust, or ruin it

u Solution: use resource at a rate well below
its sustainable yield
u Mutual agreement, or access regulation

Our Growing Ecological Footprints

u Ecological footprint
u The impact a person or community has on the environment
u Sustainability measure that relates to the Earth’s biocapacity
u The largest components: air pollution, climate change, and

ocean acidification due to burning fossil fuels for energy

u Ecological deficit
u Footprint is larger than biological capacity for replenishment

Our Growing Ecological Footprints

IPAT – Another Environmental Impact Model

u Simple environmental impact model developed in the
1970s

u I = P x A x T
u I = Environmental impact
u P = Population
u A = Affluence
u T = Technology

u Some technologies are beneficial, some harmful

Cultural Changes Can
Increase or Shrink Our
Ecological Footprints

u Humans were hunter gatherers 10,000 years
ago

u Three major cultural events
u Agricultural revolution

u Industrial–medical revolution

u Information–globalization revolution

u Current need for a sustainability revolution

What Causes Environmental
Problems?

u Basic causes of environmental problems
u Population growth
u Unsustainable resource use
u Omission of harmful environmental costs in market

pricing of goods and services
u Increasing isolation from nature
u Competing environmental worldviews

Human Population is Growing at a
Rapid Rate

u Human population has grown
exponentially
u Current population: 7.9 billion

people

u By 2050, population could reach 9.8
billion

u We don’t know how many people
the earth can support indefinitely

Affluence and Unstainable
Resource Use

u Affluence results in increased resource consumption per
person
u Increases environmental degradation, wastes, and

pollution
u Positive aspects of affluence

u Better and widespread education
uIncreased awareness of environmental issues

u Money available to develop technologies with
beneficial environmental impacts

Exclusion of Harmful Environmental and
Health Costs

u Companies do not pay the environmental cost of
resource use

u Goods and services do not include the harmful
environmental costs
u Consumers lack information

u Companies receive tax breaks and subsidies
u Some subsidies encourage depletion of natural

capital

Isolation from Nature

u Increasing populations in urban areas
u Lack of contact with nature

u Benefits of outdoor activities
u Better health
u Reduced stress
u Improved mental capabilities
u Increased imagination and creativity
u Sense of connection with the earth

Differing Environmental Views

Environmental worldview
Set of assumptions and values

Environmental ethics
Why should we care about the

environment?
Do we have an obligation to protect

other species against extinction caused
by human actions?

Should every person be entitled to equal
protection from environmental hazards?

Differing Environmental Views

Human-centered
environmental

worldview
Life-centered Earth-centered

What Is an
Environmentally
Sustainable Society?

u Living sustainably
u Live off the Earth’s

natural income
without depleting
or degrading the
natural capital that
supplies it

We Can Live More Sustainably

Learn from nature Protect natural capital
Do not waste
resources

Recycle and reuse
nonrenewable
resources

Use renewable
resources at a rate
slower than nature
can replenish them

We Can Live More Sustainably

INCORPORATE HARMFUL HEALTH
AND ENVIRONMENTAL IMPACTS IN

MARKET PRICES

PREVENT FUTURE ECOLOGICAL
DAMAGE AND REPAIR PAST

DAMAGE

FIND WIN–WIN SOLUTIONS TO
ENVIRONMENTAL PROBLEMS

ACCEPT RESPONSIBILITY TO PASS
THE EARTH ON TO FUTURE

GENERATIONS IN A CONDITION AS
GOOD AS OR BETTER THAN WHAT

WE INHERITED

  • �The Environment and Sustainability�
  • What is an Environment?
  • Environmental Science
  • Three Scientific Principles of Sustainability
  • Key Components of Sustainability
  • Key Components of Sustainability
  • Key Components of Sustainability
  • Three Additional Principles of Sustainability
  • Countries Differ in Their Resource Use and Environmental Impact
  • Humans Protecting the Environment
  • We Are Living Unsustainably
  • Degrading Commonly Shared Renewable Resources: The Tragedy of the Commons
  • Our Growing Ecological Footprints
  • Slide Number 14
  • IPAT – Another Environmental Impact Model
  • Cultural Changes Can Increase or Shrink Our Ecological Footprints
  • What Causes Environmental Problems?
  • Human Population is Growing at a Rapid Rate
  • Affluence and Unstainable Resource Use
  • Exclusion of Harmful Environmental and Health Costs
  • Isolation from Nature
  • Differing Environmental Views
  • Differing Environmental Views
  • What Is an Environmentally Sustainable Society?
  • We Can Live More Sustainably
  • We Can Live More Sustainably

SCIENCE, MATTER, ENERGY, AND
SYSTEMS

WHAT IS SCIENCE?

Science is:
• A field of study focused on discovering how nature works

– happens at a variety of scales
• Using that knowledge to describe what is likely to happen

in nature
• Based on the assumption that events in the natural world

follow orderly cause-and-effect patterns
• Patterns can be understood through observations (by use

of our senses and with instruments that expand our
senses), measurements, and experimentation

SCIENTISTS:

• Identify a problem for study
• Gather relevant data
• Propose a hypothesis that explains the

data

• Gather data to test the hypothesis
• Modify the hypothesis as needed

The process is known as the scientific method

HYPOTHESES

What is a “hypothesis”?
• A “hypothesis” is an idea or explanation that is tested through study and

experimentation.

• Examples:
• Problem: The amount of light in the room effects test scores of the students.

Hypothesis: If we increase the amount of light during studying, student’s performance on test
scores will decrease.

• Problem: Too many deer found in residential areas.
Hypothesis: Deer prefer to stay closer to human settlements.

SCIENTISTS

• Scientists modify, or revise, the hypothesis as needed.
• Scientists share their results

SCIENTIFIC THEORIES AND LAWS: THE MOST
IMPORTANT AND CERTAIN RESULTS OF SCIENCE

• Scientific theory
• Widely tested and supported by evidence

• Scientific law or law of nature
• Well-tested, widely accepted description of what happens repeatedly

and in the same way in nature

WHAT IS MATTER?

• Matter is anything that has mass* and takes
up space.

• It exists in three physical states – solid, liquid, and
gas.

• *Mass=the constant amount of matter/material in
something. Often measured in g or kg. (NOT the
same as weight, which depends on gravity)

• Exists in three physical states: solid, liquid, or gas

MATTER CONSISTS OF ELEMENTS AND
COMPOUNDS

• Two chemical forms: elements and
compounds

• Elements
• Have unique properties
• Cannot be broken down chemically

into other substances

• Known elements arranged in a chart called
periodic table of the elements

MATTER CONSISTS OF ELEMENTS AND
COMPOUNDS

• Most matter consists of Compounds
• Two or more different elements held together in fixed proportions
• Example = H20 (hydrogen and oxygen)

ELEMENTS AND COMPOUNDS ARE MADE OF
ATOMS, MOLECULES, AND IONS

• Atomic theory
• All elements are made of atoms
• Atom is the smallest unit of matter into which an element can be divided

and still have distinct chemical properties
• Subatomic particles

• Nucleus of the atom
• Protons have positive charge
• Neutrons have no charge

• Negatively charged electrons orbit the nucleus

ELEMENTS AND COMPOUNDS ARE MADE OF
ATOMS, MOLECULES, AND IONS

• Each element has a unique atomic number
• Same as number of protons in nucleus
• Example: Carbon (C): 6 protons in its nucleus and an atomic

number of 6

• Example: Uranium (U): 92 protons, atomic number of 92
• Most of an atom’s mass is in its nucleus
• Electrons have very little mass compared to protons and

neutrons

ELEMENTS AND COMPOUNDS ARE MADE OF
ATOMS, MOLECULES, AND IONS

• Mass number
• Number of protons plus neutrons in nucleus
• Example: Carbon atom has 6 protons and 6 neutrons in its nucleus – its mass

number is 12.
• Example: Uranium atom has 92 protons and 143 neutrons – its mass number

of 235.

• Isotope
• Form of an element with same atomic number but different mass number

• Each atom of an element has the same number of protons in its nucleus
• The number of neutrons in an element’s nucleus can change
• Therefore, the mass numbers can also change

ELEMENTS AND COMPOUNDS ARE MADE OF
ATOMS, MOLECULES, AND IONS

• Molecule
• Combination of two or more atoms of same or

different elements

• Held together by chemical bonds
• Molecules are basic building blocks of many

compounds.

• Examples – water, hydrogen gas, and methane

ELEMENTS AND COMPOUNDS ARE MADE OF ATOMS,
MOLECULES, AND IONS

• Ions
• An atom or a group of atoms (a molecule) with

one or more net positive (+) or negative (−)
electrical charges from losing or gaining
negatively charged electrons

• Ions are attracted to other ions with opposite
electronic charges (+ to -, and – to +), which
leads to ionic bonding and the creation of ionic
compounds.

• Example: salt (sodium (Na+) chloride (Cl-))

ELEMENTS AND COMPOUNDS ARE MADE OF
ATOMS, MOLECULES, AND IONS

• Acidity
• Measure of comparative amounts of hydrogen ions (H+) and hydroxide

ions (OH–) in a volume of water solution

• Measured with pH
• Neutral solution has pH equal to 7
• Acidic solution has pH < 7 (more hydrogen ions than hydroxide ions)
• Basic solution has pH > 7 (more hydroxide ions than hydrogen ions)

ORGANIC COMPOUNDS ARE THE
CHEMICALS OF LIFE

• Organic compounds
• Contain at least two carbon atoms

• Exception: methane (CH4)
• Types

• Hydrocarbons
• Simple carbohydrates

• Macromolecules: complex organic molecules
• Complex carbohydrates, proteins, nucleic acids,

and lipids

MATTER COMES TO LIFE
THROUGH CELLS, GENES,
AND CHROMOSOMES
• Cells

• Fundamental units of life
• All organisms have one or more cells

• Genes
• Sequences of nucleotides within DNA
• Instructions called genetic information
• Create inheritable traits

• Chromosomes: composed of many genes

MATTER CAN CHANGE

• Physical change
– No change in chemical composition
– Example: crushing a bottle,

chopping wood, and melting ice

• Chemical change
– Change in chemical composition
– Example: Carbon dioxide

LAW OF CONSERVATION OF MATTER

• We can change elements and compounds from one physical or chemical form
to another

• We cannot create or destroy atoms

WHAT IS ENERGY AND WHAT ARE ITS FORMS

• Energy: ability to do work
• Kinetic energy

• Energy of movement
• Electromagnetic radiation
• Thermal energy

• Potential energy

ENERGY COMES IN MANY FORMS

• Kinetic energy is matter in motion.
• Energy of movement

• Examples: running water, a ball rolling down a hill, electrons flowing through a wire
(electricity), light, and a mass of air moving (wind)

ENERGY COMES IN MANY FORMS

• Kinetic energy is matter in motion.
• Electromagnetic radiation is energy that travels in the form of

waves.
• Example: visible light and the spectrum of electromagnetic radiation

from the sun

• Light is made of photons which are produced when atoms heat
up.

• Light travels in waves
• Light is the only form of energy visible to the human eye.

ENERGY COMES IN MANY FORMS

• Kinetic energy is matter in motion.
• Heat/Thermal energy is the total kinetic energy of all moving atoms, ions, or molecules in

an object, a body of water, or a volume of gas such as the atmosphere.

• If the atoms, ions, or molecules in a sample of matter move faster, the matter will
become warmer.

• When two objects at different temperatures make contact with each another, heat
flows from the warmer object to the cooler object.

• Heat is transferred through radiation, conduction, and convection.

ENERGY COMES IN MANY FORMS

• Radiation is the transfer of heat energy through space by
electromagnetic radiation in the form of infrared radiation.

• Heat from the sun reaches the earth
• Heat from a fireplace transfers to the surrounding air

• Conduction is the transfer of heat from one solid substance
to a cooler one when they are in physical contact. Energy
moves from hot to cold.

• Touching a hot object
• Electric stove burner heats a pan

• Convection is the transfer of heat energy within liquids
or gases when warmer areas of the liquid or gas rise to
cooler areas and cooler liquid or gas takes its place.

ENERGY COMES IN MANY FORMS

• Potential energy
• Stored energy is potentially available for use.
• Examples: a spring, carbon in coal, and water behind a dam
• Can be changed into kinetic energy

WHAT IS ENERGY AND WHAT HAPPENS WHEN IT
UNDERGOES CHANGE?

• Whenever energy is converted from one form to another in a physical or chemical
change:

• No energy is created or destroyed when converted from one form to another (first law of
thermodynamics/Law of Conservation of Energy)

• You end up with lower quality or less-usable energy than you started with (second law of
thermodynamics)

• Lower quality energy is usually in the form of heat flowing into the environment.
• The temperature drops to the point that quality is too low to do much useful work.

ENERGY CHANGES OBEY TWO SCIENTIFIC LAWS

• Energy efficiency
• Measure of how much work results from a unit of

energy put into a system

• Improving efficiency reduces waste
• Estimate: 84% of energy used in the U.S. is wasted

• Unavoidably because of second law of
thermodynamics (41%)

• Unnecessarily (43%)

ENERGY IS RENEWABLE AND NONRENEWABLE

• Renewable energy
• Gained from resources that are replenished

by natural processes in a relatively short time

• Nonrenewable energy
• Gained from resources that can be depleted

and are not replenished by natural processes
within human time scale

ENERGY IS RENEWABLE AND NONRENEWABLE

• Solar energy
• 99% of the energy that keeps us warm and supports plants and other organisms

• Commercial energy
• Energy sold in the marketplace
• Supplements sun’s energy
• 90% comes from burning fossil fuels

• Oil, coal, and natural gas

WHAT ARE SYSTEMS AND
HOW DO THEY RESPOND
TO CHANGE?

• System
• Set of components that interact in a regular way
• Examples: human body, a cell, a TV set, and an

economy

• Systems have inputs, flows, and outputs of matter,
energy, and information

• Feedback can affect their behavior

SYSTEMS AND
FEEDBACK LOOPS

• Feedback
• Any process that increases or decreases a

change to a system

• Positive feedback loop
• Causes system to change further in the

same direction (can lead to tipping point).
• Example: Decreasing vegetation in a

valley causes increasing erosion and
nutrient losses that in turn cause more
vegetation to die, resulting in more erosion
and nutrient losses.

SYSTEMS AND FEEDBACK LOOPS

• Negative, or corrective, feedback loop
• Causes system to change in opposite

directions
• Example: Air conditioner goes on until a

specific temperature is reached and then
goes off and the house starts to warm until it
reaches a specified temperature and turns the
air conditioner on

SYSTEMS AND FEEDBACK LOOPS

• Most systems in nature use negative feedback to enhance long-term stability.
• Ecological tipping point

• Natural system stuck in positive feedback loop can reach this point
• Beyond this point, system changes so drastically it suffers from severe

degradation or collapse

  • �Science, Matter, Energy, and Systems�
  • What Is Science?
  • ScientiSTS:
  • Hypotheses
  • Scientists
  • Scientific Theories and Laws: The Most Important and Certain Results of Science
  • What Is Matter?
  • Matter Consists of Elements and Compounds
  • Matter Consists of Elements and Compounds
  • Elements and Compounds Are Made of Atoms, Molecules, and Ions
  • Elements and Compounds Are Made of Atoms, Molecules, and Ions
  • Elements and Compounds Are Made of Atoms, Molecules, and Ions
  • Elements and Compounds Are Made of Atoms, Molecules, and Ions
  • Elements and Compounds Are Made of Atoms, Molecules, and Ions
  • Elements and Compounds Are Made of Atoms, Molecules, and Ions
  • Organic Compounds Are the �Chemicals of Life
  • Matter Comes to Life through Cells, Genes, and Chromosomes
  • Matter Can Change
  • Law of Conservation of Matter
  • What is Energy and What are its Forms
  • Energy comes in many forms
  • Energy comes in many forms
  • Energy comes in many forms
  • Energy Comes in Many Forms
  • Energy Comes in Many Forms
  • What is Energy and What Happens When It Undergoes Change?
  • Energy Changes Obey Two Scientific Laws
  • Energy Is Renewable and Nonrenewable
  • Energy Is Renewable and Nonrenewable
  • What Are Systems and How Do They Respond to Change?
  • Systems and Feedback Loops
  • Systems and Feedback Loops
  • Systems and Feedback Loops

Ecosystems: What Are They and How
Do They Work?

How Does the Earth’s Life-Support
System Work?

u Major components of the earth’s life-support system

u Atmosphere (air)

u Hydrosphere (water)

u Geosphere (rocks, minerals, and soil)

u Biosphere (living things)

Earth’s Life-Support System Has Four
Major Components
u Atmosphere

u Innermost layer is the troposphere

uContains the air we breathe

u Stratosphere: contains ozone layer

uFilters sun’s harmful UV radiation

u Hydrosphere

u All water vapor, liquid water, and ice

u Oceans contain 97% of the planet’s water

Earth’s Life-Support System Has Four
Major Components

u Geosphere

u Upper portion of crust contains nutrients
organisms need to live, grow, and
reproduce

u Contains nonrenewable fossil fuels

u Biosphere

u Parts of atmosphere, hydrosphere, and
geosphere where life is found

Three Factors Sustain the Earth’s Life

u One-way flow of high-quality energy from the sun that
supports plant growth and warms troposphere (greenhouse
effect)

Three Factors Sustain the Earth’s Life

 Cycling of nutrients through parts of the biosphere

 Gravity holds the earth’s atmosphere and enables
movement and cycling of chemicals through air, water,
soil, and organisms

What Are the Major Components
of an Ecosystem?

u Ecologists study five levels of

matter

u Biosphere, ecosystems,

communities, populations,

and organisms

u Ecology assigns each organism to a feeding

level (trophic level)

u Organisms classified as producers or

consumers based on source of nutrients

Ecosystems Have Several
Important Components

u During photosynthesis, plants generate energy
and emit oxygen
u CO2 + H2O + sunlight → glucose + oxygen

u Producers (autotrophs) make needed nutrients
from their environment

u Consumers (heterotrophs) cannot produce the
nutrients they need
u Primary consumers (herbivores) eat plants

u Carnivores feed on flesh of other animals

u Secondary and tertiary (or higher) consumers

u Omnivores eat both plants and animals

Ecosystems Have Several Important
Components

u Decomposers
u Consumers that recycle dead plants and animals into chemical

nutrients like carbon and nitrogen that are released back into the
soil, air and water

u Directly absorb nutrients through external chemical and biological
processes

u Nutrients return to soil, water, and air
for reuse
u Bacteria, fungi and earthworms are big
decomposers
u Detritivores

uIngest and digest dead matter internally

Ecosystems Have Several Important
Components

u Producers, consumers, and
decomposers use chemical
energy stored in glucose
u In most cells, energy is

released by aerobic
respiration

u Using oxygen to turn
glucose back to carbon
dioxide and water

Soil Is the Foundation of Life on Land

u Soil
u Complex mixture of rock, particles, mineral nutrients, organic

matter, water, air, and living organisms

u Soil formation begins with weathering of rock
u Various forms of plant and animal life begin living in the weathered

particles.

u Their waste and decaying bodies add organic matter and minerals
to the slowly forming soil.

u Mature soils contain several layers (horizons)

u Differ in texture, composition, and thickness

Soil Is the Foundation of Life on Land

u Soil is a renewable resource
u Renews very slowly
u Formation of one inch of topsoil

can take hundreds to thousands
of years

u Becomes nonrenewable if it is
depleted faster than it can be
replenished

u Protecting and renewing topsoil
is key to sustainability

Soil Is the Foundation of Life on Land

What Happens to Energy in an
Ecosystem?

u Energy flows through ecosystems in food chains and webs

u Food chain

u Movement of energy and nutrients from one trophic
level to the next

u Food web

u Network of interconnected food chains

What Happens to Energy in an
Ecosystem?

What Happens to Energy in an
Ecosystem?

u Every use and transfer of energy involves energy loss as heat
u Pyramid of energy flow

u 90% of energy lost with each transfer through metabolic
heat: why food chains and webs rarely have more than 4 or 5
trophic levels

u Less chemical energy for higher trophic levels
u About 2/3 of the world’s people survive by eating wheat,

rice, and corn at the first trophic level.
u Biomass

u Total mass of organisms in a given trophic level

What Happens to Energy in an
Ecosystem?

Some Ecosystems Produce Plant Matter
Faster than Others Do
u Gross primary productivity

(GPP)
u Rate at which an ecosystem’s

producers (plants and
phytoplankton) convert solar
energy to stored chemical
energy

u Measured in units such as
kcal/m2/year

Some Ecosystems Produce Plant Matter Faster
than Others Do

u Net primary productivity (NPP)

u Rate at which an ecosystem’s producers
convert solar energy to chemical energy,
minus the rate at which they use the
stored energy for aerobic respiration

u The planet’s NPP ultimately limits the
number of consumers (including humans)
that can survive on the earth

Some Ecosystems Produce Plant Matter
Faster than Others

What Happens to Matter in an
Ecosystem?

u Matter in the form of nutrients cycles within and among
ecosystems

u Cycles driven by incoming solar energy and gravity

u Can be altered by human activity

u Nutrient Cycles

u Water, carbon, nitrogen, and phosphorus

Water Cycle Sustains all Life

u The water cycle collects, purifies, and
distributes the Earth’s fixed supply of
water.

u Renews water quality.
u The sun powers the water cycle.
u Incoming solar energy causes

evaporation.
u Gravity draws water back as

precipitation:
u Surface runoff evaporates to complete the

cycle

u Some precipitation is stored underground
as groundwater

u Some precipitation is converted to ice and
stored in glaciers

Water Cycle Sustains all Life
u Only 0.024% of the Earth’s freshwater supply is available to

humans and other species.

u The ways humans alter the water cycle:

u Withdrawing large amounts of freshwater from aquifers at rates
faster than nature can replace it

u Clearing vegetation (agriculture, road building), which increases
runoff

u Draining and filling wetlands for farming and urban development

Science Focus: Water’s Unique
Properties

u Properties of water
u Liquid over large temperature range

u Changes temperature slowly because it can
store a large amount of heat

u Takes lots of energy to evaporate

u Can dissolve a variety of compounds (also can
make it polluted)

u Filters out wavelengths of UV radiation and
protects aquatic organisms

u Expands when it freezes

Carbon Cycles among
Living and Nonliving
Things

u Carbon is the basic building block of
carbohydrates, fats, proteins, DNA,
and other organic compounds.

u Photosynthesis from producers
removes CO2 from the atmosphere
and aerobic respiration by
producers, consumers, and
decomposers adds CO2 .

u Some CO2 dissolves in the ocean
and is stored in marine sediments.

Human Disruption of the Carbon Cycle

u Humans have added large quantities of CO2 to the atmosphere

u Faster rate than natural processes can remove

u Levels have been increasing sharply since about 1960

u Carbon from fossil fuels are being burned back into atmosphere

u Result is the warming atmosphere and changing climate

u Clearing vegetation reduces ability to

remove excess CO2 from the atmosphere

Nitrogen Cycle: Bacteria in Action

u Nitrogen is a critical nutrient for all forms of life.

u Nitrogen gas makes up 78% of the volume of the atmosphere.

u Useful forms of nitrogen are created in the nitrogen cycle:

u Created by lightning and specialized bacteria in topsoil and
bottom sediment of aquatic systems

u Used by plants to produce proteins, nucleic acids, and vitamins

u Bacteria converts nitrogen compounds back into nitrogen gas.

Nitrogen Cycle: Bacteria in Action

u Human alteration of the nitrogen cycle

u Burning gasoline and other fuels create nitric oxide,
which can return as acid rain

u Removing large amounts of nitrogen from the
atmosphere to make fertilizers

u Adding excess nitrates in aquatic ecosystems

u Human nitrogen inputs to the environment have risen
sharply and are expected to continue rising

Nitrogen Cycle: Bacteria in Action

Phosphorous Cycles through Water, Rock,
and Food Webs

u Phosphorus
u Another nutrient that supports life
u Cycles through water, the Earth’s crust, and living

organisms
u Major reservoir is phosphate rocks
u Cycles slowly
u Does not cycle through the atmosphere because

few of the compounds exist as gas
u Lack of phosphorus limits growth of producer

populations (plants)

Phosphorous Cycles through Water, Rock,
and Food Webs

u Phosphorus

u Human activities and impacts

uClearing forests

uRemoving large amounts of phosphate
from the Earth to make fertilizers

uErosion leaches phosphates into streams

Phosphorous Cycles through Water, Rock, and Food Webs

  • ������Ecosystems: What Are They and How Do They Work?�
  • How Does the Earth’s Life-Support System Work?
  • Earth’s Life-Support System Has Four�Major Components
  • Earth’s Life-Support System Has Four�Major Components
  • Three Factors Sustain the Earth’s Life
  • Three Factors Sustain the Earth’s Life
  • What Are the Major Components of an Ecosystem?
  • Ecosystems Have Several Important Components
  • Ecosystems Have Several Important Components
  • Ecosystems Have Several Important Components
  • Soil Is the Foundation of Life on Land
  • Soil Is the Foundation of Life on Land
  • Soil Is the Foundation of Life on Land
  • What Happens to Energy in an Ecosystem?
  • What Happens to Energy in an Ecosystem?
  • What Happens to Energy in an Ecosystem?
  • What Happens to Energy in an Ecosystem?
  • Slide Number 18
  • Some Ecosystems Produce Plant Matter Faster than Others Do
  • Some Ecosystems Produce Plant Matter Faster than Others Do
  • Some Ecosystems Produce Plant Matter Faster than Others
  • What Happens to Matter in an Ecosystem?
  • Water Cycle Sustains all Life
  • Water Cycle Sustains all Life
  • Science Focus: Water’s Unique Properties
  • Carbon Cycles among Living and Nonliving Things
  • Human Disruption of the Carbon Cycle
  • Nitrogen Cycle: Bacteria in Action
  • Nitrogen Cycle: Bacteria in Action
  • Nitrogen Cycle: Bacteria in Action
  • Phosphorous Cycles through Water, Rock, and Food Webs
  • Phosphorous Cycles through Water, Rock, and Food Webs
  • Phosphorous Cycles through Water, Rock, and Food Webs

Biodiversity

Lecture 4

What Are the Major Types of Life on the
Earth?

• Every organism is composed of one or more
cells.

• Cell:
• Known as the “building blocks of life”
• Surrounded by a structure called the cell membrane

What Are the Major Types of Life on the
Earth?

• Classification based on cell structure
• Prokaryotic (bacterial cells)

• Cells enclosed by a membrane but containing no distinct nucleus or other internal parts
enclosed by membranes

• Eukaryotic
• All nonbacterial organisms

• Cells are encased in a membrane and have a distinct nucleus (a membrane-bounded
structure containing genetic material in the form of DNA) and several other internal parts
enclosed by membranes.

What Are the Major Types of Life on the
Earth?

Taxonomies

Scientists group organisms into
categories based on their greatly
varying characteristics.
• Taxonomic classification:

• Domain, kingdom, phylum, class,
family, genus, and species

Kingdoms

• Archaebacteria
• Eubacteria
• Protista (algae and protozoans)
• Plantae: Plants (mosses, ferns, and

flowering plants)
• Fungi (mushrooms, molds, mildew,

and yeasts)
• Animalia: Animals (invertebrates

and vertebrates)

Taxonomies video

• https://www.youtube.com/watch?v=kKwOlAqQoLk

Earth’s Organisms Are Many and Varied

• Species – group of organisms with characteristics that
distinguish it from other groups of organisms.

• Estimated 7–10 million species exist
• About 2 million species have been identified

• About half of those are insects

• Pollination is a vital ecosystem service performed by insects
• Biological control

What Is Biodiversity and Why Is It Important?

• Biological diversity is the diversity of life on earth
• Four components:
• Species diversity

• Includes species richness (the number of different species) and evenness
(comparative abundance of all species)

• Genetic diversity
• Variety of genes in a population or species

• Ecosystem diversity
• Biomes: regions with distinct climates and species

• Functional diversity
• Biological and chemical processes, such as energy flow and matter recycling, needed

for the survival of species, communities, and ecosystems

What is Biodiversity?

• https://www.youtube.com/watch?v=b6Ua_zWDH6U

Species Diversity

• Species diversity includes species richness (number of different species) and
evenness (comparative abundance of all species).

• If an ecosystem only has three species, its richness is low. But if there are an
equal number of each of the three species, the species evenness is high.

• Species richness is highest in the tropics and declines as we move toward the
poles.

• Most species rich environments are tropical rain forests, large tropical lakes,
coral reefs, and the ocean-bottom zone.

Species Diversity

Functional Diversity

Functional diversity is the biological and chemical processes, such
as energy flow and matter recycling, needed for the survival of
species, communities, and ecosystems.

-What is/are the organism(s) doing?
-How does it interact with other organisms and the environment

Genetic Diversity

• Variety of genes in a population or species
• Genes contain genetic information that give rise to specific traits, or

characteristics, that are passed on to offspring through reproduction.
• Species have a better chance of surviving and adapting to environmental changes

if they have greater genetic diversity.

Ecosystem Diversity

• Biomes: Regions with distinct climates and species
(terrestrial classification)

• tropical rainforests, temperate forests, deserts, tundra,
boreal forests, grasslands, and savanna

• Biomes differ in their community structure based on the
types, relative sizes, and stratification of their plant species

Major Biomes across United States

Ecosystem Diversity

• Large areas of forest and other biomes have a core habitat and edge habitats
with different environmental conditions and species, called edge effects

• Natural ecosystems within biomes rarely have distinct boundaries.
• Instead, one ecosystem tends to merge with the next in a transitional zone

called an ecotone
• Ecotone: a region containing a mixture of species from adjacent ecosystems along with

some migrant species not found in either of the bordering ecosystems

• Humans have fragmented many biomes into isolated patches with less core
habitat and more edge habitat that supports fewer species.

What Role Do Species Play in Ecosystems?

• Each species plays a specific ecological role called its niche
• Includes everything that affects survival and reproduction

• Water, space, sunlight, food, and temperatures
• What it eats
• How much water it drinks
• When it reproduces
• Niche is NOT the same as habitat, which is where a species lives
• Related to functional diversity component of biodiversity

What Role Do Species Play in Ecosystems?

• Niches are used to classify species into 2
categories:

• Generalist species
• Broad niche—wide range of tolerance

• Specialist species
• Narrow niche—narrow range of tolerance

Niches

• Further classification of niches depends on
the roles that species play in ecosystems:

• Native species normally live and thrive in a
particular ecosystem

• Nonnative species migrate or are accidentally
introduced into an ecosystem

Invasive Species

• https://www.youtube.com/watch?v=spTWwqVP_2s

Niches

• Further classification of niches depends on the
roles that species play in ecosystems:

• Indicator species provide early warnings of
environmental changes

• Lichens, Trout

Niches

• Further classification of niches depends on the roles that species
play in ecosystems:

• Keystone species have a large effect on the types and abundance of
other species (such as pollination and population regulation)

• E.g., Saguaro cactus – habitat, food
• Species can play one or more roles in an ecosystem

• https://www.youtube.com/watch?v=JGcIp4YEKrc

  • �Biodiversity�
  • What Are the Major Types of Life on the Earth?
  • What Are the Major Types of Life on the Earth?
  • What Are the Major Types of Life on the Earth?
  • Taxonomies
  • Kingdoms
  • Slide Number 7
  • Taxonomies video
  • Earth’s Organisms Are Many and Varied �
  • What Is Biodiversity and Why Is It Important?
  • What is Biodiversity?
  • Species Diversity
  • Species Diversity
  • Functional Diversity
  • Genetic Diversity
  • Ecosystem Diversity
  • Major Biomes across United States
  • Ecosystem Diversity
  • What Role Do Species Play in Ecosystems?
  • What Role Do Species Play in Ecosystems?
  • Niches
  • Invasive Species
  • Niches
  • Niches

Evolution
Lecture 5

How Does the Earth’s Life Change over Time?

• Biological evolution
• The process by which Earth’s life forms change

genetically over time
• Helps explain why there is such biodiversity
• Widely accepted scientific theory

• Natural selection
• Process by which species have evolved from earlier

species

Evolution Explains How Organisms Change
over Time

• Fossils
• Physical evidence of past organisms
• Preserved in rocks or ice

• Fossil record
• Entire body of fossil evidence
• Uneven and incomplete

• Estimate: fossils found so far represent only
1% of all species that have ever lived

Evolution Depends on Genetic Variability and
Natural Selection

• Darwin and Wallace independently proposed the concept of
natural selection in 1850s.

• Biological evolution involves changes in a population’s genetic
makeup over generations.

• Populations, not individuals, evolve.

Steps of Evolution

1. Genetic variability
2. Natural Selection

Genetic Variability

• First step in evolution: Genetic variability
• Occurs through mutations

• Random changes in DNA as cells divide and DNA is copied
• Can be the result of exposure to external factors (like

chemicals and radioactivity)
• Some mutations can be beneficial, and others can be

harmful
• Some can result in heritable traits

Natural Selection

• Natural selection
• Environmental conditions favor increased survival and reproduction

of certain individuals in a population
• Survival of the fittest

Natural Selection

• Adaptive trait
• Improves the ability of an individual organism to survive and

reproduce at a higher rate than other individuals in a population
• Given prevailing environmental conditions

Evolution Depends on Genetic Variability and
Natural Selection

• Genetic resistance
• Example of natural selection at work
• Occurs when organisms have genes that can tolerate a chemical designed to kill them
• Resistant individuals survive and reproduce

• Some disease-causing bacteria have developed resistance to
antibacterial drugs (antibiotics)

Evolution Depends on Genetic Variability and
Natural Selection

• Human species adaptations
• Strong opposable thumbs
• Ability to walk upright
• A complex brain

Limits to Adaptation through Natural
Selection

• Adaptive genetic traits must precede change in the environmental
conditions

• A population’s reproductive capacity
• Species that reproduce rapidly and in large numbers are better able

to adapt

Myths about Evolution through Natural
Selection

• Five common myths
• Survival of the fittest means survival of the strongest.
• Evolution explains the origin of life.
• Humans evolved from apes or monkeys.
• Evolution is part of nature’s grand plan to produce perfectly adapted

species.
• Evolution by natural selection is not important because it is just a theory.

How do New Species Arise?

• New species arise in two
phases

• Geographic isolation
• Reproductive isolation

What Factors Affect Biodiversity?

• New species arise in two phases
• Geographic isolation

• Occurs first
• Populations migrate or are separated

by some other cause

What Factors Affect Biodiversity?

• Reproductive isolation
• Mutation and change by natural

selection occurs in the geographically
isolated groups

• Eventually prevents breeding between
the groups

What Factors Affect Biodiversity?

Geological Processes Affect Biodiversity

• Tectonic plates affect evolution and the
distribution of life on earth

• Locations of continents and oceans have shifted
through geologic time

• Species move and adapt to new environments,
allowing speciation

• Earthquakes can separate and isolate
populations

• Volcanic eruptions can destroy habitats

Artificial Selection and Genetic Engineering

• Artificial selection
• Selective breeding (or crossbreeding)
• Occurs between genetically similar species
• Not a form of speciation
• Slow process

• Genetic engineering
• Way to speed process of artificial selection
• Gene splicing

Extinction

• Extinction
• Process in which an entire species ceases to exist

• Endemic species
• Found only in one area
• Particularly vulnerable to extinction

• Background extinction
• Typical low rate of extinction

• 0.0001% of all species per year

Extinction Eliminates Species

• Mass extinction
• Significant rise above background level
• 20–95% of species are eliminated
• Causes unknown but could include:

• Giant volcanic eruptions
• Collisions with meteors or asteroids

• Provides opportunity for evolution of new
species

• Five mass extinctions

Video

• https://www.youtube.com/watch?v=GShGxrw4xOU&feature=emb_
title

  • Evolution
  • How Does the Earth’s Life Change over Time?
  • Evolution Explains How Organisms Change over Time
  • Evolution Depends on Genetic Variability and Natural Selection
  • Steps of Evolution
  • Genetic Variability
  • Natural Selection
  • Natural Selection
  • Evolution Depends on Genetic Variability and Natural Selection
  • Evolution Depends on Genetic Variability and Natural Selection
  • Limits to Adaptation through Natural Selection
  • Myths about Evolution through Natural Selection
  • How do New Species Arise?
  • What Factors Affect Biodiversity?
  • What Factors Affect Biodiversity?
  • What Factors Affect Biodiversity?
  • Geological Processes Affect Biodiversity
  • Artificial Selection and Genetic Engineering
  • Extinction
  • Extinction Eliminates Species
  • Video

Species Interactions,
Ecological Succession,

and Population Control

Lecture 6

How Do Species Interact?

• Five types of species interactions
affect resource use and species
population sizes in an ecosystem

• Competition
• Predation
• Parasitism
• Mutualism
• Commensalism

Competition for Resources

• Most common interaction is
competition

• Interspecific competition
• Competition between

different species to use the
same limited resources

• Resource Partitioning
• Intraspecific competition

Predation

• Predator feeds directly on all or part of a member of another
species (prey)

• Strong effect on population sizes and other factors in ecosystems

• Methods of predation
• Walk, swim, or fly
• Camouflage
• Chemical warfare

• Coevolution

Parasitism, Mutualism, and Commensalism

• Parasitism
• One species (parasite) lives on another organism
• Parasites harm but rarely kill the host
• Examples: tapeworms, sea lampreys, fleas, and ticks

• Mutualism
• Interaction that benefits both species
• Nutrition and protective relationship
• Not cooperation—mutual exploitation
• Example: clownfish live within sea anemones

• Gain protection and feed on waste matter left by
anemones’ meals

• Clownfish protect anemones from some predators
and parasites

Parasitism, Mutualism, and Commensalism

• Commensalism
• Benefits one species and has little effect on the other
• Examples:

• Epiphytes (air plants) attach themselves to trees (Pitcher Plant)
• Birds nest in trees

• https://www.youtube.com/watch?v=doB6fyzoO68

How Do Communities and Ecosystems Respond to
Changing Environmental Conditions?

• Ecological succession
• Normally gradual change in structure and species

composition in a given system

• Primary ecological succession
• Involves gradual establishment of communities of

different species in lifeless areas
• Need to build up fertile soil or aquatic sediments to

support plant community
• Takes hundreds to thousands of years
• Pioneer species such as lichens or mosses quickly spread

and release acids

Ecological Succession Creates and Changes
Ecosystems

• Secondary ecological succession
• Series of terrestrial communities or ecosystems develop in places with soil

or sediment
• Examples: abandoned farmland, burned or cut forests, and flooded land

Ecological succession is an important ecosystem service enriching biodiversity

What Limits the Growth of Populations?

• Population
• Group of interbreeding individuals of the same species

• Population size
• May increase, decrease, or remain the same in response to

changing environmental conditions
• Scientists use sampling techniques to estimate

What Limits the Growth of Populations?

• Population distribution varies over their habitats
• Most populations live together in clumps or groups

• Organisms cluster for resources
• Protection from predators

• Variables that govern changes in population size
• Births, deaths, immigration, and emigration

Several Factors Can Limit Population
Size

• Each population has a range of tolerance
• Variation in physical and chemical

environment under which it can survive

• Limiting factors
• Precipitation (on land)
• Water temperature, depth, clarity, and

other factors (in aquatic environments)

• Population density
• Density-dependent factors (parasites and

diseases spread easily, higher death rates;
finding mates in sexually reproducing
individuals is easy)

No Population Can Grow Indefinitely:
J-Curves and S-Curves

• Some species can reproduce
exponentially

• Reproduce at an early age
• Have many offspring each time they

reproduce
• Short intervals in between

reproductive cycles
• Produces J-shaped curve of growth
• Examples: bacteria and many insect

species

No Population Can Grow Indefinitely:
J-Curves and S-Curves

• Population growth in nature always limited
• Environmental resistance

• Sum of all factors that limit population growth

• Carrying capacity
• Maximum population of a given species that a particular habitat can sustain

indefinitely
• Overshoot results in population crash

No Population Can Grow Indefinitely:
J-Curves and S-Curves

Reproductive Patterns

• r-Selected species
• Species with capacity for a high rate

of population growth
• Examples: algae, bacteria, frogs,

most insects, and many fish
• May go through irregular and

unstable cycles in population sizes

Reproductive Patterns

• K-Selected species
• Species that reproduce later in life
• Have few offspring
• Have long life spans
• Examples: large mammals, whales,

humans, birds of prey, and long-lived
plants

• Can be vulnerable to extinction

Species Vary in Their Life Spans

• Survivorship curve
• Shows the percentages of members of population surviving at different ages

• Late loss (K-selected species)
• Early loss (r-selected species)
• Constant loss (many songbirds)

Humans Are Not Exempt from Nature’s
Population Controls

• Ireland
• Potato crop destroyed by fungus in 1845
• Killed one million people

• Bubonic plague
• Killed 25 million during the 14th century in densely populated European

cities

• Technological, social, and cultural changes have expanded earth’s
carrying capacity for the human species today

  • �Species Interactions, Ecological Succession, and Population Control�
  • How Do Species Interact?
  • Competition for Resources
  • Predation
  • Parasitism, Mutualism, and Commensalism
  • Parasitism, Mutualism, and Commensalism
  • How Do Communities and Ecosystems Respond to Changing Environmental Conditions?
  • Ecological Succession Creates and Changes Ecosystems
  • What Limits the Growth of Populations?�
  • What Limits the Growth of Populations?
  • Several Factors Can Limit Population Size�
  • No Population Can Grow Indefinitely: �J-Curves and S-Curves
  • No Population Can Grow Indefinitely: �J-Curves and S-Curves
  • No Population Can Grow Indefinitely: �J-Curves and S-Curves
  • Reproductive Patterns
  • Reproductive Patterns
  • Species Vary in Their Life Spans
  • Humans Are Not Exempt from Nature’s Population Controls

Human Population

Lecture 7

Past and Current
Population
Growth are Very
Different

” Every second, on average, four or five
children are born, somewhere on the
earth. In that same second, one or two
other people die.

” In 2011 the United Nations announced
that we had reached 7 billion people,
having added the most recent billion in
only 12 years. We’re now growing at 1.05
% per year.

Human Populations Grew Slowly Until Recently

Human Population Growth

” Rate of population growth has slowed since 1960 to
1.05%
” World’s population is still growing
” In 2015, 241,000 people were added every day

” Human population growth is unevenly distributed
geographically
” 2% added to more developed countries
” 98% added to less developed countries

” People are moving from rural to urban areas
” In 2018, 55% of the world’s population lived in urban areas,

and it is increasing
” Urban dwellers are living in less developed countries where

resources for dealing with the growing population are
limited

Perspectives on
Population
Growth

As with many topics in environmental
science, people have widely differing
opinions about population and
resources.

Some believe that population growth
is the ultimate cause of poverty and
environmental degradation.

Others argue that poverty,
environmental degradation, and
overpopulation are all merely
symptoms of deeper social and
political factors.

The worldview we choose to
believe will profoundly affect our
approach to population issues.

What is the Carrying Capacity for Humans?

” We are approaching, or may have surpassed, the
earth’s carrying capacity.

” Maximum number of people who could live in
reasonable freedom and comfort indefinitely, without
decreasing the ability of the earth to sustain future
generations

” Joel Cohen, at Rockefeller University reviewed published
estimates of the maximum human population size the
planet can sustain. 300 years of thinking, converged on a
median value of 10 to 12 billion.

” David Pimental states that “By 2100, 12 billion miserable
humans will suffer a difficult life on Earth.”

Many Factors Determine
Population Growth

Demography encompasses vital statistics about
people, such as births, deaths, and where they live,
as well as total population size.

” Population size increases through births and
immigration
” Decreases through deaths and emigration

” Key factor that determines population size
” Average number of children born to women in a

population (total fertility rate)

The Human Population Can Grow, Decline, or Stabilize

” Crude birth rate
” Number of live births per 1,000 people in a population

per year

” Crude death rate
” Number of deaths per 1,000 people in a population per

year

” Population change = (Births + Immigration) – (Deaths
+ Emigration)

Fertility Rates

” Replacement-level fertility rate
” Average number of children a couple

must bear to replace themselves

” Approximately 2.1
”Higher than 2 because some children

die before reaching reproductive
years

Total Fertility Rate is Impacted by Culture

” Total fertility rate (TFR)

” The number of children born to an average
woman in a population during her entire
reproductive life.

” This rate varies due to education, access to
modern health care, and religious practices.

”Between 1955 and 2018, the global TFR
dropped from 5 to 2.4

”To eventually halt population growth, the
global TFR must drop to the fertility
replacement level of 2.1

Predicting
Population
Change

” Human population size in 2050 is estimated to be between
7.8 billion and 10.8 billion people

” Factors influencing the range of estimates

” Reliability of current population estimates

” Assumptions about trends in fertility

” Different organizations who estimate populations use
different methods and data

People Want Children for Many Reasons

” Importance of children as part of the labor
force
” Especially in less developed countries

” Cost of raising and educating children

” Availability of pension systems

” Urbanization

” Educational and employment opportunities for
women

Fertility is Influenced by Culture

” Average age at marriage
” Availability of reliable birth control methods
” Religious beliefs, traditions, and cultural norms

Life Expectancy is Rising Worldwide

” Life span is the oldest age to which a species is known to survive.
”The average age that a newborn infant can expect to attain in any given

society.
” Worldwide, average life expectancy rose from 48 to 72 yrs between 1955

and 2018.
” Infant mortality rate

”Number of babies out of every 1,000 who die before their first birthday
” Poverty is the single most important factor affecting life expectancy.
” Factors that cause high infant mortality:
” Insufficient food, poor nutrition, and infectious disease.

Migration

” The movement of people into and out of
specific geographic areas

” Reasons for migration

” Jobs and economic improvement

” Religious persecution or ethnic conflict

” Political oppression or war

” Environmental refugees

How Does a Population’s Age Structure
Affect Its Growth or Decline?

o Age structure is the number and percentages of males and females in
young, middle, and older age groups in a population.

o It is an important factor in determining how fast a population grows or
declines.

Age Structure

” Age structure categories
” Pre-reproductive (ages 0–14) – too young to have kids

” Reproductive (ages 15–44)

” Post reproductive (ages 45 and older)

” Country with large percentage of people younger than age 15 will experience rapid population
growth

” Global population of seniors expected to triple between 2018 and 2050

” Most future population growth will happen in less developed countries because of youthful age
structure and rapid population rates.

Age Class Histograms

Aging Populations Can Decline Rapidly

” Graying of the world’s population is due to declining
birth rates and medical advances that have
extended life spans.

” As the percentage of people over 65 increases, more
countries will experience population declines.

” Slow population decline is generally manageable.

” Rapid decline leads to economic problems:
” Proportionally fewer young people working

” Labor shortages

” Some countries with rapidly declining populations:
” Japan, Germany, Italy, Bulgaria, Hungary, Romania,

Cuba, and Portugal

How Can We Slow Human Population
Growth?

” There is argument on whether population growth needs to slow:
” Some say environmental degradation can be linked to population growth

” Ways to slow human population growth:
” Reduce poverty through economic development

” Elevate the status of women

” Encourage family planning

Economic Development

” Demographic transition:
” As countries become industrialized and economically developed, poverty declines (this results in

populations that tend to grow more slowly).

” Several countries are experiencing a stabilized or declining population.

” Reducing poverty is key to improving human health and stabilizing the population.

” It takes 4 stages.

Stage I

o Economic and social conditions
change mortality and births.

o Stage I represents the conditions in a
premodern society.

o Malnutrition, illness, accidents and
other hazards keep high death rates
but high birth rates keep population
relatively constant.

Stage II

o Economic development in Stage II
brings better jobs, medical care,
sanitation, and a generally improved
standard of living, and death rates
often fall very rapidly.

o Birth rates may rise at first, with money
and nutrition, people might want more
children. Later, birth rates fall as
people concentrate their resources on
fewer children.

Stage III

o Note that populations grow rapidly
during Stage III when death rates
have already fallen but birth rates
remain high.

o Population may go one or more
rounds of doubling before coming to
balance again.

Stage IV

o Stage IV represents conditions in
developed countries, where the
transition is complete and both birth
rates and death rates are low, often a
third or less than those in the
predevelopment era.

o Most of northern and western Europe
went through a demographic transition
in 19th and early 20th century.

Improving Women’s Lives Helps Reduce Birth
Rates

” Women have fewer children if:
” Educated

” Able to earn an income

” Society does not suppress their rights

” Women:
” Do most of the domestic work and childcare

” Provide unpaid health care

” Have fewer rights and educational opportunities than men

Family Planning Gives Us Choices

” Family planning allows couples to determine the number and spacing
of their children.

” Birth control usually means any method used to reduce births including
celibacy, delayed marriage, contraception, and methods that prevent
embryo implantation and other methods like induced abortions.

Successful Family Planning Programs Often
Require Significant Societal Changes

” Important societal changes to affect population growth include:
” Improved social, educational, and economic status for women.

” Improved status for children.

” Acceptance of calculated choice as a valid element in life in general and in fertility
in particular.

” Social security and political stability that give people the means and the confidence
to plan for the future.

” The knowledge, availability, and use of effective and acceptable means of birth
control.

Fertility Rates by Country

Access the text alternative for these
images

  • Human Population
  • Past and Current Population Growth are Very Different
  • Human Populations Grew Slowly Until Recently
  • Human Population Growth
  • Perspectives on Population Growth
  • What is the Carrying Capacity for Humans?
  • Many Factors Determine Population Growth
  • The Human Population Can Grow, Decline, or Stabilize
  • Fertility Rates
  • Total Fertility Rate is Impacted by Culture
  • Predicting Population Change
  • People Want Children for Many Reasons
  • Fertility is Influenced by Culture
  • Life Expectancy is Rising Worldwide
  • Migration
  • How Does a Population’s Age Structure Affect Its Growth or Decline?
  • Age Structure
  • Age Class Histograms
  • Aging Populations Can Decline Rapidly
  • How Can We Slow Human Population Growth?
  • Economic Development
  • Stage I
  • Stage II
  • Stage III
  • Stage IV
  • Improving Women’s Lives Helps Reduce Birth Rates
  • Family Planning Gives Us Choices
  • Successful Family Planning Programs Often Require Significant Societal Changes
  • Fertility Rates by Country

Urbanization

Lecture 8

More Than Half of the World’s People Live in Urban
Areas

” Urbanization
” Creation and growth of urban and suburban

areas
 55% of people live in such areas

” Urban growth
” Rate of increase of urban populations
” Immigration from rural areas

” Pushed from rural areas to urban areas

” Pulled to urban areas from rural areas

Three Major Urban Trends

” Three major trends
” Proportion of global population living in urban areas is

increasing

” Number and sizes of urban areas are increasing
” Megacities: more than 10 million residents

” Hypercities: more than 20 million residents

” Poverty is becoming increasingly urbanized
” Mostly in less-developed countries

Three Major Urban Trends

Urbanization in the United States

” Three phases between 1800 and 2015

” Migration from rural areas to large
central cities

” Migration from large central cities to
suburbs and smaller cities

” Migration from North and East to South
and West

” Aging infrastructure

” Deteriorating services

Urban Sprawl

” Urban sprawl

” Low-density development on the
edges of cities and towns

” Contributing factors to U.S. urban sprawl

” Abundant, affordable land

” Automobiles

” Federal and state funding of highways

” Inadequate urban planning

Urban Sprawl

” Suburban sprawl destroys forests, wetlands,
and cropland

” Forces people to drive almost
everywhere

” Contributed to economic deaths of many
central cities

Urbanization Has Advantages

” Cities
” Centers of economic development,

innovation, education, technological
advances, social and cultural diversity,
and jobs

” Better medical care than rural areas
” Recycling economically feasible
” Reduce stress on wildlife habitats
” Mass transportation typically available

Urbanization Has Disadvantages

” Large ecological footprints
”Consume 75% of the world’s resources

” Lack of vegetation
” Water problems

”Runoff, flooding, wetland degradation
” Pollution and health problems

”Air and water pollution
”Solid and hazardous wastes

Urbanization Has Disadvantages

” Excessive noise
” Noise pollution impairs or interferes with

hearing, and causes stress and accidents

” Local climate effects and light pollution
” Cities tend to be warmer, rainier, foggier, and

cloudier than rural areas
” Urban heat island
” Artificial light has affected some species

(disorientation, natural behavior, higher
predation levels, disrupts light sensitive cycles,
higher mortality rates).

Poverty and Urban Living

” Slums
” Areas dominated by dilapidated housing
” Squatter settlements and shantytowns
 Scavenged materials, on unoccupied land

without the owner’s permission

” Terrible living conditions
 Lack basic water and sanitation
 High levels of pollution

Cities Can Grow Outward
or Upward

” Compact cities
” Hong Kong, China

” Tokyo, Japan

” Mass transit

” Dispersed cities
” The United States and Canada

” Car-centered cities

Pros and Cons of Motor Vehicles

” Advantages
” Mobility and convenience

” Provides jobs

” Production and repair of vehicles

” Supplying fuel

” Building roads

Pros and Cons of Motor Vehicles

” Disadvantages
” Accidents kill 1.25 million people per

year globally and injure another 50
million

” Kill 50 million wild animals and
pets per year

” Largest source of outdoor air pollution

” Helped create urban sprawl and car
commuter culture

” Traffic congestion

Reducing Automobile Use

” Full-cost pricing–environmental gas tax
” Consumer education

” Funds for mass transit and bike lanes

” Opposition from car owners and industry

” Raise parking fees

” Charge tolls on roads, tunnels, and
bridges

” Car-sharing networks

Alternatives to Cars

” Foot power
” Bicycles
” Buses
” Heavy-rail systems

” Subways, elevated rail, and metro trains

” Light-rail systems
” Streetcars, trolleys, and tramways

” Rapid-rail system between urban areas

Conventional Land-Use Planning

” Land-use planning
”Governments control uses of certain parcels of land by legal and

economic methods
” Zoning

”Land designated for certain uses
”Mixed-use zoning

Smart Growth

” Set of policies and tools that encourage
environmentally sustainable development

” Uses zoning laws to channel growth and
reduce ecological footprint

” Reduces dependence on cars
” Discourages sprawl
” Many European countries

” High taxes on heating fuel and gasoline
encourages compact cities

Preserving and
Using Open Space
” Urban growth boundary

” U.S. states: Washington, Oregon, and
Tennessee

” Greenbelts
” Canadian cities: Vancouver and

Toronto

” Western European cities

” Municipal parks
” U.S. cities: New York City and San

Francisco

New Urbanism

” Conventional housing development
” Rows of houses on standard-size lots

” Cluster development
” Mixed housing types and green space

” New urbanism: environmental
sustainability
” Walkable, bike friendly neighborhoods
” Mixed use and diversity
” Quality urban design; smart transportation
” Sense of community

The Eco-City Concept: Cities for People, Not Cars

” Eco-city (or green city)
” New model for urban development

” People-oriented, not car-oriented

” Walk, bike, or use mass transit

” High percentage of MSW reused, recycled, or
composted

” Tree planting

” Vertical farms

” Environmental justice

The Eco-City Concept in Curitiba, Brazil

” Ecological capital of Brazil

” Superb bus rapid-transit system
” 85% of the city’s commuters

” Streams and parks

” Recycling programs

” Care for the poor

” High literacy rate

” Population increased fivefold since
1965

Eco-Villages

” 50–150 people come together to design and
live in more ecologically, economically, and
socially sustainable villages in rural and
suburban areas
” Solar and wind power

” Energy-efficient housing

” Organic farming

” 2014: more than 400 eco-villages in over 70
countries

  • Urbanization
  • More Than Half of the World’s People Live in Urban Areas
  • Three Major Urban Trends
  • Three Major Urban Trends
  • Urbanization in the United States
  • Urban Sprawl
  • Urban Sprawl
  • Urbanization Has Advantages
  • Urbanization Has Disadvantages
  • Urbanization Has Disadvantages
  • Poverty and Urban Living
  • Cities Can Grow Outward� or Upward
  • Pros and Cons of Motor Vehicles
  • Pros and Cons of Motor Vehicles
  • Reducing Automobile Use
  • Alternatives to Cars
  • Conventional Land-Use Planning
  • Smart Growth
  • Preserving and Using Open Space
  • New Urbanism
  • The Eco-City Concept: Cities for People, Not Cars
  • The Eco-City Concept in Curitiba, Brazil
  • Eco-Villages
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