elevation in the sky at noon appears the
same on each of these days.
World Geography
Continental drift
Ecliptic and equinox
Proponents of continental drift believe
that for most of geologic time, there was
one giant landmass on Earth. It is
theorized that in time, this large continent
separated, and the pieces drifted apart.
This is generally the theory of continental
drift. Though others also suggested the
idea, in 1915 the German meteorologist
Alfred Wegener formulated the first
comprehensive theory of continental drift
that incorporated multidisciplinary
evidence. Wegener’s hypothesis was that
the Earth’s crust is heavier, and the
continents are made of lighter rock that
floats atop the crust, similarly to how
icebergs float atop ocean water. In a
rough analogy to the notion of a flat earth
being replaced by that of a rounded one,
Wegener challenged the idea that the
continents were fixed in place by
proposing that they are gradually moving,
about one yard every one hundred years.
The ecliptic is the circle on the celestial
sphere corresponding to the earth’s orbit
around the sun. It crosses the celestial
equator at two points gradually moving
westward along the ecliptic: the
equinoxes, from Latin meaning “equal
night.” Each equinox represents an
intersection of the ecliptic and the
celestial equator. The equinoxes are
points where the sun appears to intersect
with the celestial equator—from south to
north in the spring and from north to
south in the autumn. The dates when each
equinox occurs is also commonly referred
to as an equinox—vernal or autumnal.
The day and the night each last for equal,
twelve-hour durations everywhere in the
world at the vernal equinox, which is the
first day of spring in the Northern
Hemisphere, around March 21; and at the
autumnal equinox, which is the first day
of autumn in the Northern Hemisphere,
around September 23.
Wegener’s theory
A number of scientists believed that Earth
originally had one giant landmass that
eventually broke up, and that the pieces
drifted apart. However, the first to
propose a comprehensive theory of such
continental drift, Alfred Wegener, was
motivated by his observation that the
continents are shaped like pieces of a
giant jigsaw puzzle whose coastlines
could hypothetically fit together, as with
Africa and South America. He also read
research finding identical fossilized plants
and animals on opposite sides of the
Atlantic Ocean. Wegener proposed his
ideas in the early 1900s, but they were
not accepted until the 1960s; today they
are universally accepted. Earth’s tectonic
plates are like jigsaw-puzzle pieces that
move. When plates with continents riding
on them collide, the land can crumple,
forming mountain ranges. Where plates
Solstice
“Solstice” comes from Latin sol, sun, and
sistit, stands, meaning “sun stands still.”
At each solstice, the sun’s apparent
position is the farthest above or below the
celestial equator—approximately 23½°.
At the summer solstice, which is the
longest day in the year, around June 20 to
21, the sun is directly overhead at the
Tropic of Cancer at noon. This day is
designated the first day of summer in the
Northern Hemisphere. At the winter
solstice, which is the year’s shortest day,
around December 22, the sun is overhead
at the Tropic of Capricorn at noon. This
day is designated the first day of winter in
the Northern Hemisphere. For a few days
before and after each solstice, the sun
looks as if it is standing still in the sky; its
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separate, magma rises from inside Earth,
forming volcanoes. Earth’s crust is
thinner at plates’ boundaries/margins
than in plates’ centers, so earthquakes
usually occur at these thinner fault lines.
north across the planet, above the North
American and Eurasian Plates. The
Eurasian Plate underlies Asia and Europe.
The Arabian Plate underlies Egypt, Saudi
Arabia, etc., and the African Plate
underlies Africa. The Indian-Australian
Plate underlies India and Australia;
northeast of it are the small Philippine
and Caroline Plates, abutting the Pacific
Plate.
Plate tectonics
The mechanisms of plate tectonics are
generally accepted as a real geological
phenomenon by the scientific community.
Plate tectonics theory states that the
surface of the Earth is divided into plates,
or slabs, that shift in position. These
plates are an average of about fifty miles
thick. The movements of the plates are
interrelated. Deeper layers of the Earth
are hotter and move faster, underlying
the surface plates. Currents deep in the
Earth influence plate movements. The
plates of Earth’s surface move at rates
averaging up to a few inches yearly. The
majority of Earth’s active volcanoes are
located along or near boundaries between
plates and hence called plate-boundary
volcanoes. This includes Mount St. Helens
and other volcanoes in the “Ring of Fire”
around the Pacific Ocean Basin. Active
volcanoes not near plate boundaries,
called intra-plate volcanoes, often form
chains, including the Hawaiian Islands.
These are believed to have formed
through the Pacific Plate’s moving over an
assumed “hot spot” that generates
magma, forming volcanoes.
Movements among tectonic plates and
faults not related to plate boundaries
The surface of the Earth is divided into
various tectonic plates that shift their
positions. The plates are parts of the
Earth’s lithosphere. In some places, these
plates move apart from each other; this is
called spreading. When one tectonic plate
slides below another plate, this is called
subduction, or underthrusting. When
plates slide horizontally past one another,
this is known as a strike-slip fault. Parts of
continents on the Earth can also undergo
faulting without being located above the
plate boundaries. This faulting can also be
extensional, or of the spreading type;
compressional, i.e. the crustal surface is
moving together rather than apart; or it
can be strike-slip faulting not occurring
along a boundary between plates.
Erosion and weathering
Erosion is the process whereby soils and
rocks making up the Earth’s surface are
broken down and transported. Water, in
ocean waves or flowing in rivers; glaciers;
and the wind are sources of erosion. Bare
rock with no soil protecting it erodes
more quickly. Erosion can result in mass
movements of soil and rock in some cases.
The sun’s heat, the cold of frost, and water
can weaken the composition of rocks; this
is known as physical weathering. These
same forces of heat, cold, and water can
also cause chemical weathering when
they chemically break down the structure
of the minerals in certain rocks, speeding
erosion. For example, limestone is mostly
Locations of tectonic plates
Tectonic plates are shifting segments of
the Earth’s surface. The North American
Plate underlies the U.S. and Canada. The
much smaller Juan de Fuca plate is on the
west coast near the San Andreas Fault.
The small Cocos and Caribbean Plates
underlie Central America. The South
American Plate underlies South America,
with the Nazca Plate to its west and the
large Pacific Plate west of that. South of
these are the small Scotia Plate and the
large Antarctic Plate. Plate boundaries are
undetermined at latitudes of 60° and
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calcium carbonate, soluble by acid.
Rainwater contains carbon dioxide from
the air and hence is acidic. Rainwater
dissolves limestone; this is an example of
chemical weathering.
carved by wind erosion. Softer layers of
sedimentary rock eroded faster than
harder ones, creating jagged profiles.
Coastal erosion is caused by ocean waves
undermining cliff bases, making them
topple. Broken rocks create shingle and
sand beaches. Waves throwing shingle
against the cliffs hasten erosion. Coastal
erosion formed Victoria, Australia’s
Twelve Apostles rock towers, remnants
left after headlands were eroded from
both sides.
Mass movements
Most erosion occurs gradually, in tiny
increments. However, mass movements
are types of erosion that occur suddenly
in large amounts. When rock, soil, or
debris on a slope becomes unstable,
gravity makes it fall downward.
Landslides, avalanches, mudflows, rock
falls, and slumps are mass movements.
Rock movements like avalanches are the
fastest type of mass movement. When a
river or waves erode a slope’s base, or
soft rock or soil gets waterlogged,
downhill motion of a large portion is
called a slump. Broken rock pieces,
combined sometimes with soil, rolling
downhill, form debris slides due to rapid
erosion, often caused where humans clear
hillsides of vegetation. Volcanic
mudflows, or lahars, are composed of
water mixed with volcanic ash. These
form when a volcanic eruption melts ice
and/or from torrential rains. The mud
flows downhill, setting rigidly when it
stops. These mudflows can cause mass
destruction.
Soil creep
Whereas mass movements are types of
erosion that occur suddenly with large
volume, like landslides or avalanches, soil
creep is the opposite—a type of erosion
that occurs very slowly and gradually, too
slowly to be visible in itself. Soil creep
occurs down very steep hillsides. When
soil has been wet and it dries out, or it has
been frozen and it thaws out, these
changes cause the soil to expand and
contract. The topmost layers of the soil
move more quickly than the bottommost
layers underneath. When the soil creeps
downhill, although this happens too
slowly for us to view the movement, its
signs can be found in such results as bent
trees; fence posts and utility poles
leaning; the formation of small terraces
within fields; and soil building up at the
bottom of a hillside or against a wall.
Glacial erosion, wind erosion, and coastal
erosion
Glaciers slowly move downhill due to
gravity’s pull and the forward impetus of
their enormous weight. They are akin to
frozen rivers. As they move, their huge
size and weight carve out deep, U-shaped
valleys with flat bottoms and steep walls.
The surface rocks dragged along under
the glacier by its movement also gouge
valleys into the ground. Wind erosion is
common in deserts, where few plants
grow to anchor the soil in place with their
roots; there is little rain to bind soil
particles together; and thus the wind can
blow sand around easily. Bryce Canyon in
Utah features natural sandstone pillars
Lithosphere, asthenosphere,
hydrosphere, atmosphere, and
biosphere
The lithosphere is the portion of the Earth
consisting of the outer crust, divided into
tectonic plates. It includes the lighter
continental crusts and the heavier oceanic
crusts; and the top part of the earth’s
mantle. The Mohorovicic discontinuity
(“Moho”) separates the mantle and the
crust. The irregularity of this
discontinuity makes it difficult to estimate
the thickness of the continental plates of
the lithosphere, but they are thought to be
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around 185 miles. The lithosphere ranges
in thickness from about 1 mile at the midocean ridges to about 80 miles below the
older oceanic crust. The Earth’s
lithosphere is believed to ride atop the
asthenosphere, a soft layer of partly
molten or semiplastic, low-density rock
material that allows the more brittle
tectonic plates to glide over it. Seismic
waves move slowly through the
asthenosphere, indicating a softer
medium. “Deep-zone” earthquakes, in the
asthenosphere and/or below, may be due
to plates’ sinking into mantle along plate
boundaries.
calm above the weather and winds. The
ozone layer is in the lower part of the
stratosphere. The mesosphere extends
from 30 to 50 miles above the Earth’s
surface. Meteors and meteorites, which
are fragments of rock and dust from
space, burn up when they enter the
mesosphere; we see these as “shooting
stars.” The thermosphere extends from 50
to 280 miles above Earth’s surface and
includes the ionosphere, a layer of ions
(charged particles). Human
communications using radio waves are
bounced from Earth off the ionosphere
and back. The exosphere, 280 to 560 miles
above Earth, is the atmosphere’s outer
layer, adjoining outer space.
The lithosphere is the earth’s crust or
outer surface, divided into tectonic plates
that move. The hydrosphere is the water
on the Earth’s surface in the oceans, lakes,
ponds, rivers, and streams, and the
precipitation and the water vapor in the
atmosphere. The atmosphere is the
bubble of gases that envelops the Earth
and extends about 430 miles into space. It
keeps the Earth’s surface warm and
protects us against meteorites, and its
ozone layer protects us from harmful
solar radiation. Atmospheric gases are 78
percent nitrogen, 21 percent oxygen, and
smaller amounts of argon, carbon dioxide,
and water vapor. Atmospheric pressure is
greater than 14 pounds per square inch of
pressure the air exerts on its
surroundings. It is highest at sea level and
decreases with increasing altitudes. We
do not sense atmospheric pressure as our
body fluids exert counterbalancing
outward pressure. The biosphere is all
parts of the planet where life exists. It
includes air, water, and land.
Climate
Climate is influenced by latitude, i.e.
distance north or south from the Earth’s
equator; height above sea level; and
distance from the ocean. Oceans warm
more slowly than land, but retain heat
longer. Coastal regions are warmed in
winter by sea breezes, which also cool
them and bring rain in summer. Thus
coastal areas typically have mild, wet
climates. The Earth’s curvature causes it
to receive the sun’s rays at various angles.
Regions near the equator receive sun
more directly and in greater
concentration than polar regions, so
tropical areas typically have hotter
climates while polar regions are much
colder. Mountain areas are also cooler
due to their elevation. Because land
masses warm up and cool off faster than
oceans, continental areas farther inland
have more temperature extremes than
coastal regions. Thus continental climates
have hotter summers and colder winters
than coastal areas with milder climates.
Atmospheric layers
The lowest layer of the Earth’s
atmosphere is the troposphere, which
extends about 7 miles into space and
holds about 75 percent of the
atmosphere’s air and water. The
stratosphere extends from 7 to 30 miles
above the Earth’s surface. It is an area of
Biome
A biome is a large ecosystem wherein
plants, insects, animals, and humans live
within a particular kind of climate. Alpine
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Tundra is a biome found on high
mountaintops with cooler temperatures
and thinner air. The Arctic Tundra, near
the Arctic Ocean, has swampy lowland
plains, no trees, and cold temperatures.
South of it is the Coniferous Forest biome
or taiga, also cold but with trees, though
only needled, not leaved, trees and hence
less fertile soil. The Northern
Hemisphere’s mild temperate zone
contains the Deciduous Forest biome,
with fertile soil and abundant life. Desert
biomes comprise about one-fifth of
Earth’s land and exist on every continent
but Europe. Deserts are cold or hot, but
always dry. Grasslands are hot, dry
biomes suited to agriculture. They are
called prairies in the U.S.; veldts in Africa;
savannas in Africa and South America’s
tropical zones; steppes in Eurasia’s
temperate zones; and pampas in South
America’s temperate zones. They exist on
all continents. Tropical rain forest biomes
are often near the equator.
the environmental damage of the
greenhouse effect.
Tropical rain forest biomes are hot and
wet. Their combination of high
temperatures and heavy rainfall promote
their characteristic lush growth of flora
and fauna. Brazil, the largest country on
the continent of South America, contains
nearly half of the tropical rain forests in
the world. Tropical rain forests are
frequently located near the Earth’s
equator. In addition to South America,
they exist in Central America, Africa, Asia,
and many islands in the Pacific. There are
other types of rain forest biomes in the
world as well. For example, in the Pacific
Northwest of the United States, there is a
“temperate rain forest.” It receives the
heavy rain typical of this region, but also
has cooler temperatures, so its trees are
all evergreens. In northern Australia,
there is a “dry rain forest.” It receives the
rain needed to grow a forest, but also has
a dry season without rain every year.
Rain forests
Tropical rain forests contain more than
15 million plants and animals, the most in
the world. They get a minimum 70 inches
of rain annually. Many medicinal plants
grow only in tropical rain forests. They
have three levels: The canopy of 100- to
200-foot-tall trees blocking most sunlight
to lower levels; the understory with
smaller trees, palms, vines, ferns, shrubs,
and other plants; and the forest floor,
which grows herbs, fungi, and mosses.
This biome’s heat and moisture
encourage growth. Its many trees/plants
include bamboo, banana, rubber, and
cassava. Its many animals include jaguars,
lemurs, orangutans, marmosets,
anteaters, brocket deer, sloths, toucans,
and parrots. Tropical rain forests exist in
Asia, Africa, Central America, South
America, and on many Pacific islands.
Rain forest biomes are endangered by
human activities: cutting trees for wood
and burning them to clear land for
farming. Cutting and burning also add to
Mountains
Every world continent has mountains.
There are two major systems or belts
containing many of them: The “Ring of
Fire” or Circum-Pacific Chain goes from
the Americas’ west coast, through New
Zealand and Australia, and through the
Philippines to Japan. The Tethyan or
Alpine-Himalayan mountain belt, the
other major system, goes from the
Pyrenees mountain range in Spain and
France, through the European Alps, to the
Asian Himalayas range, and ends in
Indonesia. There are some single
mountains, but mountain ranges are
common. Mountain biomes are cold and
windy due to high elevations. Altitudes
also cause lower atmospheric oxygen.
Forests exist at lower elevations, while
the highest ones lack trees. Location and
altitude determine flora types. Fauna
adapted to mountains include the
mountain goat, ibex, mountain lion, puma,
sheep, and yak.
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include snakes, lizards, frogs, toads, and
camels in hot deserts; and Adélie and
Emperor penguins in the Antarctic.
Grasslands
Grasslands are inland biomes with
climates that are hot and dry, but not as
dry as deserts. They do not get enough
rain to grow many trees, but do grow
large fields of grasses. They include
tropical and temperate grasslands. Their
climates are perfect for growing crops. In
the U.S., prairies are grassland biomes
used for growing grain crops and grazing
cattle. Fauna in grassland biomes are
limited in variety. Original animal species
on American prairies included bison and
wolves, which have been hunted until
they are scarce. Mule deer and prairie
dogs also live there today. Lions, giraffes,
and zebras live in African grassland
biomes or savannas. Lions also live in
Asian grassland biomes. Grasslands have
different names throughout the world:
Prairies in North America; pampas in
South American temperate zones and
savannas in South American and African
tropical zones; veldts in South Africa; and
steppes in Eurasia’s temperate zones.
Deciduous forests
Deciduous forests have trees that lose
their leaves in autumn. Deciduous forest
biomes exist in the mild temperate zone
of the Northern Hemisphere, including
east Asia, Europe, and eastern North
America. Humus from decayed fallen
leaves affords much plant and animal life,
including oak, maple, beech, and ash
trees; berries, wildflowers, and many
types of insects. The American deciduous
forest biome hosts numerous animal
species, including American gray
squirrels; deer; raccoons; rabbits; wood
mice; and birds, such as finches, cardinals,
and woodpeckers and many others.
Because the deciduous forest biome
features fertile soil, most of these forests
in Europe have been destroyed by
humans to clear land for farming and
building houses. Much deciduous forest
growth has also been cleared in the
United States, but many forest areas also
remain, protected by the national and
state parks systems and by
conservationists.
Deserts
Desert biomes receive so little rain that
they host less plant and animal life than
other biomes. Europe is the only world
continent with no desert. Deserts are
always arid, but can be hot or cold. The
Gobi and Antarctic are cold deserts; the
Sahara and Arabian are hot deserts. North
America has four major deserts: the Great
Basin, a cold desert including parts of
Oregon, Nevada, Utah, and Idaho; and
three hot deserts: the Mojave Desert in
southwestern California plus parts of
central California, Nevada, Utah, and
Arizona; the Sonoran Desert, in California
and Arizona in the U.S. and Sonora, Baja
California, and Baja California Sur in
Mexico; and the Chihuahuan Desert in
New Mexico, Texas, and Arizona in the
U.S. and Chihuahua, Coahuila, Durango,
Zacatecas, and Nuevo León in Mexico.
Desert flora are mostly cacti, including
saguaro, aloe, yucca, and ocotillo. Fauna
Coniferous forests
Coniferous forest biomes differ from
deciduous forest biomes in that their
trees are mainly cone- and needle-bearing
evergreens rather than trees that grow
leaves and lose them in the autumn, i.e.
deciduous trees. The decomposition of
dead leaves from deciduous trees yields
rich soil, whereas coniferous forests lack
this feature. The coniferous forest biome
is located south of the Arctic tundra, from
Alaska across North America, the Atlantic
Ocean, and across Eurasia. The world’s
largest expanse of coniferous forest is in
the Northern Hemisphere,
circumnavigating the globe; this is called
the taiga. The majority of commercial
softwood timber used to manufacture
paper products in the world comes from
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the taiga. Coniferous forests have colder
temperatures and feature well-adapted
evergreen trees such as hemlocks, firs,
and spruces. Fauna adapted to the area
include moose, snowshoe rabbits, red
foxes, ermines, and birds, including great
horned owls and crossbills.
Development Report. This report is
written by world development scientists,
scholars, and members of the UNDP’s
Human Development Report Office. The
Human Development Report includes the
results of the Human Development Index
(HDI), which summarizes world human
development and suggests if a nation is
underdeveloped, developing, or
developed, according to variables like life
expectancy, literacy, education, and gross
domestic product (GDP) per capita.
Arctic tundra
The world’s coldest biome is the Arctic
tundra. It includes most of Greenland,
Iceland, Lapland, Finland, Scandinavia,
Siberia in Asia, Canada, and Alaska. For
almost half the year there is no sunlight,
so winter temperatures are often under 30° (below zero). Areas north of the
Arctic Circle also have continuous
sunlight during summer months (hence
the expression “land of the midnight
sun”). Permafrost, i.e. permanently frozen
subsoil, prevents trees from growing in
this biome, which consists of low-lying,
swampy plains. A thin topsoil layer thaws
in summer, making pools, lakes, and
marshes, and allowing many insects like
mosquitoes, midges, and blackflies to
breed, providing food for over 100
species of visiting migrant birds. Animal
species native to this biome include Arctic
foxes, caribou, polar bears, and grey
wolves. Flora includes lichens, cushion
plants, and small shrubs. In early autumn,
the Arctic is also known for beautiful
wildflowers.
Historical background
The United Nations has been calculating
its Human Development Index (HDI) for
all nations with UN membership since
1975. The United Nations Development
Program (UNDP) published its first
annual Human Development Report,
which included the HDI for member
nations, in 1990. A Nobel Prize Laureate
in Economics from India and Pakistan’s
finance minister, also an economist, were
leaders in publishing this first report. The
UNDP found that per-capita real income
was not a sufficient measure of national
prosperity and development because
such figures do not necessarily indicate
that a nation’s citizens are faring better
overall. Therefore, the UNDP’s first
Human Development Report included the
HDI and considered additional variables,
such as the average life expectancy, health
status, education, employment, and
leisure time of the members of a country’s
population.
UNDP and HDI
The United Nations Development
Program (UNDP) is concerned with
human development. To quote a
statement from the UNDP, human
development involves “creating an
environment in which people can develop
their full potential and lead productive,
creative lives in accord with their needs
and interests. People are the real wealth
of nations. Development is thus about
expanding the choices people have to lead
lives that they value.” The UNDP
commissions publication of the Human
Focus, components, and computation
The United Nations’ HDI is a
measurement intended to evaluate the
growth and achievements in human
development of any one of its member
nations. Today it uses three component
dimensions. The first is health, which is
measured by life expectancy at birth.
Countries with higher average life
expectancies rank higher than those with
lower ones. The second dimension is
knowledge. This is assessed by measuring
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a nation’s adult literacy rate, together
with gross ratios of student enrollments
in primary, secondary, and university
levels of schools for an overall national
knowledge level. The third dimension is
standard of living. This is measured in
terms of purchasing power parity, based
on U.S. dollar amounts, through the percapita gross domestic product (GDP).
Using raw study data, a separate index is
computed for each dimension. A formula
with minimum and maximum values of
the range is used to make an index from
the raw data. A nation’s HDI is calculated
as an average of the indices for the three
dimensions.
U.S.’s long-term progress
Human Development Index (HDI)
measures of progress can be compared
among members of the Organization for
Economic Cooperation and Development
(OECD) by comparing their annual
Human Development Reports for United
Nations member countries. America’s HDI
values were similar to those of
Switzerland and Australia in 1980.
America’s HDI was higher than
Switzerland’s from 1980 to 2010, but
followed a similar curve. Australia’s HDI
increased sharply from 1990 on,
surpassing America’s in the 1990s. The
2010 average of HDIs in OECD countries
was 0.879, and 0.878 for countries with
“very high human development.”
America’s 2010 HDI exceeded both at
0.902. Canada and Australia are
considered America’s “OECD neighbors”
for having similar population sizes and
HDI ranks. Canada’s HDI rank is 8;
Australia’s is 2; and the United States’ is 4.
Recent global Human Development
Reports
The United Nations Human Development
Program’s Human Development Report in
2009 contained data through 2007. The
highest ranked UN member nations were
deemed to have “Very High Human
Development.” The top five such
developed countries were (1) Norway, (2)
Australia, (3) Iceland, (4) Canada, and (5)
Ireland. The 2010 report includes data
through 2010, and reviews trends and
patterns of the past several decades to
inform future research and policy for the
first time. The 2010 20th Anniversary
Report introduced, and the 2011 Report
updates, these new additional indices: the
Inequality-Adjusted HDI; the Gender
Inequality Index; and the
Multidimensional Poverty Index. Global
improvements have transpired recently
in health, education, income; and people’s
power to choose leaders, influence public
policy, and share knowledge. However,
there have also been recent reversals in
such areas as southern Africa and the
former USSR, particularly in health.
Nationally and internationally,
unsustainable production and
consumption, and increasing inequalities
have also been documented and targeted
for policy change.
GII
The UN’s new Gender Inequality Index
(GII) for Human Development Reports
divides gender inequities into three
categories: reproductive health,
empowerment, and economic activity.
Maternal mortality rates and adolescent
fertility rates measure reproductive
health. Secondary and higher education
attained by each gender and share of
parliamentary seats held by each indicate
empowerment. Rate of participation in
the labor market by each gender
measures economic activity. The inequity
between male and female achievements
in each dimension contributes to human
development loss, shown by the GII. In
America, women held 17 percent of
government seats. 95 percent of women
and 94 percent of men had secondary or
higher educational levels. 69 percent of
women participated in the labor market,
while 81 percent of men did. U.S.
adolescent fertility was 36 per 1,000 live
births. Maternal mortality was estimated
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(using 2008 data) at 11 per 100,000 live
births. These components yielded a rank
for America of 37 out of 138 countries.
Australia ranked 18 and Canada 16 on
this measure.
plenty of fresh water from the Hudson
River, its tributaries, and other creeks;
and had trees and other natural resources
for building materials. It also had natural
protective barriers to movement inland in
the Catskill and Appalachian mountains.
An opposite example is Bhutan, a small
country in the Himalayan mountains.
High altitudes, very rough terrain, and
harsh climates in most areas present
great challenges. Only 2 percent of
Bhutan’s land, mostly in the highlands, is
arable, exacerbating the difficulties. Most
of Bhutan’s population thus lives along
rivers in the highlands south of the
mountains.
Criticism
The UN has been calculating HDIs for its
member nations since 1975, but did not
publish these until 1990, in its first
annual Human Development Report. One
objection to HDI by critics is that its focus
is on national performances and ranking
these, but it does not take ecological
considerations into account. This seems a
valid complaint. Another criticism is that
the HDI is redundant in evaluating
elements of human development that
have already been extensively studied
globally. This is also valid, though some
redundancy in reporting such statistics
and knowledge can be valuable. Critics
additionally find that because an HDI is
calculated independently for each nation,
this measure does not view countries
from a global perspective. While it is true
that each nation has a separate HDI, the
UN does provide several documents that
allow comparisons of HDIs among
different countries, including relative
rankings. The HDI remains valuable for
regularly alerting governments,
international groups, and corporations to
health, education, and other aspects of
development besides income.
Situation is how a place/area is situated,
or located, relative to its surroundings
and to other places. Situation includes
variables such as accessibility; proximity
to natural resources/raw materials if they
are not on-site; and connections to other
places. For example, the Himalayan nation
of Bhutan is difficult to live in because of
its site, with mountainous terrain,
inhospitable climates, and little arable
land. However, its situation presents
some advantages. The mountains prevent
easy access; therefore others have never
invaded Bhutan’s center. Bhutan also
controls most strategic mountain passes
in the Himalayans, including the only ones
leading to and from the country, so it is
called the “Mountain Fortress of the
Gods.” Its situation has also supported
Bhutan’s isolationist policies and has
reinforced its highly separatist religious
and cultural traditions.
Site and situation in settlement
patterns
Two major concepts in urban geography
are site and situation. Site is a particular
physical location and the characteristics
of its landscape. Site features include
landforms, e.g., protective mountain
barriers and natural harbors; climate
conditions; water supply; local minerals;
soil quality; vegetation; and wildlife. For
example, many Europeans coming to
America settled in New York City because
it is on the coast and has a natural harbor;
An example of some of situation’s
disadvantages can be found in the
Canadian Eastern Provinces: New
Brunswick, Newfoundland, Labrador,
Nova Scotia, and Prince Edward Island.
The isolation of these places from the rest
of Canada makes their manufacturing or
the engaging in the little possible
agriculture too costly to be possible. Few
natural resources are close enough. Many
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natural resources are off the coast, so
they are controlled by the Canadian
government because of maritime laws.
Moreover, dwindling fish populations are
undermining the historical fishing
economies. Thus the situation of these
provinces gives them some of the most
depressed economies in Canada.
is expected to continue during the 21st
century, but not to continue at as rapid a
rate as it progressed during the 20th
century. In the 45 years from 1999 to
2044, the numbers of people living in the
world are projected to increase by 50
percent, or from 6 billion people to 9
billion people.
World population
Census Bureau’s International Data Base
and changes between 1950 and 2050
The U.S. Census Bureau has an
International Programs Center for
Demographic and Economic Studies. Its
research is sponsored by organizations
that fund the Census Bureau’s
International Data Base. For more than
twenty-five years, this data base has
supplied demographic information to
national governments, academic
institutions, other organizations, and the
public. It provides a variety of
demographic indicators for world areas
and countries having populations of 5,000
or more. According to this source, from
1950 to 1951 the world population
growth rate was 1.5 percent. It exceeded
2 percent in the early 1960s owing to
reduced mortality rates. Thereafter, it
slowed due to increased access to and use
of contraception. The growth rate
dropped from 1959 to 1960 because of
China’s Great Leap Forward: massive
social reorganization reduced agricultural
production; combined with natural
disasters, this made China’s fertility rate
fall by nearly half and its mortality rate
rise steeply. The world population growth
rate is projected to fall from less than 1
percent in 2010 to 0.5 percent by 2050.
Ten most populous nations
According to the U.S. Census Bureau’s
International Database, the ten most
populous nations in the world as of 2011
are: (1) China, with 1,336,718,015 people;
(2) India, with 1,189,172,906 people; (3)
the United States, with a population of
311,050,977; (4) Indonesia, having a
population of 245,613,043; (5) the largest
country on the continent of South
America, Brazil, which has a population of
203,429,773; (6) the country of Pakistan,
which is populated by 187,342,721
persons; (7) on the continent of Africa,
the country of Nigeria, which has a
recorded number of 165,822,569 people
living in it; (8) bordering on India, the
People’s Republic of Bangladesh has a
recorded population consisting of
158,570,535 people; (9) Russia, which
has a documented population in 2011 of
138,739,892 individuals; and (10) the
nation of Japan, which as of 2011 was
recorded by the census as having a
population made up of 127,469,543
citizens.
Growth from 1959 to 1999 and projected
growth
In 1950, the population of the world was
estimated to be over 2.5 billion people. By
1960, it had reached 3 billion people.
From 1959 to 1999, global population
numbers actually doubled within a period
of only 40 years, from 3 billion people to 6
billion people. According to the U.S.
Census Bureau’s International Data Base
and current projections regarding the
near future, the global population growth
Yearly changes and growth rates
One index that demographers look at is
the rates at which world population has
grown historically and is expected to
grow in the future. In addition to growth
rates, another way to look at world
population is by examining annual
changes in the total numbers of the world
population. Indices of the world’s total
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population per year can give different
information from indices of the rates at
which the world population has grown
and will grow. For example, according to
the U.S. Census Bureau’s International
Data Base, annual rates of world
population growth had peaked before the
late 1960s. However, the peak of annual
increases in world population was
attained in the late 1980s. This is because
world population was higher in the 1980s
than in the 1960s. An annual increase in
world population of about 87 million was
reached shortly before 1990.
that decade. The 1991 world population
change was also the decade’s highest at
84,931,873. The 1990s’ lowest growth
rate of 1.275 percent and lowest
population change of 76,756,788 were
both in 1999. From 2000 to 2009, both
growth rate and population change have
steadily fallen: growth rate from 1.267
percent in 2000 to 1.113 percent in 2009,
and total change from 77,234,911 in 2000
to 75,635,235 in 2009. However, growth
rate rose to 1.129 percent, and annual
change to 77,515,783, in 2010. Mid-year
growth rate has fallen back to 1.113
percent in 2011, while population change
is 77,280,910—lower than in 2009, even
though growth rates were equal in 2009
and 2011.
The highest annual growth rate of the
world population in the 1950s was 1.979
percent in 1956, but annual change that
year was 56,107,849; it was higher at
56,849,272 in 1957, while the 1957
annual growth rate was 1.967 percent,
lower than it was in 1956. The 1960s’
highest growth rate was 2.226 percent in
1963; annual change was 71,443,536 that
year, but was higher at 75,687,612 in
1969, when annual growth rate was 2.081
percent, lower than in 1963. In the 1970s,
the world population’s annual growth
rate was its highest at 2.098 percent in
1970, and the total annual world
population change was also highest that
year at 77,893,083. However, the lowest
annual growth rate of that decade was
1.653 percent in 1979, with an annual
population change of 72,398,249—
greater than the lowest annual change of
71,275,288 in 1975, when the growth rate
was 1.742 percent—higher than it was in
1979.
Population pyramid
A population pyramid is a graphic
representation showing distribution of
different age cohorts/groups within a
particular human population, usually of a
certain country or region of the world.
When an area’s population is healthy, the
graph’s ideal overall shape is pyramidal. It
is akin to a blueprint depicting population
dynamics. Much information about a
population, broken down by sex and age,
can be acquired from such graphs,
providing insights to the extent of a
population’s development and how many
individuals from each age group live in
the area. Population pyramids are also
called age structure diagrams. They are
usually made of two bar graphs back-toback, with males on the left and females
on the right, represented in raw numbers
and/or percentages of the population.
Population is plotted on the X-axis and
age on the Y-axis. Ecologists also use
pyramids to evaluate a population’s
overall age distribution, hence its
reproductive capacity and probability of
perpetuation.
Demographers recognize three general
structural patterns in population
pyramids: constrictive, expansive, and
According to the U.S. Census Bureau’s
International Data Base, 1980’s mid-year
world population growth rate of 1.861
percent was that decade’s high, but
1980’s world population change was
82,869,936—lower than 1989’s change of
87,363,581, when the growth rate was
only 1.679 percent. World population
grew at a rate of 1.580 percent in 1991,
the year of highest growth rate during
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stationary. A constrictive pyramid has
fewer members in younger age groups, so
its appearance constricts with lower ages.
Most United States populations show a
constrictive pattern because birth rates,
and hence population growth, have
diminished ever since the unprecedented
population explosion of the Baby Boom
generation. An expansive pyramid has
more young members and fewer older
members in the population, so its
appearance expands for lower age
cohorts. Developing nations typically
have expansive patterns because their
birth rates are high, but life expectancies
are shorter due to harsh living conditions.
Stationary pyramids show roughly
equivalent numbers in all age cohorts,
with the oldest groups tapering slightly.
Sweden is an example because its birth
rates are constant and fairly low, and its
quality of living conditions is high.
developing countries; therefore, the
world’s population has exponentially
increased. Net migration is the difference
between in-migration and out-migration.
Net migration plus natural increase
equals overall population growth.
Demographic transition model
The demographic transition model is an
important tool used in population
geography. It is a model that divides the
development of a country into four stages
to examine how this development
influences changes in its population. In
the first stage, birth rates in a population
are high, but so are death rates. Thus any
natural increase is small, and so is overall
population size. In the second state, a
population has high birth rates, but
mortality rates are low. This results in
rapid population growth. Many of the
least developed countries are in this
second stage, before population growth
has had time to catch up to and exceed
available resources and increase
mortality rates. In the third stage of this
model, both the death rate and the birth
rate decrease as the society has
developed further. These trends
contribute to slower population growth.
In the fourth stage, the declines of the
third stage have made both birth and
death rates low, so natural population
increase is also low.
Population geography, population
distribution, population density, and
growth and change
Population geography is closely related to
demographics. Population distribution
focuses on where people live in the world.
Denser populations are associated with
areas having milder climates and greater
social, economic, and political
development of the peoples inhabiting
them. Population density is the average
number of people living in an area,
obtained by dividing the total number of
individuals by the total area in square
miles or kilometers. In studying
population growth and change, natural
increase is the ratio of birth to death rates
in a population. Historically, global
natural increase was close to zero
because births and deaths were roughly
equivalent. However, today’s
improvements in health care and
standards of living have decreased
mortality rates and increased life
expectancies. Birth rates in developed
nations have declined, but remain high in
Today’s process of globalization
World countries today are increasingly
interconnected economically, politically,
and culturally. One key element is
technological progress in
communications and transportation. With
much faster air travel; international
telephone capability; faxing, instant
messaging, video conference calling, etc.,
people can connect with others all over
the globe. This has brought a
metaphorical “shrinking” of the world, as
distance poses a far lesser obstacle today
than historically. Increased transport
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technology, plus overall enhanced
awareness and opportunity, have
facilitated migration to escape dangerous
situations and find new homes and/or
jobs. Electronic funds transfers ease
global money movement; coupled with
greater perceived investment
opportunities in developing nations, this
facilitates movement of capital as well as
people. Globalization promotes the
diffusion of new knowledge. Many
businesses outsource foreign employees
to save money. Global awareness has also
fostered more international nongovernmental organizations (NGOs), e.g.
Doctors Without Borders and Amnesty
International, pursuing global concerns
like climate change, child labor laws, or
energy use.
Negative aspects
In addition to its many positive aspects,
globalization also has negative elements.
While outsourcing work saves employers
money and provides jobs for citizens of
other countries, it also deprives the
natives of the outsourcing nation of job
opportunities. While international
interactions afford exposure to foreign
cultures, they can also blur cultural
differences, increasing global uniformity
and decreasing cultural individuality.
Globalization can introduce invasive
species that could devastate some nonnative ecosystems. Increased global travel
and interaction could also cause
worldwide spread of diseases.
International regulations have not
developed commensurately with
globalizing activities, so the safety of
humans and the environment are at risk
without adequate means of governing
such global interactions. Globalization has
enabled developing nations to acquire
loans from Western-based international
organizations like the World Bank and the
International Monetary Fund. However,
the negative aspect is that these groups
usually apply a Western perspective to
non-Western circumstances, so the
recipients fail to achieve progress using
these funds.
Positive aspects
Globalization connects world nations, so
more developed nations invest more of
their capital in less developed nations.
This increases the chances for economic
success and higher standards of living in
developing countries. Worldwide
business competition stimulates
innovations and creativity, and also keeps
prices for products and services under
control. Globalization enables developing
countries to benefit from the newest
technologies without suffering most of
the “growing pains” of developing such
technology independently. Globalization
improves the capacity of the world’s
peoples to communicate, interact, and
coordinate their activities; it also raises
awareness of world issues and fosters
cooperation. Thus national governments
are better able to collaborate toward
shared common goals. Additionally,
globalization gives the people of different
nations more access to contributions
from other cultures, as in foods, fashions,
films, TV, music, sports, literature, leisure,
and many other aspects of culture, and
hence more cultural choices.
Greenhouse effect
The natural greenhouse effect warms
Earth’s atmosphere. Sunlight passes
through the atmosphere’s thermal
blanket of greenhouse gases, which
consist of water vapor, carbon dioxide,
methane, nitrous oxide, and ozone. The
Earth’s surface reflects infrared radiation
from the received light back toward
space, but part of it is trapped in the
thermal blanket, maintaining an average
planetary temperature of around 60°F,
which is ideal for life. Since the Industrial
Revolution, humans have added excessive
amounts of gases to the naturally existing
greenhouse gases through agriculture,
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industry, and transportation. For
example, deforestation adds carbon
dioxide to the air. Breeding more cattle
adds methane to the air from gas expelled
by the cows. Burning fossil fuels adds
carbon dioxide, methane, nitrous oxide,
and ozone to the atmosphere. These
surplus greenhouse gases trap more heat,
raising global temperatures to levels that
will be less ideal and more threatening to
life.
warming is caused by human activity and
must be addressed. At the 1992 UN
Conference on Environment and
Development, more than 150 nations
signed a binding treaty to reduce climate
change. But in 1994, the IPCC found the
1992 treaty’s provisions insufficient,
projecting temperature increases of 1.44°
to 6.3°F by 2100 without action, and of 1°
to 3.6°F with action to reduce emissions.
The UN’s 1997 international Kyoto
Protocol was ratified by more than 125
nations, effective 2005; but America’s
Bush administration abandoned it, a
severe setback since America produces
roughly one-fourth of global greenhouse
gases. America, Australia, China, India,
Japan, and South Korea signed a 2005
agreement outside the Kyoto Protocol to
reduce emissions through new
technologies.
Before the Industrial Revolution, the
amounts of natural greenhouse gases in
the Earth’s atmosphere kept the planet’s
temperatures at levels most hospitable to
plant, animal, and human life. However,
increased human industry since then has
produced additional greenhouse gases
beyond what was natural. This is affecting
our global environment. For example,
higher temperatures are causing more of
the polar ice caps to melt. Melting polar
ice causes rising sea levels and coastal
floods. Some island societies’ habitats are
actually sinking, so they must relocate.
Additionally, polar bears cannot find
sufficient ice floes to hunt enough seals to
survive. It is projected that supplies of
drinking water depending on snowmelts
will be disrupted. Agriculture will be
profoundly altered. Ecological niches will
vanish, causing species extinctions. Also,
tropical storms and tropical diseases are
both expected to become more frequent.
Debate over global climate change
Some skeptics think climatologists’
computer models simulating world
climate cannot be accurate for a complex
topic with so many unknowns. Some also
attribute climate change to normal global
fluctuations. However, reputable
international institutions like the
Intergovernmental Panel on Climate
Change (IPCC) find much of global
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