Transcript Introduction to the Earth - FAU

Introduction to the Earth
Basic Terminology and Concepts
Fall 2012 , Lecture 1
Ecosphere
• That part of the earth consisting of five
spheres:
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Atmosphere
Biosphere
Cryosphere
Hydrosphere
Lithosphere
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Atmosphere
• The gaseous layer which surrounds the earth, and
which is held by gravitational attraction. It
consists of layers, the bottom ones of which are:
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Thermosphere > 80 km
Mesopause
Mesosphere
45 - 80 km
Stratopause
Stratosphere 12 - 45 km
Tropopause
Troposphere 0 -12 km
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Hydrosphere
• Earth's water, in any physical state –
 Gaseous
 Liquid
 Solid
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Cryosphere
• Some places on Earth are
so cold that water is a
solid—ice or snow.
Scientists call these frozen
places of our planet the
"cryosphere." The word
"cryosphere" comes from
the Greek word for cold,
"kryos."
•The cryosphere includes Antarctica, the Arctic, and places far away from the
cold poles, at high elevations. Frozen soil can be found high in the mountains
of the United States, the northern reaches of Canada, China, and Russia
• The cryosphere expands during the cold winter months. Seasonal areas of
the cryosphere include places where snow falls, and where soil, rivers, and
lakes freeze.
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Lithosphere
• The outermost part of the solid earth,
consisting of the entire crust and the upper
mantle, from the surface to a depth of about
70 kilometers (km)
• It is stronger and mechanically more rigid
than the asthenosphere (70 - 250 km),
which lies under it
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Interior of the Earth
• Crust –
 Continental (0-40 km, to a maximum of 100km)
 Oceanic (0-10 km)
• Mantle –
 Upper (bottom of crust to 700 km, and includes the
transition zone (350 to 700 km)
 Lower (700 - 2900 km)
• Core –
 Outer (2900 - 4980 km - liquid iron-nickel)
 Inner (4980 - 6370 km - solid)
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Biosphere
• Interface layer between earth's crust,
atmosphere, cryosphere, and hydrosphere
where life is found
• Includes the total ecosystem of the earth
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Ecosystem
• Community of interacting organisms, of all
species – includes
 Plants
 Animals
 Microbes
• Includes interactions of organisms within
this community, and of organism with the
chemical and physical systems of earth
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Biome
• A large community of plants and animals that
occupies a distinct region
• Biomes are usually divided into terrestrial and
aquatic
• Often said to be a group of ecosystems that have a
similar climate and are therefore inhabited by
particular plant and animal species
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Terrestrial Biomes
• Terrestrial biomes, typically defined by their
climate and dominant vegetation, include:
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Grassland
Tundra
Desert
Tropical rainforest
Deciduous and coniferous forests
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Aquatic Biomes
• Freshwater
 Lakes and ponds
 Rivers
• Marine
 Pelagic
 Benthic
 Intertidal zones
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Pelagic Biomes
• Pelagic is derived from the
Greek work pélagos,
meaning Open Ocean
• It is the name for oceanic
water not in direct contact
with a shore or the bottom
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Benthic Biomes
• The benthic zone is the ecological region at the lowest
level of a body of water such as an ocean or a lake,
including the sediment surface and some sub-surface
layers
• Organisms living in this zone are called benthos
 They generally live in close relationship with the substrate
bottom and many are permanently attached to the bottom
• The superficial layer of the soil lining the given body of
water, the benthic boundary layer, is an integral part of
the benthic zone, as it greatly influences the biological
activity which takes place there
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Anthropogenic
• Refers to the impact of human activities on
the natural world, causing changes in the
ecosystem
 Includes impacts on biophysical environments,
and biodiversity
 Impacts vary in magnitude and temporal scale,
and affect the rate at which change occurs
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Environmental Issues
• Changes in the ecosphere caused by:
 Natural processes
 Human activities
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Changes By Other Species
• Humans are not the only species to cause
environmental change
• Cyanobacteria, the first organisms capable
of photosynthesis, gradually changed the
atmosphere of earth from one without
oxygen to one with the present 21% oxygen
content
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So What Makes Humans
Different?
• Humans are the first species to be aware of
their influence
• Humans assume, to some extent,
responsibility for wise management of the
planet
• Humans affect change at rates
unprecedented in the geological record
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Anthropocene
• Term introduced by Nobel Prize-winning
atmospheric chemist Paul Crutzen in the
1970’s
• The term was meant to emphasize the
central role of man in geology and ecology
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Prelude to the Anthropocene
• Significant human alteration of the
biosphere began more than 15,000 years
ago as Paleolithic tribes evolved social
learning, advanced hunting and foraging
technologies, and the use of fire, and used
them to open up forested landscapes and kill
off megafauna
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Rise of Agriculture
• Agriculture impacted earth beginning more
than 8000 years ago.
 Domestication of plant and animal species
 Engineering ecosystems to support them
 Humans introduced a wide range of
unambiguously anthropogenic processes into
the biosphere
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8000 Years Before Present
(YBP)
• 8000 years ago, with a population of just 10 million or so,
humans had already altered as much as a fifth of Earth's
ice-free land, primarily by using fire to clear forest
• Small populations had such extensive impacts because
early agriculture emphasized labor efficiency
 No plowing
 Cultivation had to be constantly shifted to the most fertile areas
 Most of the landscape was in some stage of recovery, giving rise to
"semi-natural" woodlands
 Among the first anthropogenic biomes, or "anthromes".
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Human Transformation of Earth
• Human populations increased and expanded for millennia
 Vast tracts of pristine forest were converted to semi-natural
woodlands and less productive land into rangeland
• Population growth created ever more intensively
transformed anthromes by tillage, irrigation, manuring and
cropping.
• By 1750, more than half of the terrestrial biosphere had
been converted into anthromes,
 Permanent record left in soils, sediments and the atmosphere
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Industrial Transformation
• Rise of industrial systems in the past century has
transformed the majority of the terrestrial biosphere into
intensively used anthromes dominated by novel ecological
processes
• At 7 billion+ and growing, transformation of the last wild
biomes into anthromes continues
 Process will end soon as we reach the limits of the usable
biosphere
 Already, more than 12 per cent of Earth's ice-free land is used
continuously for crops and 16 per cent for livestock
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Start of the Anthropocene
• Together with Eugene Stoermer, Paul Crutzen
proposed a start for the anthropocene as follows:
 “To assign a more specific date to the onset of the "anthropocene"
seems somewhat arbitrary, but we propose the latter part of the
18th century, although we are aware that alternative proposals can
be made (some may even want to include the entire Holocene).
However, we choose this date because, during the past two
centuries, the global effects of human activities have become
clearly noticeable. This is the period when data retrieved from
glacial ice cores show the beginning of a growth in the
atmospheric concentrations of several "greenhouse gases", in
particular CO2 and CH4. Such a starting date also coincides with
James Watt's invention of the steam engine in 1784” (International
Geosphere-Biosphere Programme Newsletter 41, 2000)
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Anthropocene: Pro and Anti
• The term has raised protests from stratigraphers
• Part of the controversy involves a definite marker
for the beginning of the anthropocene
• For those wishing to know more about the
controversy about the use of “Anthropocene” as a
geologic epoch:
• Pro: The Anthropocene: a new epoch of geological
time?
• Anti: Is the Anthropocene an issue of stratigraphy or
pop culture?
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Technology Improvements
• During the last fifty years
• Have greatly contributed to our awareness
of environmental change
 Especially contributing to our knowledge of
global scale processes
• Greatly enhanced out knowledge of the
temporal scale of global change
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Examples of Technological
Change
• Satellite observations
• Computational power
• Rapid communication (Internet)
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Blue Marble Images
• Beginning with the Apollo 8 mission, NASA has published
increasing detailed images of Planet Earth
• NASA's Earth Observing System (EOS) has provided
striking new insights into many aspects of Earth, including
its clouds, oceans, vegetation, ice, and atmosphere, for the
last decade
• EOS satellites are being replaced by the next generation
Suomi National Polar-orbiting Partnership
• Suomi NPP orbits the Earth about 14 times each day and
observes nearly the entire surface
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“Blue
Marble”
Western
Hemisphere
Composite image uses a number of
swaths of the Earth's surface taken
on January 4, 2012
• Image of the Earth taken
from the VIIRS instrument
aboard NASA's most recently
launched Earth-observing
satellite - Suomi NPP
• The NPP satellite was
renamed 'Suomi NPP' on
January 24, 2012 to honor the
late Verner E. Suomi of the
University of Wisconsin.
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“Blue
Marble”
Eastern
Hemisphere
• Image is a composite of six separate orbits taken on January 23,
2012 by the Suomi National Polar-orbiting Partnership satellite
• Four vertical lines of 'haze' visible in this image shows the
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reflection of sunlight off the ocean, or 'glint,'
Changes to the Ecosphere
• Many examples of modification of
ecospheric components have been described
• Representative examples of these
modifications are shown on the following
slides
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Atmospheric Modifications
• Depletion of ozone (O3) in the ozone layer
(stratosphere) which affects UV light
absorption
 Ozone “hole”
 Leads to increased rates of skin cancer
• Acid deposition – introduction of pollutant
gasses into the atmosphere leads to the
formation of “acid rain”
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Atmospheric Modifications cont.
• Modification of the climate system by the
introduction of “greenhouse” gases
 Major gases are carbon dioxide, freons,
methane, nitrous oxide
 Are leading to a warmer earth, and will
increase number and severity of major storms
 May affect short and medium term climate, and
may modify the areas in which food can be
grown
 May create climate refugees
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Hydrological Modifications
• Diagram shows a local
example of the
hydrological cycle
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Hydrological Cycle
Modifications
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Withdrawal of water
Pollution of water
Impoundment of water (dams)
Modifications in erosion and depositional rates
 Silting of rivers and estuaries
 Increased erosion below dams
 Changes in form of precipitation – rain rather than
snow
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Biosphere Modifications
• Mobilization and redistribution of chemical
elements
• Most important carbon (C), nitrogen (N),
and oxygen (O)
 Results in enrichment and depletion of various parts
of the system, leading to problems like red tide,
depletion of soil productivty, etc.
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Biosphere Modifications cont.
• Human activities change natural environment
 Often results in changes in species distribution,
especially in loss of biological diversity (biodiversity)
 Rapid expansion of urban and suburban areas decreases
available habitat
 Deforestation
 Expansion of farming into marginal environments
 Land use that is insensitive to long term changes
• Salinization
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Results of Environmental Change
• Species reduction
 Mass mortality - a large number of individuals die,
which may lead to a new equilibrium distribution, with
a smaller number of individuals of the species in
question, or the original equilibrium may be
approximately restored, to precatastrophe levels
 Extinction - A complete elimination of a species.
Extinction can and does occur naturally - Man's
activities have increased the rate of extinction, with one
recent estimate of 70 species/day
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Natural Events
• Natural events often lead to mass mortality in
many species - extinction may occur in severely
geographically restricted species
• Examples:
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Earthquakes
Volcanoes
Tsunamis
Hurricanes
Small meteorite impacts
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Large Scale Extinction
• Large meteorite impacts can result in mass extinctions
 Example: Cretaceous-Tertiary event that wiped dinosaurs, and
many other species, from the face of the earth
 Immense lava flows
 Example: Permian-Triassic event, 251 million years ago, that
eliminated 90+% of the species on earth – this is the largest
extinction event on earth – From eruption of Siberian Traps and
associated methane release
• Large scale nuclear war would probably have the same
effect
• Anthropogenic change?????
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Environmental Action
• Awareness of environmental change does
not always translate to actions favorable to
the stabilization of the ecosystem
• Why?
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Political Problems
• Politicians make most policy decisions, yet
relatively few politicians have any training
in science or technology
 Some overcome this by relying on
science/technology advisors
• Political considerations may cause them to
rely more heavily on political or economic
advisors, whose perspective is usually
focused on a much smaller time scale
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Economic Gain
• Short term economic gain is a powerful motive
• Example: Drilling for oil in the Arctic Wildlife
Preserve will provide profit, and will very
temporarily stave off the decline in oil production
 This may make the final decrease in petroleum even
more difficult for humans, since we will have built
more automobiles, power plants, etc.
 It will also create immense difficulties for many Arctic
species
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Sources of Pollution
• Pollution may occur from a variety of
sources
• Generally we can divide pollution sources
into two types:
 Point sources – pollution emanating from a
single source, such as a power plant smokestack
 Non-point sources – pollution derived from a
variety of sources, such as smog from
automobile exhaust
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Scope of Environmental
Problems
• Environmental problems are generally split
into one of three groups, with the possibility
of overlap between groups
 Local – effluent introduced into a stream from
an industrial plant
 Regional – acid rain in the northeastern U.S.,
extending into Canada
 Global – Greenhouse gas warming of the planet
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Welcome to the Anthropocene
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