Geology 155 - Cal State LA

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Transcript Geology 155 - Cal State LA

Geology 155
Oceanography
Earth System
• System-A set or assemblage of things connected,
associated, or interdependent, so as to form a complex
unity; a whole composed of parts in orderly arrangement
according to some scheme or plan.
• Earth System-composed of interacting physical,
chemical, and biological processes that move and
change materials and energy on earth. The system
provides the conditions necessary for life on the planet.
– Example, plants, which are part of the living system, use solar
energy to change carbon dioxide into organic carbon. Less
carbon dioxide in the atmosphere helps cool the planet. Winds
and ocean currents move heat from the tropics to higher
latitudes, helping to warm the higher latitudes.
Photograph of earth taken on December 7, 1972 by the crew of Apollo 17
from a distance of about 45,000 km, while traveling to the moon. This
image revolutionized our concept of earth, and it is one of the most famous
photographs ever taken.
Image from NASA Earth Observatory.
Right: Earth, the Blue Marble floating in the void-1997. earth as
seen from space based on a montage of data from three
satellites. Image from NASA Earth Observatory.
Goal
• The goal of earth system science is to
obtain a scientific understanding of the
entire earth system on a global scale by
describing how its component parts and
their interactions have evolved, how they
function, and how they may be expected
to continue to evolve on all time scales.
Why Study Oceans
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The CO2 problem, global warming, and the ocean and
all inter-related.
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The ocean strongly influences climate including earth's
surface temperature, by influencing:
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The amount of CO2 in the atmosphere,
The transport of heat from the tropics to polar regions,
The operation of the hydrological cycle,
Earth's carbon cycles.
Most of the oxygen in the atmosphere comes from the
oceans.
The oceans may be responsible for abrupt climate change.
Will global warming plunge the world into the next ice age?
Why Study Oceans?
• Helps control our
climate
• Fisheries and other resources of the
ocean are important.
– Roughly 25% of the protein used
by people comes from fish.
– So much overfishing, fish are
endangered
• The loss of fish changes the
marine food webs.
• Changing food webs affect other life
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and processes in the sea.
Why Study Oceans?
from a 1920 postcard. (Census of Marine Life)
– How many fish can be caught?
http://marinebio.org/i/fishmarket.jpg
Sea Salt - Maio Island -
Why Study Oceans?
• El Niño results from in part from changes
in oceans.
– Oceans influence weather patterns.
– A change of temperature of surface water in
the western north Pacific and in the tropical
Atlantic can cause drought in Texas, and
flooding and mudslides in California.
Why Should We Care About Oceanography?
• Petroleum and
mineral resources
CA gov.
Underwater mineral deposit
Extracting the oil
Why Study Oceans?
• Recreation
LA CO Fire
Why Study Oceans?
• Damaging ocean damages us.
• Coastal pollution
– Coastal pollution seems to be the cause of large scale harmful algal
blooms.
– Coastal pollution seems to be the cause of large scale harmful algal
blooms.
– Pollution also seems to create dead zones in some regions.
– What causes the dead zones off Mississippi and Oregon in the summer?
Oiled Jackass penguins, South Africa.© International Fund for
Anial Welfare (IFAW).
Why Study Oceans
• Coastal processes influence beaches and
those who live and work near the beach.
• Ocean waves erode beaches.
• Structures along beach in most areas will
be destroyed in the long run.
• Cost of protecting structures along the
beaches is very high.
• Why do some beaches lose so much sand
that houses are destroyed?
What is Oceanography?
Oceanography
Subdisciplines
• Geological
• Physical
• Chemical
• Biological
How Do the Oceans Impact Us?
• Hurricane Katrina
• Indonesia Tsunami
Hurricane Katrina
Hurricane Katrina
2004 Indonesia Tsunami
Click image above to view film footage
Indonesia Tsunami
Gaining Knowledge of the Oceans
• Early Voyages
• Science for Voyaging
• Age of Discovery
• Voyaging for Science
Early Voyages
Science for Voyaging
• Polynesia Colonization
• Vikings
• Chinese
• The Age of Discovery
The Age of Discovery
• Prince Henry the Navigator
• Christopher Columbus
• Ferdinand Magellan
Voyaging for Science
• The First Scientific Exploration
• James Cook
• Charles Darwin
• The Challenger Expedition
The Challenger Expedition
• Major Contributions . . .
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First pure scientific expedition
Life was possible below 549 m (1800 ft)
Discovered 4,717 new species
Collected ocean water information
• Temperature, salinity, and water density
• Ocean current and sediment distribution
21st Century Technology
Underwater
• Sonar
• Submersibles
Satellite
• MODIS
• QuikSCAT
• TRMM
Ocean Facts
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About 70% of Earth’s surface is covered by water.
Average depth of the Pacific Ocean = 4,638 m
Average depth of the Atlantic Ocean = 3,872 m
Average temperature = 3.9°C (39.0°F)
Age of oceans = 4 billion years
Hydrologic Cycle
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Continuous cycle of how water moves through different
reservoirs, or from ocean to air, onto land, to lakes and
streams and groundwater back to the sky and ocean.
Stop Here
Hypsographic Curve
• Shows distribution
of elevations and
depths on Earth
( Know how to read graph)
Feedbacks
• Earth systems interact through feedbacks.
– Positive feedbacks lead to instability. They
speed up change in the system.
– Negative feedbacks lead to stability. They
reduce change in the system. See feedbacks.
– In past, systems all natural. Now humans
have influence on planet, changing the
operation of many systems. Because all
systems are interconnected, a change in one
systems influences all other systems.
Science
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The earth is a system that life itself helps to control. Biological
processes interact strongly with physical and chemical processes to
create the planetary environment, Life, the carbon cycle, greenhouse
gases in the atmosphere, and earth's surface temperature are all
interrelated.
Global change is much more than climate change. It is happening
now and it is accelerating. Human activities influence the functioning of
the earth system in many ways
Human drives multiple, interacting effects that cascade through
the earth system in complex ways. Global change is not simply
cause-effect paradigm. hHuman activities interact with each other and
with local- and regional-scale changes in multidimensional ways.
The earth’s dynamics are characterized by critical thresholds
and abrupt changes. Human activities could inadvertently trigger
changes with catastrophic consequences for the earth system. Indeed, it
appears that such a change was narrowly avoided in the case of
depletion of the stratospheric ozone layer.
The earth is currently operating in a no-analogue state. I
Earth Systems