Transcript Document

Course definition
• Can’t understand planetary processes including
oceanography without understanding the planet
– Planet includes: atmosphere, geosphere, hydrosphere,
biosphere
– Each component has its sub-discipline but all feedback
upon each other
– Why oceanography? The ocean plays a huge part in all
components – climate, biodiversity, heat balance, etc.
– We start with the big bang and end with the future
• Need to understand relationships and feedbacks to
understand past, present and future conditions
System
• Interconnectedness of components
– Can’t understand one part without the other
– Can’t predict one part without considering the others
• System – a functional unit composed of
interconnected parts (components)
– Scales – micro to mega, depends on your definition
– Biological systems easiest to visualize and on the right
timescales – human body; ecosystems, etc
– Ecosystem collapse
The Earth System
• Mass and energy balance – on earth mass
essentially closed, energy is not
– Other budgets – examples, your garden, your body?
• System – entity composed of interconnected parts
(components)
– Biological systems – human body; ecosystems, etc
• The Earth System
– Comprised of components where mass, material or
energy exchange can be opened or closed
Four components in the Earth System: solid earth, water, gas, biota
The Earth Sub-systems
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What are they?
What are the major reservoirs?
Where are there exchanges?
What are the exchanges? Mass, energy?
Are the fluxes between compartments equal? Will
they stay equal? What is equilibrium?
• What are the turnover times?
• Where are the interactions between systems?
Interactions
• Self-regulation
• Feedbacks loops – how does earth stay
habitable
– Positive feedbacks
– Negative feedbacks
Reductionist Approach
• State the problem
• Find a reason
– At what point in time
– At what physiological state
– Under what physical and chemical conditions
Systems Approach
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Relationships
Synthesis
Evolution of interactions
How interactions change under different
scenarios
• Self-regulation
– Positive feedbacks
– Negative feedbacks
Earth’s organization
• Highly organized – why?
• Self-organization
– Energy cycling
– Feedbacks among system components
Climate change
• Greenhouse effect – radiative effect
– Climate observations (Keeling curve – atm. CO2 on
Mauna Loa, Hawaii – 1958-present)
– Independent data sets – ice cores, etc
– Time scales, rates of change
• Greenhouse gases
– Many and diverse (H2O, CO2, CH4, N2O and aerosols)
– Some completely anthropogenic (freons [CFCs])
– Anthropogenic emissions by country – industrial vs.
land use changes
– Rate of change of production
• C cycling
The Greenhouse Effect
• Necessary for life on earth – and its natural
• Controls the earth’s climate
• Greenhouse gases absorb outgoing IR radiation
What is unnatural or due to humans (anthropogenic)
Impact on Global Surface Temperature
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400,000
Years before present
Vostok ice core records
Glacial pCO2 minima ~180 ppm
change of about 100 ppm over 100,000 years
0.001 ppm/year
Change of ~80 ppm
0.4 ppm/year
What is unnatural or due to humans (anthropogenic)
Use of fossil fuels
Deforestation
750 – 800 ppm
2100
Rising atmospheric pCO2
Ozone depletion
• Political success
• Tractable by eliminating
a few chemicals (CFCs)
Atmosphere & Ocean
• Gases and water freely exchange at the oceanatmosphere interface
• Movement of air (and water) by wind help minimize
worldwide temperature extremes.
• Weather is influenced by the movement of water in
air (state of the atmosphere at a specific time and
place)
• Climate is the long-term average of the weather in an
area
• Interaction between atmosphere and hydrosphere
Composition of the atmosphere
• 78% nitrogen and 21% oxygen
• Other elements make up < 1%
• Air is never completely dry and water can be
up to 4% of its volume.
• Residence time of water vapor in the
atmosphere is ~10 days.
• Interaction with water cycle/hydrosphere
Atmospheric circulation
• Powered by sunlight
• About 51% of incoming energy is absorbed by
Earth’s land and water
• Light penetration varies depending on the
angle of approach, the sea state and the
presence of ice or other covering (e.g., foam)
• Affects planetary heat balance
Heat budget
• Energy imbalance – more energy comes in at the
equator than at the poles
• 51% of the short-wave radiation (light) striking land
is converted to longer-wave radiation (heat) and
transferred into the atmosphere by conduction,
radiation and evaporation.
• Eventually, atmosphere, land and ocean radiate heat
back to space as long-wave radiation (heat)
• Input and outflow of heat comprise the earth’s heat
budget
• We assume thermal equilibrium (Earth is not getting
warmer or cooler) or the overall heat budget of the
earth is balanced
Incoming radiation
• 16% of incoming solar radiation absorbed by
dust
• 3% absorbed by clouds
• 51% absorbed by earth
• 6% backscattered by air (leaves atm)
• 20% reflected by clouds (leaves atm)
• 4% reflected by earth’s surface (leaves atm)
Outgoing radiation
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38% emission by water and CO2 (leaves atm)
26% emission by clouds (leaves atm)
6% surface emission
30% that was reflected or scattered
Of that absorbed by earth
• 21% radiated
– 15% is absorbed by water and CO2 (greenhouse
effect)
– 6% leaves the atmosphere
• 7% conductive transfer from ground to air
• 23% evaporation
Earth’s heat budget and sun
• Earth is a closed system (essentially) wrt
mass but not energy
• Solar luminosity changes (increases over
time due to nuclear reactions within the sun)
• Greenhouse gases alter heat loss from
planet
Inputs
Exports
Concentration
Pool Size
Maintained
Inputs
Exports
Concentration
Accumulates
Inputs
Exports
Concentration
Declines
Fluxes through reservoirs – relative sizes and residence time is important
Simplified C cycle
Sources and sinks
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Fossil fuel burning
Industry & auto
Other
Biomass burning
Climate feedbacks
• Terrestrial C sinks
– Agriculture
– Forestry
• Oceanic C sinks
– Sinking C
– Burying C
• Atmospheric reactions
*Think about time scales of processes
Estimated size of C reservoirs
(Billions of metric tons)
• Atmosphere
• Soil organic matter
• Ocean
• Marine sediments &
sedimentary rocks
• Terrestrial plants
• Fossil fuel deposits
• 578 (as of 1700) to
766 (in 1999)
• 1500 to 1600
• 38,000 to 40,000
• 66,000,000 to
100,000,000
• 540 to 610
• 4000
Controls of CO2 in the ocean
• Carbonate equilibria/speciation
– Carbonate precipitation/dissolution
• Global circulation
– Solar heating and upwelling of CO2-rich water
• Photosynthesis and biosynthesis of carbonate
6CO2(g) + 6H2O hv C6H12O6 + 6O2 (g)
• Oxidation of organic matter
• Bacterial respiration
Important Concepts affecting the
ocean C cycle
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Temperature and gas solubility
Temperature and biology
Physical stratification
New production vs. recycled or regenerated
production
• Biological Pump
Projections and uncertainties
• Biota – geographical ranges and timing of spring
blooms
• Water cycle
• Ocean circulation
• Global heat budget
• Clouds
• Ocean ventilation
• Sea level rise – ice and thermal expansion
Global change on long timescales
Timescales of disturbances
• Mass extinctions
– K-T
– Permian-Triassic
• Mass extinctions
– Reradiation
– Past and future can look very different (mesozoic
mammals)
• Evolution – natural selection and biodiversity
• Adaptation versus evolution
• Rates of change within a disturbance important
– Sealevel rise and wetlands
Dinosaurs - popular
Mass extinction events
“recycling” of crustal and
oceanic materials
“uni-directional” change of
the crust and oceans
Less known but
massive
Origin of the Earth
• How old is earth and why should we
believe it (dating of a variety of things)
• Geological history – Hadean and Archean…
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400,000
Years before present
Vostok ice core records
Glacial pCO2 minima ~180 ppm
K-T Boundary
• Rare earth element
Iridium spike
• Meteorite
• 65 million years ago
• Fossil record
Permian-Triassic Mass Extinction
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Circa 251 million years before present
85% of terrestrial species extinct
95% of marine species extinct
Related to CO2
Volcanic eruptions of greenhouse gases
Acid rain, thinning ozone, and warming
Slow circulation, stagnation, low oxygen,
hydrogen sulfide production
Gaia
• Earth as an “organism”
• Life responds to physical forcing with
counteracting forces that stabilize the planet
• Earth is alive
People equal C and N
People = Nutrients
• Quite literally: 14 kg N (31
lbs) and 1.1 kg P (2.4 lbs)
per person per year
• 128 gals of sewage per
person per day
• 2.5 kg of garbage per person
per day
• Atmospheric N = 10-40% of
N load, VMT increasing at 4
times population
A Nighttime View of the Earth
-distribution of people and land
OVERVIEW
• Public policy process has become increasingly
important to academic research.
• Science and Engineering community have not
been involved with the public policy process
in proportion to its importance to the community.
• Interactions between science and policy realms
serve both, but require knowledge of each other’s
processes.
• Interactions can take as much or as little time as
scientists are willing to undertake
THE CHALLENGE
Scientific advance is a necessary but not
sufficient condition for social progress
Science must be mediated through other social
institutions (social, economic, and political) before
social progress can occur.
The gap between the “Two Cultures” must be
bridged
• C.P. Snow’s 1959 Reade Lecture alleged that social
progress was hindered by the communications gap
between science and the humanities
RELATIONSHIP BETWEEN PUBLIC AWARENESS AND
POLITICAL ACTION OVER TIME
Public Awareness
Political Action
Political Interest
Public Interest
Media Interest
Advocacy Group Interest
Scientific Interest
Time
CLIMATE CHANGE
NUCLEAR CONFLICT
Globe
International Treaty
OVER FISHING/
COLLAPSE
State Law
Nation
State/Province
Scale of Impact
National Law
Mode of Remedy
Region
ACID RAIN – LAKE EFFECTS
AUTOMOBILE
AIR POLLUTION
CHERNOBYL
Local Ordinance
Community
BOPHAL ACCIDENT
Individual/
OCCUPATIONAL
CANCER
Group Action
Individual
Time of Impact
Day
ENVIRONMENTAL EVENTS:
SCALE, TIME, AND REMEDY
Acute
Week
Month
Year
Effect
Congressional Term(s)
Presidential Term(s)
Decade
Century
Chronic