Course definition Can’t understand planetary processes including oceanography without...
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Transcript of Course definition Can’t understand planetary processes including oceanography without...
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
• 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
• 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
Vostok ice core recordsGlacial pCO2 minima ~180 ppm change of about 100 ppm over 100,000 years 0.001 ppm/year
400,0000
Years before present
What is unnatural or due to humans (anthropogenic)
Change of ~80 ppm0.4 ppm/year
Use of fossil fuelsDeforestation
Rising atmospheric pCO2
750 – 800 ppm
2100
Ozone depletion
• Political success
• Tractable by eliminating a few chemicals (CFCs)
Atmosphere & Ocean
• Gases and water freely exchange at the ocean-atmosphere 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
• 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
ConcentrationPool Size
Maintained
Inputs Exports
ConcentrationAccumulates
Inputs Exports
ConcentrationDeclines
Inputs Exports
Fluxes through reservoirs – relative sizes and residence time is important
Simplified C cycle
Sources and sinks
• 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 C6H12O6 + 6O2 (g)
• Oxidation of organic matter• Bacterial respiration
hv
Important Concepts affecting the ocean C cycle
• 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 timescalesTimescales 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
“uni-directional” change of the crust and oceans
“recycling” of crustal and oceanic materials
Mass extinction events
Dinosaurs - popular
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…
Vostok ice core recordsGlacial pCO2 minima ~180 ppm
400,0000
Years before present
K-T Boundary
• Rare earth element Iridium spike
• Meteorite
• 65 million years ago
• Fossil record
Permian-Triassic Mass Extinction
• 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 increasinglyimportant to academic research.
• Science and Engineering community have notbeen involved with the public policy processin proportion to its importance to the community.
• Interactions between science and policy realmsserve both, but require knowledge of each other’sprocesses.
• Interactions can take as much or as little time asscientists are willing to undertake
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
THE CHALLENGE
Scientific Interest
Advocacy Group Interest
Media Interest
Political Interest
Pu
bli
c A
wa
ren
es
s
Time
RELATIONSHIP BETWEEN PUBLIC AWARENESS AND POLITICAL ACTION OVER TIME
Political Action
Public Interest
Individual
Community
Region
Nation
Globe
Day Week Month Year Decade Century
CLIMATE CHANGE
CHERNOBYL
OVER FISHING/COLLAPSE
NUCLEAR CONFLICT
BOPHAL ACCIDENT
OCCUPATIONALCANCER
AUTOMOBILE AIR POLLUTION
Acute Chronic
Congressional Term(s)
Presidential Term(s)
Effect
Local Ordinance
National Law
International Treaty
Individual/
Group Action
Sc
ale
of
Imp
ac
t
Mo
de
of
Re
me
dy
State/ProvinceState Law
ACID RAIN – LAKE EFFECTS
ENVIRONMENTAL EVENTS:
SCALE, TIME, AND REMEDY
Time of Impact