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