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$$$1.00$$$ to Alex p.37, exercise 1.6 (a)
“globally averaged surface pressure is 16 hPa
lower than globally averaged sea-level pressure
of 1013 hPa”
p. 11, exercise 1.1 states,
Globally averaged surface pressure is 985 hPa
Renee
Alex
Patrick
Mehmet
Andrew
Ocean structure definitions
The Carbon Cycle:
Water cycle -> phase changes
Carbon cycle -> chemical changes
Why do we care ?
Regulates 2 important greenhouse gases:
Carbon dioxide CO2, and methane CH4
Units in kg m-2
12 years
6,500 yrs
200,000 yrs
Increased evidence of human impact: Greenhouse Warming
Carbon Dioxide
Monthly-mean C02 concentrations, 1958-2002
Carbon Dioxide increase only 1/2 of that predicted
From fossil fuel consumption and forest burning
Monthly-mean C02 concentrations, 1958-2002
Where is the missing carbon ?
Units in gigatons of carbon
or Gt C
Oceans appear to uptake more than they expend.
Carbon Exchange:
CO2 + H2O -> CH2O + O2
CH2O + O2 -> CO2 + H2O
Rxn uses visible
photosynthesis Light wavelengths
Of 0.43 (blue) and
respiration
0.66 (orange)
Micron. Plants
Reflective in
Near-IR
Euphotic zone takes up carbon dioxide, decaying matter
Sinks it deeper.
Carbon in the Oceans:
1. CO2 + H2O -> H2CO3 carbonic acid
2. H2CO3 -> H+ + HCO3 bicarbonate ion
3. HCO3 -> H+ + CO32Net: CO2 + CO32- + H2O -> 2HCO3
This is connected to Calcium from the Earth’s mantle:
Ca + 2HCO3 -> CaCO3 + H2CO3 coral
Where the Ca derived from the weathering of
Rocks containing Ca-Si.
Sedimentation,Weathering,Metamorphosis
Weathering increases with temperature
Oxygen:
Unique component of Earth’s atmosphere
Increasing with time:
Photosynthesis creates oxygen
- and Reduction of water (H2O -> H2 + O) via mineralization,
with hydrogen escaping to space.
Oxygen in carbonates estimated from carbon mass.
Early Earth’s History, in brief:
1. ~ 4.5 billion years ago (bya): accretion from
planetesimals, evidence is lack of noble gases relative
to cosmos.
2. 1st ~750 millions years, named Hadean Epoch: more
bombardment, early atmosphere, moon
3. 1st production of O2, 3.0-3.8 bya.
Low atmos. conc., but ozone layer
4. Increased O2, 2 bya. -> 1st glaciation
Sudbury
K-T extinction
-> nuclear winter
Shatter cones
Sun’s luminosity increases w/ time as core contracts.
Why wasn’t Earth’s surface frozen ?
3 major glaciations. First is ~ 2.3 bya
Initial high methane conc. gives way to oxygen ->
2nd glaciation: ~ 2.5 million years ago.
•Reduced plate tectonics -> reduced volcanic
emission of CO2. +
•Increased sink of CO2 in oceans through increased
Atmospheric carbon
•Movement of Antarctica to SP -> increased albedo
• Drake Passage opens, Panama Isthmus closes
-> Changing thermohaline circulation
-> less poleward heat transport ->colder Arctic
e™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
3rd glaciation, within last million years
Antarctica ice core
Temperature, CO2, CH4 vary coherently.
Decrease is quick, rise less rapid
QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
Last glacial maximum 20,000 years ago
Global sea level ~ 125 m lower
CO2 levels ~ 180 ppm
Snow/ice extent preceeds CO2 changes
QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
Venus
Hot:
No oceans:
No hydrogen or water
Atmosphere all carbon
“runaway greenhouse
Effect”
QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
Mars
Cold & small:
No (liquid) water
No vulcanism
No atmosphere
Jupiter
WHY LIFE ON EARTH ?
ROLE OF OCEANS:
ROLE OF CHEMICAL PHYSICS:
ROLE OF TECTONICS
ROLE OF OTHER PLANETS: