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THE CARBON CYCLE
1. Introduction: The story so far…..
2. Inputs, outputs and stores
2. Biochemical and geochemical processes
3. Where does it all go?
4. Feedbacks in the carbon cycle
Atmosphere
EARTH
Absorption ~69%
Reflection ~31%
Solar radiation (SW)
EARTH WARMS UP- temperature > 0 Kelvin
Terrestrial radiation (LW)
ATMOSPHERE WARMS UP
Radiation to space (LW)
Radiation back to Earth (LW)
Satellite measurement of Earth’s emission spectrum. Source: NASA Goddard Space Flight Center.
Emission spectrum from Earth measured by NIMBUS-7 satellite, 1970.
Source: Hanel, 1971.
400 600 800 1000 1200 1400 0
50
100
150
220 K
240 K
260 K
280 K
300 K
320 K
Wave number (cm-1)
Rad
ian
ce
(mW
.m-2
.sr-1
cm)
H2O CO2 Atmospheric
window
O3 CH4 H2O
EARTH: THE GOLDILOCKS PLANET
Too hot Too cold Just right
ATMOSPHERE
BIOSPHERE
LITHOSPHERE
HYDROSPHERE
The carbon cycle. Source: Mann and Kump, 2009, p. 95.
The global carbon cycle. Source: Rohli and Vega, 2008, p. 16.
OXIDIZED REDUCED vs.
CO2 CH4 Carbon dioxide Methane
CARBON TERMINOLOGY
See Archer, 2012, start of chapter 8.
Photosynthesis allows green plants to make sugar:
6 CO2 + 6 H2O + sunlight glucose
PHOTOSYNTHESIS
C6H12O6 + 6 O2
Atmospheric carbon dioxide concentration recorded at Mauna Loa, Hawaii. Source: NOAA; see also Houghton, 2009, p. 41.
Phytoplankton bloom in the Atlantic Ocean, June 6, 2006, imaged by Envisat. Source: Houghton,
2009, p. 42.
C6H12O6 + 6 O2 glucose
RESPIRATION
6 CO2 + 6 H2O + energy
Respiration allows plants (and animals) to burn sugars for energy:
6 CO2 + 6 H2O + sunlight glucose
C6H12O6 + 6 O2
1991 eruption of Mt. Pinatubo, Phillipines. Source: USGS
Chemical weathering of rocks: an atmosphere-lithosphere carbon exchange
H2O + CO2 H2CO3 Mild carbonic acid
H2CO3 + CaSiO3
Calcium carbonate Wollastonite (a silicate mineral)
Hydrolysis: an example of chemical weathering
CaCO3 + SiO2 + H2O
Calcium carbonate is used to build sea shells, coral reefs, skeletons, etc. Source: DHD Multimedia Gallery, http://gallery.hd.org/_c/natural-science/sea-shells-on-sand-AHD.jpg.html
Microscope images of plankton.
Source: Kasting, et al.,1999; see also Ruddiman, 2001, p. 67.
The White Cliffs of Dover, UK– chalk, skeletons of wee beasties
Source: http://madmikesamerica.com/2010/08/the-white-cliffs-of-dover/
The carbon cycle. Source: Mann and Kump, 2009, p. 95.
Magnitudes of flows and stores in the global carbon cycle.
Source: Archer, 2012, p. 92.
ATMOSPHERE
BIOSPHERE
LITHOSPHERE
HYDROSPHERE
Magnitudes of flows and stores in the global carbon cycle.
Source: Archer, 2012, p. 92.
Magnitudes of flows and stores in the global carbon cycle.
Source: Archer, 2012, p. 92.
OCEANS LAND
ATMOSPHERE
SEDIMENTARY ROCKS
OCEANS
ATMOSPHERE
LAND
Carbon reservoirs in the global carbon cycle.
Atmosphere = 100 Land = 330 Oceans = 5132 Source: Houghton, 2009, p. 36
ATMOSPHERE
OCEAN
~4900 m deep water
~100 m mixed layer
3-D visualization of the oceans. Source: Mann and Kump, 2009, p. 60.
ATMOSPHERE
OCEAN
~4900 m deep water
~100 m mixed layer Equilibrium at 10:1
Mixing with deep water over 102 to 103 years
The solubility pump in the oceans
Microscope images of plankton.
Source: Kasting, et al.,1999; see also Ruddiman, 2001, p. 67.
ATMOSPHERE
OCEAN
~4900 m deep water
~100 m mixed layer Wee beasties soak up carbon
Bodies, shells and skeletons sink to ocean floor
The biological pump in the oceans
FEEDBACKS IN THE CARBON CYCLE
Positive? Negative?
