The Short-term Atmospheric Carbon Budget

1. The Short-term Atmospheric Carbon Budget • Sources • Sinks • Feedbacks

2. Questions • How are carbon reservoirs altered as their flux of material changes? • Which reservoirs and processes are important to the recycling of carbon? • Do/which feedback mechanisms regulate the amount of atmospheric CO2? • How do all of these changes impact organisms that rely on the nutrients these cycles provide?

3. Types of Carbon Cycles • Terrestrial Organic Carbon Cycle • Marine Organic Carbon Cycle • Inorganic Carbon Cycle

4. Sources of Carbon • Volcanism • Tectonic Activity • Respiration • Fossil Fuels or Combustion • Chemical Weathering (Carbonate) • Ocean Outgassing • Plant Decomposition

5. Sinks of Carbon • Photosynthetic Organisms • Atmosphere • Ocean • Burial • Silicate Weathering • Terrestrial Biomass • Sedimentary Rocks

6. Reservoirs Atm CH4 5Gt(C) Living Biomass 600 Gt(C) 1 Gt= 1 Petagram=1 Billion Metric Tons 1 Metric Ton= 1000kg Atm CO2 760 Gt(C) Oceanic dissolved CO2 740 Gt(C) Oceanic Carbonate Ion 1300 Gt(C) Organic Carbon in soils/sediments 1600 Gt(C) Marine Carbonate Sediments 2500 Gt(C) Fossil Fuels 4700 Gt(C) Oceanic Bicarbonate Ion 37000 Gt(C) Organic Carbon in Sedimentary Rocks 10,000,000 Gt(C) Limestone in Sedimentary Rocks 40,000,000 Gt(C)

7. The Carbon Cycle

8. Methods of Measurement • O2 levels in atmosphere • Surface ocean CO2 data • Subsurface dissolved inorganic carbon data • Atmospheric/Ocean 12C/13C data • Inverse atmospheric transport models • Ocean carbon models • (Manning et al)

9. Key Processes • Negative feedback relationship between Atm CO2 and plant photosynthesis • Residence Time= (Reservoir size at steady state)/Inflow rate or outflow rate • Ex: (760 Gt(C))/(60 Gt(C)/Yr)= 12.7 yrs for Atm(C) • Characteristic Response Time= when a system is not in a steady state Photosynthetic Rate Atmospheric CO2

10. Main Carbon Categories • Oxidized Carbon (combined with oxygen) • CO2, Organisms, Rust • Reduced Carbon (Organic carbon) • Combined mainly with other carbon atoms, hydrogen or nitrogen • Terrestrially dominated • Organic/Terrestrial/Marine/Geologic Processes

11. Terrestrial Organic Carbon Cycle • Photosynthesis/Respiration/Decomposition • Key Step in Cycle: • Conversion of inorganic (atmospheric CO2) to organic carbon through photosynthesis via the stomata • C3 (85%) vs C4 (5%, drought and low-light tolerant) vs CAM (Arid climates, absorption during day, conversion at night) • Residence time of many decades

12. Marine Organic Carbon Cycle • Phytoplankton (Upper 100m in water column: (Photic Zone) • Diatoms • Coccolithophorids • Zooplankton • Radiolarians • Foraminifera • Redfield Ratios: 106(C):16(N):1(Ph) reflect elemental composition of ocean in phytoplankton • “Only .1% of organic matter that settles from surface ocean is preserved in marine sediments” (Kump et. al)

14. Biological Pump

15. Inorganic Carbon Cycle • Reservoirs • Atmosphere • Ocean • Sediments • Sedimentary Rocks (Limestone, Dolomite, Wollastonite) • CaCO3 CaMg(CO3)2 CaSiO3 • Carbonic Acid: CO2 + H2O  H2CO3- • CO2 + CO3^2- +H2O  2HCO3- • Ability of carbon uptake in ocean is decreased with an increase of atmospheric CO2 because of relationship between CO2 dissolution, carbonic acid formation, carbonic acid dissolution, bicarbonate/hydrogen ion formation, decreased ph, hydrogen reaction with carbonate ion, forming another bicarbonate ion.

16. Photosynthsis OCN O2 Respiration/Combustion O2 Change Deforestation Current Levels CO2

17. What Did That Mean? • We know how much carbon we put in the Atm • We know how the carbon mixing ratio changes • We know how the oxygen mixing ratio changes • As Leonard says: “Everything has to go somewhere” • So where is it going? How is it getting there? What implications might it have? • Rates/Fluxes/Projections • (Zan, 2013)

18. Some Rates and Estimates • CO2 input to the Atm/yr= 8 petagrams/Gt (Stine,2013) • Atm Carbon in 2100: 550,700,850 • CO2 ocean turnover time is high in the surface and low in the deep: 80-1000 yrs(Kump et al) • Surface ocean pH estimated to have dropped .1 unit-log scale-30% increase in H+. Only will increase.

19. Inorganic Carbon Cycle Atm CO2 weathering Air/Sea exchange = Deep Ocean CO2 Upper Ocean CO2 Dissolution/Precipitation Marine Carbonate Sediments Carbonate Weathering Sedimentation Volcanism Carbonate Sedimentary Rocks

20. How reliable is past data? How significant would small errors be in past data? Since temperature averages and CO2 levels have essentially mirrored each other throughout history; can we expect a giant increase in temperature soon?

22. Summary • Strong coupling between Ocean Atmosphere and Biomass • Many Sources and Many Sinks • Residence times are highly variable • Carbon fluctuates between organic and inorganic • Organic matter is normally recycled quickly but can be buried in terrestrial sedimentary basins or the sea floor • Atm CO2 dissolves into rainwater • CO2 absorbs IR strongest at 15 micrometers which overlaps H2O and is a wavelength emitted strongly by Earth • Increase in CO2 could possible increase primary production and thus increase biomass and could also lead to a change in the types of plants due to their various types of photosynthesis Ts Green house Atm CO2

23. Sources Cited • Kump, Lee R., James F. Kasting, and Robert G. Crane. The Earth System. Upper Saddle River, NJ: Pearson Prentice Hall, 2004. Print • Manning, Andrew C., and Ralph F. Keeling. "Global Oceanic and Land Biotic Carbon Sinks from the." Scripps Institution of Oceanography (2006): 95-116. Print. • "The Carbon Cycle: Sources and Sinks." The Carbon Cycle: Sources and Sinks. NOAA, n.d. Web. 17 Dec. 2013. • Stine, Alexander. Personal Communication. San Francisco StateUniversity, San Francisco. 2013. Lecture.