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Carbon in the Ocean and Climate Change

Carbon in the Ocean and Climate Change. by Dr. Douglas Vandemark University of New Hampshire, OPAL doug.vandemark@unh.edu with help from Dr. Christopher L. Sabine Pacific Marine Environmental Lab, NOAA. July 30, 2007. Carbon in the Ocean and Climate Change. Addressing three questions:

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Carbon in the Ocean and Climate Change

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  1. Carbon in the Ocean and Climate Change by Dr. Douglas Vandemark University of New Hampshire, OPAL doug.vandemark@unh.edu with help from Dr. Christopher L. SabinePacific Marine Environmental Lab, NOAA July 30, 2007

  2. Carbon in the Ocean and Climate Change • Addressing three questions: • How is the ocean’s carbon content tied to the Earth’s climate? • What do we know and not know about how carbon cycles between the ocean, land, and atmosphere? • How do we obtain data needed to help answer these questions?

  3. Carbon cycling between reservoirs

  4. Carbon in the Ocean and Climate Change • Addressing three questions: • How is the ocean’s carbon content tied to the Earth’s climate? • a) Greenhouse gas buffer - the ocean is soaking up ~35% of new CO2 via ocean-air exchange

  5. Air-sea exchange: CO2 movement between the air and sea is continuous and over time takes up fossil fuel emissions CO2 Flux = transfer_rate * ( pCO2air-pCO2sea ) CO2air CO2sea

  6. How can oceanographers help us to better understand global climate change? Source: LDEO Pre 1990s view of the global carbon cycle could not account for all the CO2 released to the atmosphere.

  7. 1 part per million in the atmosphere = 2.1 billion tons C For Carbon unit conversions see: http://www.eia.doe.gov/oiaf/1605/gg96rpt/appe.html

  8. Stephens et al., Science 2007

  9. Carbon in the Ocean and Climate Change • Addressing three questions: • How is the ocean’s carbon content tied to the Earth’s climate? • Greenhouse gas buffer • Ocean acidification - altering the ecosystem

  10. Rising atmospheric CO2 is changing the chemistry of the ocean CO2 is an acid gas so the addition of 22 million tons of carbon dioxide to the ocean every day is acidifying the seawater…we call this process “ocean acidification” CO2 + H2O H2CO3 HCO32- + H+ CO32- + H+ pH After Turley et al., 2005

  11. Coccolithophores: free floating marine algae that form the base of the food chain pCO2 780-850 ppmv pCO2 280-380 ppmv Calcification decreased - 9 to 18% Emiliania huxleyi - 45% Gephyrocapsa oceanica Manipulation of CO2 system by addition of HCl or NaOH Riebesell et al.(2000); Zondervan et al.(2001).

  12. Carbon in the Ocean and Climate Change • Addressing three questions: • How is the ocean’s carbon content tied to the Earth’s climate? • Greenhouse gas buffer • Ocean acidification - altering the ecosystem • GeoEngineering - CO2 storage in the ocean via the biological pump • see MBARI’s new Iron Fertilization site: • http://www.mbari.org/earth/Iron/iron.htm

  13. International Surface Ocean - Lower Atmosphere Study (SOLAS) Program: ocean carbon sequestration position statement May 2007 Large-scale fertilisation of the ocean is being actively promoted by various commercial organisations as a strategy to reduce atmospheric CO2 levels. However the current scientific evidence indicates that this will not significantly increase carbon transfer into the deep ocean or lower atmospheric CO2. Furthermore there may be negative impacts of iron fertilization including dissolved oxygen depletion, altered trace gas emissions that affect climate and air quality, changes in biodiversity, and decreased productivity in other oceanic regions. It is then critical and essential that robust and independent scientific verification is undertaken before large-scale fertilisation is considered. Given our present lack of knowledge, the judgement of the SOLAS SSC is that ocean fertilisation will be ineffective and potentially deleterious, and should not be used as a strategy for offsetting CO2 emissions.

  14. SOLAS carbon storage references Bakker, D. C. E., 2003, Storage of carbon dioxide by greening the oceans? In: SCOPE/GCPRapid Assessment Project. Towards CO2 stabilization: Issues, strategies and consequences.SCOPE Special Issue, Island Press. Boyd. P. W., Law, C. S., Wong, C. S., Noriji, Y., Tsuda, A., Levasseur, M., Takeda, S., et al2004, The decline and fate of an iron-induced subarctic phytoplankton bloom. Nature 428:549-553. Chisholm, S. W., Falkowski, P. G. & J. J. Cullen, 2001, Dis-Crediting Ocean Fertilization.Science 294:309-310. 12 October 2001. Gnanadesikan, A., Sarmiento, J. L. & R. D. Slater, 2003, Effects of patchy ocean fertilizationon atmospheric carbon dioxide and biological production. Global Biogeochemical Cycles,17(2), 19/1-7 doi:10.1029/2002GB001940. Jin, X. and Gruber, H., 2003, Offsetting the raidative benefit of ocean iron fertilisation byenhancing N2O emissions. Geophys. Res. Letters. 30(24): 2249- doi:10.1029/2003GL018458. Law, C. S. and R. D. Ling, 2001, Nitrous oxide fluxes in the Antarctic Circumpolar Current,and the potential response to increased iron availability. Deep-Sea Rtes. II 48(11). 2509-2528. Liss, P. S., Chuck, A., Bakker, D. and S, Turner, 2005, Ocean fertilization with iron: effects onclimate and air quality. TELLUS Series B-Chemical and Physical Meteorology 57(3): 269-271Jul 2005 Zeebe, R. E. and Archjer, D., 2005, Feasibility of ocean fertilization and its impact on futureatmospheric CO2 levels. Geophys. Res. Lett. 32, L09703, doi: 10.1029/2005GL022449,2005

  15. Carbon in the Ocean and Climate Change • Addressing three questions: • How is the ocean’s carbon content tied to the Earth’s climate? • What do we know and not know about how carbon cycles between the ocean, land, and atmosphere?

  16. Air-sea exchange: CO2 movement between the air and sea is continuous and over time takes up fossil fuel emissions CO2 Flux = transfer_rate * ( [CO2]air-[CO2]sea ) [CO2]air [CO2]sea

  17. Chemical Reactions of Carbonate Species in Seawater CO2 Atmosphere K1 K2 CO2aq (CO2 + H2O) HCO3– + H+ CO32– + H+ Ca2+ CaCO3 calcification a = [Ca2+][CO32-] Ksp’ a > 1 ~ Supersaturated CaCO3 + CO2 + H2O dissolution Ca2+ + 2HCO3-

  18. Carbon in the Ocean and Climate Change Definitions: pCO2 - the partial pressure of dissolved carbon dioxide in seawater or air. On average this is 383 ppm ( or 382 uAtm) in 2007 and on the rise. TA (total alkalinity) - seawater’s buffering capacity or its ability to neutralize H+ ions. Mainly this is an indicator of carbonate (CO3--). Water’s resistance to a change in pH. (units of uMol/kg) pH (potential of Hydrogen) - a inverse measure of H+ ion concentration to provide acidity to alkalinity measure (pH units 0-14, ocean ~ 8.05 ) Aragonite (calcium carbonate) - the most common form of CaCo3-- that precipates from seawater - it forms the skeletons of marine invertebrates.

  19. CO2SYS carbon system calculator - in EXCEL DOE ORNL/CDIAC-105 Download the CO2SYS.EXE Program Download the CO2sys_macro_PC.xls or CO2sys_macro_MAC.xls Program Download of CDIAC-105 Please Cite As: Lewis, E., and D. W. R. Wallace. 1998. Program Developed for CO2 System Calculations. ORNL/CDIAC-105. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee. Program Developed for CO2 System Calculations By Ernie Lewis1 and Doug Wallace2 1 Department of Applied ScienceBrookhaven National LaboratoryUpton, New York 2 Abteilung Meereschemie
Institut fuer Meereskunde
Duesternbrooker Weg 20
24105 Kiel, GermanyPrepared by
Linda J. Allison
Carbon Dioxide Information Analysis Center
Oak Ridge National Laboratory
Oak Ridge, Tennessee, U.S.A.


  20. BIOLOGY AND CO2 in the OCEAN the Biological Pump - a slight imbalance between…. P - Photosynthesis (phytoplankton): energy (sunlight) + 6CO2 + H2O -> C6H12O6 + 6O2 R - Respiration (bacteria, zooplankton, …): C6H12O6 (organic matter) + 6O2 -> 6CO2 + 6 H2O + energy The Pump = Excess Carbon (particles) that fall to the deep HOW DOES THIS PUMP WORK? WHERE? and WILL IT CHANGE GREATLY IN THE FUTURE?

  21. Ocean mixing - the Solubility Pump After Broecker 1991

  22. In the early 1990s we conducted a global survey of CO2 in the oceans to determine how much fossil fuel is stored in the ocean.

  23. Column inventory of anthropogenic CO2 that has accumulated in the ocean between 1800 and 1994 (mol m-2) 40 Pg C 22 Pg C 44 Pg C Mapped Inventory 106±17 Pg C

  24. Because the ocean mixes slowly, half of the anthropogenic CO2 stored in the ocean is found in the upper 10% of the ocean. 50% of anthropogenic CO2 in the ocean is shallower than 400 m Average penetration depth 1000 m

  25. 36% 43% 29% + to - 13-23% 55-26% Sabine and Feely, 2005 First 180 years the ocean absorbed 44% of emissions Last 20 years the ocean absorbed 36% of emissions

  26. Studies have even shown that the shells of living pteropods begin to dissolve at elevated CO2 levels C. pyramidata Limacina helicina Prismatic layer (1 µm) peels back Whole shell: Clio pyramidata Arag. rods exposed Aperture (~7 µm): advanced dissolution Normal shell: unexposed to undersaturated water

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