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Oceanic CO 2 removal options: Potential impacts and side effects

Oceanic CO 2 removal options: Potential impacts and side effects. Andreas Oschlies IFM-GEOMAR, Kiel. The Problem (?). Global Warming. (GISTEMP, Hansen et al., 2009). Possible/likely risks. Individual attribution to global warming difficult. The cause: Anthropogenic CO 2.

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Oceanic CO 2 removal options: Potential impacts and side effects

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  1. Oceanic CO2 removal options: Potential impacts and side effects Andreas Oschlies IFM-GEOMAR, Kiel

  2. The Problem (?) Global Warming (GISTEMP, Hansen et al., 2009)

  3. Possible/likely risks Individual attribution to global warming difficult

  4. The cause: Anthropogenic CO2 Atmospheric CO2 concentration rises (only about half as fast as emissions!) Charles Keeling (1928-2005)

  5. Risk assessment  IPCC Scenarios (IPCC, AR4, 2007)

  6. IPCC Scenarios & Reality (Manning et al., 2010)

  7. Projected global warming (Meinshausen et al., 2009)

  8. Challenge: halving global emissions by 2050 • reduce global emission by factor 2 • population growth by factor 2 • energy consumption at current EU-niveau: factor 5 • required reduction in individual emissions: 2 x 2 x 5 = 20 • Reaching this by transition to carbon-neutral power sources requires installation of ~1GW/day (until 2050). • (perhaps not impossible, but VERY challenging: in 2009 Germany installed ~5GW/yr, close to required 10GW/yr)

  9. Options Anthropogenic impact on the climate system Mitigation Reducing emissions requires collaboration

  10. Options Anthropogenic impact on the climate system Common welfare Mitigation Reducing emissions Adaptation requires collaboration perception of costs

  11. Options Anthropogenic impact on the climate system Climate system Common welfare Mitigation Reducing emissions Climate Engineering Adaptation requires collaboration unilateral option? perception of costs

  12. Climate Engineering (Keith, 2001)

  13. “Solar Radiation Management” Atmospheric CO2 lifetime is long CO2-Rest von 1000 GtC (Archer et al., 2009)  No short-term SRM solution without CO2-sequestration

  14. “Solar Radiation Management” Atmospheric CO2 lifetime is long CO2-Rest von 5000 GtC (Archer et al., 2009)  No short-term SRM solution without CO2-sequestration

  15. CO2-Sequestration CO2 artif. trees CO2 afforestation Fe fertilization alkalinity enhancement CO2 CO2 artificial upwelling storage reservoirs direct injection CO2 (Oschlies, 2010)

  16. CO2-Sequestration CO2 artif. trees CO2 afforestation Fe fertilization alkalinity enhancement CO2 CO2 artificial upwelling storage reservoirs direct injection CO2 (Oschlies, 2010)

  17. Afforestation • Culturally often viewed “positively” • Limited potential (space) • Restricted to growth phase • Afforesting Australia ~10% of current emissions for ~100yr • Impacts ecosystems • Competes with food production

  18. Afforestation • Forests generally darker than crop land • Particularly at high/mid latitudes in winter • Net warming or cooling?

  19. CO2-Sequestration CO2 artif. trees CO2 afforestation Fe fertilization alkalinity enhancement CO2 CO2 artificial upwelling storage reservoirs direct injection CO2 (Oschlies, 2010)

  20. “artificial trees” (courtesy Klaus Lackner) expensive (300 $ /ton CO2?), Energy intensive (net CO2-sink?) Still requires storage of CO2 (courtesy David Keith)

  21. CO2-Sequestration CO2 artif. trees CO2 afforestation Fe fertilization alkalinity enhancement CO2 CO2 artificial upwelling storage reservoirs direct injection CO2 (Oschlies, 2010)

  22. Lack of fertilization? Present-day sea-surface nitrate concentrations mmol/m3 Mean profile (Conkright et al., 1994) lack of macronutrients (e.g., NO3, PO4, Si(OH)4) lack of micronutrients (e.g., Fe)

  23. Ocean fertilisation • Macronutrients (NH4, NO3, PO4) • need 140kg NH4 to fix 1t C (+70kg PO4) • Input from land, e.g. Ocean NourishmentTM • Artificial upwelling, e.g. AtmOcean • Micronutrients (Fe) • need 10-1000g Fe to fix 1t C (Planktos, Climos)

  24. CO2-Sequestration CO2 artif. trees CO2 afforestation Fe fertilization alkalinity enhancement CO2 CO2 artificial upwelling storage reservoirs direct injection CO2 (Oschlies, 2010)

  25. Artificial upwelling CO2, O2 z Sea surface Z(mix) inorganic nutrients organic matter nutrients, CO2 pumping by surface wave-driven valves

  26. Simulated artificial upwelling potential pCO2 (in ppm) for pipes up to 1000m deep. Mean: -18ppm (might get more negative/better with time!)

  27. Simulated artificial upwelling potential pCO2 (in ppm) for pipes up to 1000m deep. Mean: -18ppm (might get more negative/better with time!) Potential: about 80 GtC over 100 years (~10% of current emissions) BUT: Small oceanic contribtion! (Oschlies et al., 2010)

  28. Side effect 1: Where is the missing C? Coc DSAT In the soils! kgC/m2 Cter Csoil

  29. Side effect 2: “irreversibility” Whenever ocean upwelling is stopped, mean temperatures soon exceed those of a world without Climate Engineering. Earth’s radiation balance:  Planet with colder surface waters stores more energy (Oschlies et al., 2010)

  30. CO2-Sequestration CO2 artif. trees CO2 afforestation Fe fertilization alkalinity enhancement CO2 CO2 artificial upwelling storage reservoirs direct injection CO2 (Oschlies, 2010)

  31. Ocean Iron Fertilization Present-day sea-surface nitrate concentrations mmol/m3 Mean profile (Conkright et al., 1994) lack of micronutrients

  32. Iron Fertilization at Sea “Give me a tanker load of iron and I will give you the next ice age” (John Martin, early 1990s)

  33. Iron Fertilization at Sea “Give me a tanker load of iron and I will give you the next ice age” (John Martin, early 1990s) SERIES, 2002 + 400 kg Fe SOIREE, 1999 removed ~ 400 t C

  34. Natural Southern Ocean Fe fertilization: Crozet Islands (Pollard et al., 2009)

  35. Simulated Southern Ocean Fe fertilization fertilized area Potential: 60 GtC over 100 years Global uptake < local CO2 flux  non-local backflux global (Oschlies et al., 2010)

  36. Possible side effect: Suboxia OIF-induced decrease in simulated suboxic volume!

  37. Possible side effect: Acidification DpH Reduced acidification in remote surface waters!

  38. More (serious?) side effects: N2O, ecology Jin & Gruber (2003): offsetting effect of enhanced N2O emissions: ca 5-20% • Ecological effects poorly understood • Ecological effects intended • Will have winners and losers

  39. CO2-Sequestration CO2 artif. trees CO2 afforestation Fe fertilization alkalinity enhancement CO2 CO2 artificial upwelling storage reservoirs direct injection CO2 (Oschlies, 2010)

  40. Dissolution of carbonate and silicate rocks Alkalinity enhancement = neutralizes carbonic acid Reduces pCO2 of surface water  enhances air-sea CO2 flux Major mining operation! Limited by ocean circulation to <1GtC/yr sequestration (to avoid oversaturation; Köhler et al., 2010) Contamination by trace metals likely.

  41. CO2-Sequestration CO2 artif. trees CO2 afforestation Fe fertilization alkalinity enhancement CO2 CO2 artificial upwelling storage reservoirs direct injection CO2 (Oschlies, 2010)

  42. Direct CO2 injection into the ocean Currently not allowed (London “Anti-dumping” convention & protocol)

  43. Direct CO2 injection into the ocean According to 3D ocean circulation models, deep injection has life times of hundreds of years. (Orr et al., 2001)

  44. Conclusions • Sequestration potential of all methods limited to about 1GtC/yr over 100 years, each. • Artificial upwelling: messes up Earth’s radiation balance • Fe fertilization: messes up ecosystem, but has natural analogs • Alkalinity enhancement: major mining operation, impurities • Direct injection has large potential but is currently considered as dumping. • Validation? • Not locally possible (if at all)

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