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Remote input of nutrients in a changing climate

Remote input of nutrients in a changing climate. Max-Planck-Institut für Meteorologie KlimaCampus, Hamburg. J. Segschneider. WP 16. CarboOcean final meeting, 5-9 October 2009, Os, Norway. Main nutrients addressed. Iron from dust input Nitrogen from agriculture and fossil fuel burning

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Remote input of nutrients in a changing climate

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  1. Remote input of nutrients in a changing climate Max-Planck-Institut für MeteorologieKlimaCampus, Hamburg J. Segschneider WP 16 CarboOcean final meeting, 5-9 October 2009, Os, Norway

  2. Main nutrients addressed Iron from dust input Nitrogen from agriculture and fossil fuel burning Nutrients from rivers + nutrients from volcanic eruptions

  3. The dust/iron cycle and climate Iron is supplied to the ocean from atmospheric dust, which in turn is mobilized from arid land surfaces. Solubility of iron in ocean water differs with distance from dust source - atmospheric chemistry- Iron is thought to be the limiting nutrient in large areas of the ocean (the Southern Ocean, equatorial Pacific, North-West Pacific) A model study shows a reduction of dust supply in a 2xCO2 climate by 30% (Mahowald et al., 2006) – does this impact on the carbon cycle?

  4. A simplified view of the marine carbon cycle 90 solubility pump 103 Plankton 92 11 42 31 biological pump Atmosphere Ocean dissolved carbon Thermocline dissolved carbon Fluxes in GtC/ Year Sediment

  5. The biological pump NO3 PO4 Fe PO4 NO3 CO2 CO2 CO2 PO4 DEPTH • pump is driven • by nutrients and • solar radiance • Redfield ratio • 1 P : 16 N NO3 PO4 NO3 CO2 Bacterial remineralisation

  6. The iron cycle Jickells et al

  7. Model test: difference in dust deposition (2xCO2 climate - present climate) Mahowald et al, 2006 on GR30 grid

  8. Difference in oceanic iron concentration (surface) (2xCO2 dust - present dust ) ocean only experiment:

  9. Change in photosynthesis Change in photosynthesis 2xCO2 minus preindustrial dust deposition as annual average [units: 10-10 kmol P /day /m3]

  10. Effect on export production 2xCO2 minus preindustrial climate dust deposition [annual average, units 10-6 gC/m2/day]

  11. CO2-Flux Difference in atmosphere to ocean net CO2 flux 2xCO2 – preindustrial dust deposition [annual average, units: 10-7 kmol/m2/day]

  12. Impact on Cant uptake Decrease in export production by ~0.4 GtC/a Around 20% of current oceanic uptake of anthropogenic carbon Not first order process but not negligible either Ongoing Research • oceanic uptake of CO2 • biological feedbacks

  13. Further processes Nitrogen from agriculture and fossil fuel burning Nutrients from rivers + nutrients from volcanic eruptions Ongoing Research • oceanic uptake of CO2 • biological feedbacks

  14. Volcanoes: Pinatubo Carbon Anomaly ~1.6 x 1015 g C(Sarmiento, 1993; Watson, 1997) Future Plans • Volcanic eruptions

  15. Do volcanic eruptions have an impact on the marine carbon cycle and a feedback on climate? can the additional ash/nutrients trigger algae blooms and additional CO2 uptake of the ocean? does reduced radiation significantly reduce biological production and hence carbon uptake, how does this impact on atmospheric pCO2? (potential for stabilizing temperature) is the physical pump affected (colder water?) Future Plans • Volcanic eruptions •

  16. N-cycle and climate change Gruber & Galloway, Nature, 2008 Future Plans • N-cycle and climate change

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