Remote input of nutrients in a changing climate J. Segschneider Max-Planck-Institut für Meteorologie KlimaCampus, Hamburg CarboOcean final meeting, 5-9 October 2009, Os, Norway WP 16
Jan 04, 2016
Remote input of nutrients in a changing climate
J. SegschneiderMax-Planck-Institut für Meteorologie
KlimaCampus, Hamburg
CarboOcean final meeting, 5-9 October 2009, Os, Norway
WP 16
Main nutrients addressed
• Iron from dust input • Nitrogen from agriculture and fossil fuel burning
• Nutrients from rivers
• + nutrients from volcanic eruptions
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?
A simplified view of the marine carbon cycle
Atmosphere
Thermocline
Ocean
Sediment
3142
90
solubility pump dissolved
carbon
Fluxesin
GtC/ Year
dissolvedcarbon
11
103
92
biologicalpump
Plankton
The biological pump
• pump is driven by nutrients and solar radiance
• Redfield ratio 1 P : 16 N
DEPTH
NO3 CO2
PO4
PO4 NO3
CO2
NO3
CO2
PO4
PO4 NO3
CO2
Bacterial remineralisation
Fe
Jickells et al
The iron cycle
Model test: difference in dust deposition
(2xCO2 climate - present climate)
Mahowald et al, 2006 on GR30 grid
Difference in oceanic iron concentration (surface)
(2xCO2 dust - present dust )
ocean only experiment:
Change in photosynthesis
Change in photosynthesis 2xCO2 minus preindustrial dust
deposition as annual average [units: 10-10 kmol P /day /m3]
Effect on export production
2xCO2 minus preindustrial climate dust deposition
[annual average, units 10-6 gC/m2/day]
CO2-Flux
Difference in atmosphere to ocean net CO2 flux
2xCO2 – preindustrial dust deposition
[annual average, units: 10-7 kmol/m2/day]
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
Further processes
• Nitrogen from agriculture and fossil fuel burning
• Nutrients from rivers
• + nutrients from volcanic eruptions
Ongoing Research • oceanic uptake of CO2 • biological feedbacks
Volcanoes: Pinatubo Carbon Anomaly
~1.6 x 1015 g C(Sarmiento, 1993; Watson, 1997)
Future Plans • Volcanic eruptions
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 •
N-cycle and climate change Gruber & Galloway, Nature, 2008
Future Plans • N-cycle and climate change