core theme 4 : biogeochemical feedbacks on the oceanic carbon sink. m. gehlen (cea/dsm/lsce)
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CarboOcean Annual Meeting Bremen 4-7/12/2007. Core Theme 4 : Biogeochemical Feedbacks on the Oceanic Carbon Sink. M. Gehlen (CEA/DSM/LSCE). Core Theme 4: Feedbacks on the Oceanic C Sink. - PowerPoint PPT PresentationTRANSCRIPT
Core Theme 4 :
Biogeochemical Feedbacks on the Oceanic Carbon Sink.
M. Gehlen (CEA/DSM/LSCE)
CarboOcean Annual Meeting Bremen 4-7/12/2007
4. Identification and understanding of biogeochemical feedback mechanisms which control marine carbon uptake and release:Operational goal: The quantitatively important feedbacks between CO2 partial pressure and other carbon cycle variables will be identified and analysed. Quantitative descriptions that can be used in models will be derived. Key regions for feedback processes will be identified and strategies to monitor the evolution of feedbacks will be developed
Delivery: Assessment of the role of biogeochemical feedbacks for oceanic CO2 uptake.
Core Theme 4: Feedbacks on the Oceanic C Sink
A comparison of anthropogenic carbon during the LOMROG 07 and IAOE 91 cruises in the Arctic Ocean
S. Jutterström, S. Hjalmarsson, L. G. Anderson, K. G. Olsson
Cruise tracks for the cruises in 1991 (IAOE-91) and 2007 (LOMROG-07). Marked in black is the section used in the study.
Core Theme 4: Feedbacks on the Oceanic C Sink
Identification of key regions: Changes in the Arctic Ocean
Core Theme 4: Feedbacks on the Oceanic C Sink
Changes in Cant (mol/kg) and CFC-11 (pmol/kg)
MLR approach after Wallace (1995)
MLR, C* (Gruber et al., 1996), TrOCA (Touratier & Goyet, 2004 a,b; Touratier et al. 2007) all yield similar results
2007
1991
Cant 2007-1991
Saturation depth () for aragonite and calcite over the section.
arag
calcite
1991 2007
Core Theme 4: Feedbacks on the Oceanic C Sink
Evidence for rapid changes in C chemistry
1.4
1.2
1.0
0.8
2.252.01.751.501.25
Core Theme 4: Feedbacks on the Oceanic C Sink
Quantitative evaluation of the pelagic calcification/dissolution feedback on atmospheric pCO2 including climate change.
D16.12 report - Schneider et al.
Pelagic calcification = calcite + aragonite
Core Theme 4: Feedbacks on the Oceanic C Sink
PI-CO2: 0 %PI+CO2: -13.1 %
CC-CO2: -9.20 %CC+CO2: -21.44 %
CC-CO2: -24.5 %CC+CO2: -44.6 %
PI-CO2: 0 %PI+CO2: -28.5 %
relative to PI-CO2
80 GtC
Core Theme 4: Feedbacks on the Oceanic C Sink
D16.12 Quantitative evaluation of the pelagic calcification dissolution
feedback on atmospheric pCO2 including climate change.
contrasting effects of warming and atmospheric pCO2 increase on future saturation state of ocean surface waters warming induced circulation changes aggravate the impact of ocean acidification on calcite and aragonite production positive feed-back of warming on air-sea exchange is likely to overcompensate the negative FB from decreasing calcification the overall magnitude of feed-back controlled by circulation changes and solubility pump
3xCO2
2xCO2
present CO2
C/N=7.9C/N=8.9
C/N=6.7
Riebesell et al. (subm.)
Core Theme 4: Feedbacks on the Oceanic C Sink
Pelagic Ecosystem CO2 Enrichment Study (PeECE)(Bergen May 10 – June 12, 2005)
Identifying and quantifying of new feed-backs: C/N = f(pCO2)
Photosynthetic C drawdown
C:N = f(pCO2)
Oschlies et al. (subm.)
projected (SRES A2)
observed• Assumption: Mesocosm results can be
extrapolated to global ocean …
• UVic Earth system model (Schmittner et al., subm.)1.8 x 3.6 degree resolution, 19 levelsNPZD + diazotrophs ecosystem,
(N,P,C,O2)
• Simulations from 1765 to 2100forced by CO2 emissions (historical+SRES
A2)
C:N=const.C:N=f(pCO2)
Core Theme 4: Feedbacks on the Oceanic C Sink
C:N=const.C:N=f(pCO2)
Export production
Oceanic carbon storage
Int(del EP)Int(del C storage)
Cumulative signal
Direct impact on marine carbon uptake: minor
Oschlies et al. (subm.)
Core Theme 4: Feedbacks on the Oceanic C Sink
Export production and C-storage
Experiment location Period no. of experiments Incubation period Depth range
OM-remineralisation Bergen, Mesocosm LSF 2005 1 100 days (12 m), in bags
POM-remineralisation Kattegat, Danish waters 2006-2007 5 x 5 stations 30 days 30 m
POM-remineralisation Atlantic, Pacific Ocean 2006-2007 9 stations 30 days 50 - 450 m
DOM-remineralisation Global Ocean 2006-2007 19 stations 100 days 30 m
Project status:Experimental studies have been completed for quantifying the effect from changes in temperature on the remineralisation rate of organic matter.Experimental results:A significant temperature effect is seen from oxygen consumption during organic matter degradation. Nitrification rates and the relative rate of C- and N-release during remineralisation is influenced by temperature.
Core Theme 4: Feedbacks on the Oceanic C Sink
Temperature dependent remineralisation of organic matter
Bendtsen et al.)
National Environmental Research Institute, Aarhus UniversityDenmark
Core Theme 4: Feedbacks on the Oceanic C Sink
Temperature sensitivity of DOM in the Global ocean
National Environmental Research Institute, Aarhus UniversityDenmark
Incubation experiments with upper ocean waters from the Atlantic, Southern Ocean andPacific ocean at 30 m depth. Oxygen consumption is measured by optodes during 100 days at three different temperatures in triplicates.
Example from north of the Azores.Oxygen consumption during 100 daysof incubation in 0.5 l bottles.
Core Theme 4: Feedbacks on the Oceanic C Sink
National Environmental Research Institute, Aarhus UniversityDenmark
Significant temperature dependence for DOM and POM remineralisation rates. A first calculation of the “overall” temperature dependence from mesocosm experiments gave a Q10 of 1.7.
A simple Q10-parameterisation is not sufficient for explaining the transient behaviour of Oxygen and DIN in the experiments.
This and more results are presented on two posters:1. Temperature dependence of remineralisation of organic matter; J. Bendtsen, T. G. Nielsen,
J. L. S. Hansen and K.M. Hilligsøe2. Influence of temperature change on remineralization rates in the world oceans. Results from
the circumnavigating Galathea 3 expedition; K. M. Hilligsøe, T. G. Nielsen, K. S. Jensen, K. Richardson, J. Bendtsen.