The fate of pelagic CaCO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; production in a high CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; ocean: a model study

Gehlen, Marion; Gangstø, R.; Schneider, Birgit; Bopp, Laurent; Aumont, Olivier; Éthé, Christian

doi:10.5194/bg-4-505-2007

Cited by 132 publications

(145 citation statements)

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“…1a). Some of this spread is due to methodological differences, as three of the studies use varying CO 2 emissions scenarios while Gehlen et al (2007) take a different approach entirely and prescribe an atmospheric pCO 2 trajectory. Making the model comparison at a single point in time (year 2100) means that atmospheric pCO 2 differs somewhat between the models.…”

Section: Global Carbon Cycle Impacts Of Ocean Acidification In Modelsmentioning

confidence: 99%

“…The strength of the relationship between CaCO 3 :POC and [CO 2(aq) ] was taken directly from the E. huxleyi carbonate chemistry manipulation response reported by Zondervan et al (2001). Gehlen et al (2007), in the ocean GCM/biogeochemical model OCM-PISCES (Gehlen et al, 2006), generalized their parameterization of the CO 2 -calcification response by including the newly available results of mesocosm experiments (Delille et al, 2005) in addition to laboratory manipulations (Zondervan et al, 2002). For the form of the empirical fit to the observed data, Gehlen et al (2007) assumed a hyperbolic function for their parameterization, akin to the Monod equation relating phytoplankton growth to nutrient concentrations:…”

Section: Global Carbon Cycle Impacts Of Ocean Acidification In Modelsmentioning

confidence: 99%

“…Changes in the production of biogenic CaCO 3 minerals at the ocean surface could potentially also affect the transport of particulate organic carbon (POC) to depth (Armstrong et al, 2002;Klaas and Archer, 2002) and act to increase atmospheric CO 2 via a reduction in the efficiency of the biological pump. Global carbon cycle models used for projecting future global carbon cycle changes must account for observed phenomena and base their parameterizations for calcification closely on such results (e.g., Gehlen et al, 2007;Heinze, 2004;Hofmann and Schellnhuber, 2009;Ridgwell et al, 2007a, b), and these model predictions will be unreliable if rooted in unrepresentative or misunderstood laboratory observations. In addition to potential calcification impacts, higher ambient concentrations of dissolved CO 2 and acidification have been observed in the laboratory to result in a greater production of organic matter per cell in phytoplankton (Riebesell et al, 2007;Bellerby et al, 2007;Zondervan et al, 2002).…”

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confidence: 99%

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From laboratory manipulations to Earth system models: scaling calcification impacts of ocean acidification

et al. 2009

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Abstract. The observed variation in the calcification responses of coccolithophores to changes in carbonate chemistry paints a highly incoherent picture, particularly for the most commonly cultured "species", Emiliania huxleyi. The disparity between magnitude and potentially even sign of the calcification change under simulated end-of-century ocean surface chemical changes (higher pCO 2 , lower pH and carbonate saturation), raises challenges to quantifying future carbon cycle impacts and feedbacks because it introduces significant uncertainty in parameterizations used for global models. Here we compile the results of coccolithophore carbonate chemistry manipulation experiments and review how ocean carbon cycle models have attempted to bridge the gap from experiments to global impacts. Although we can rule out methodological differences in how carbonate chemistry is altered as introducing an experimental bias, the absence of a consistent calcification response implies that model parameterizations based on small and differing subsets of experimental observations will lead to varying estimates for the global carbon cycle impacts of ocean acidification. We highlight two pertinent observations that might help: (1) the degree of coccolith calcification varies substantially, both between species and within species across different genotypes, and (2) the calcification response across mesocosm and shipboard incubations has so-far been found to be relatively consistent. By analogy to descriptions of plankton growth rate vs. temperature, such as the "Eppley curve", Correspondence to: A. Ridgwell (andy@seao2.org) which seek to encapsulate the net community response via progressive assemblage change rather than the response of any single species, we posit that progressive future ocean acidification may drive a transition in dominance from more to less heavily calcified coccolithophores. Assemblage shift may be more important to integrated community calcification response than species-specific response, highlighting the importance of whole community manipulation experiments to models in the absence of a complete physiological understanding of the underlying calcification process. However, on a century time-scale, regardless of the parameterization adopted, the atmospheric pCO 2 impact of ocean acidification is minor compared to other global carbon cycle feedbacks.

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Section: Global Carbon Cycle Impacts Of Ocean Acidification In Modelsmentioning

confidence: 99%

Section: Global Carbon Cycle Impacts Of Ocean Acidification In Modelsmentioning

confidence: 99%

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confidence: 99%

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From laboratory manipulations to Earth system models: scaling calcification impacts of ocean acidification

et al. 2009

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“…Therefore TA is often used as a data constraint in global CaCO 3 modelling (e.g. Gehlen et al, 2007;Ilyina et al, 2009;Ridgwell et al, 2007). A major concern, however, in using TA concentrations for data-based model evaluation is the fact that it has a large background.…”

Section: Ta Distribution and Caco 3 Transformationsmentioning

confidence: 99%

Methods to evaluate CaCO<sub>3</sub> cycle modules in coupled global biogeochemical ocean models

et al. 2014

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Abstract. The marine CaCO 3 cycle is an important component of the oceanic carbon system and directly affects the cycling of natural and the uptake of anthropogenic carbon. In numerical models of the marine carbon cycle, the CaCO 3 cycle component is often evaluated against the observed distribution of alkalinity. Alkalinity varies in response to the formation and remineralization of CaCO 3 and organic matter. However, it also has a large conservative component, which may strongly be affected by a deficient representation of ocean physics (circulation, evaporation, and precipitation) in models. Here we apply a global ocean biogeochemical model run into preindustrial steady state featuring a number of idealized tracers, explicitly capturing the model's CaCO 3 dissolution, organic matter remineralization, and various preformed properties (alkalinity, oxygen, phosphate). We compare the suitability of a variety of measures related to the CaCO 3 cycle, including alkalinity (TA), potential alkalinity and TA * , the latter being a measure of the time-integrated imprint of CaCO 3 dissolution in the ocean. TA * can be diagnosed from any data set of TA, temperature, salinity, oxygen and phosphate. We demonstrate the sensitivity of total and potential alkalinity to the differences in model and ocean physics, which disqualifies them as accurate measures of biogeochemical processes. We show that an explicit treatment of preformed alkalinity (TA 0 ) is necessary and possible. In our model simulations we implement explicit model tracers of TA 0 and TA * . We find that the difference between modelled true TA * and diagnosed TA * was below 10 % (25 %) in 73 % (81 %) of the ocean's volume. In the Pacific (and Indian) Oceans the RMSE of A * is below 3 (4) mmol TA m −3 , even when using a global rather than regional algorithms to estimate preformed alkalinity. Errors in the Atlantic Ocean are significantly larger and potential improvements of TA 0 estimation are discussed. Applying the TA * approach to the output of three state-of-the-art ocean carbon cycle models, we demonstrate the advantage of explicitly taking preformed alkalinity into account for separating the effects of biogeochemical processes and circulation on the distribution of alkalinity. In particular, we suggest to use the TA * approach for CaCO 3 cycle model evaluation.

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“…The proportion of calcifying phytoplankton is parametrized following the formulation of Moore et al (2002), because PISCES does not prognostically represent this phytoplankton functional type. One the other hand, the dissolution rate of calcite follows the parametrization of Gehlen et al (2007): there is no dissolution is allowed when waters are supersaturated, but dissolution increases with the level of under-saturation. Total alkalinity in PISCES includes contributions from carbonate, bicarbonate, borate, hydrogen, and hydroxide ions (Practical alkalinity).…”

Section: Marine Biogeochemistry Model: Piscesmentioning

confidence: 99%

Skill assessment of three earth system models with common marine biogeochemistry

et al. 2012

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We have assessed the ability of a common ocean biogeochemical model, PISCES, to match relevant modern data fields across a range of ocean circulation fields from three distinct Earth system models: IPSL-CM4-LOOP, IPSL-CM5A-LR and CNRM-CM5.1. The first of these Earth system models has contributed to the IPCC 4th assessment report, while the latter two are contributing to the ongoing IPCC 5th assessment report. These models differ with respect to their atmospheric component, ocean subgrid-scale physics and resolution. The simulated vertical distribution of biogeochemical tracers suffer from biases in ocean circulation and a poor representation of the sinking fluxes of matter. Nevertheless, differences between upper and deep ocean model skills significantly point to changes in the underlying model representations of ocean circulation. IPSL-CM5A-LR and CNRM-CM5.1 poorly represent deep-ocean circulation compared to IPSL-CM4-LOOP degrading the vertical distribution of biogeochemical tracers. However, their representations of surface wind, wind stress, mixed-layer depth and geostrophic circulations (e.g., Antarctic Circumpolar Current) have been improved compared to IPSL-CM4-LOOP. These improvements result in a better representation of large-scale structure of biogeochemical fields in the upper ocean. In particular, a deepening of 20-40 m of the summer mixed-layer depth allows to capture the 0-0.5 lgChl L -1 concentrations class of surface chlorophyll in the Southern Ocean. Further improvements in the representation of the ocean mixedlayer and deep-ocean ventilation are needed for the next generations of models development to better simulate marine biogeochemistry. In order to better constrain ocean dynamics, we suggest that biogeochemical or passive tracer modules should be used routinely for both model development and model intercomparisons.

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The fate of pelagic CaCO<sub>3</sub> production in a high CO<sub>2</sub> ocean: a model study

Cited by 132 publications

References 64 publications

From laboratory manipulations to Earth system models: scaling calcification impacts of ocean acidification

From laboratory manipulations to Earth system models: scaling calcification impacts of ocean acidification

Methods to evaluate CaCO<sub>3</sub> cycle modules in coupled global biogeochemical ocean models

Skill assessment of three earth system models with common marine biogeochemistry

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The fate of pelagic CaCO&lt;sub&gt;3&lt;/sub&gt; production in a high CO&lt;sub&gt;2&lt;/sub&gt; ocean: a model study

Cited by 132 publications

References 64 publications

From laboratory manipulations to Earth system models: scaling calcification impacts of ocean acidification

From laboratory manipulations to Earth system models: scaling calcification impacts of ocean acidification

Methods to evaluate CaCO&lt;sub&gt;3&lt;/sub&gt; cycle modules in coupled global biogeochemical ocean models

Skill assessment of three earth system models with common marine biogeochemistry

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Product

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The fate of pelagic CaCO<sub>3</sub> production in a high CO<sub>2</sub> ocean: a model study

Methods to evaluate CaCO<sub>3</sub> cycle modules in coupled global biogeochemical ocean models