Khatiwala, S.

Sabine, C. L.

Tanhua, Toste

English

OceanRep

Paris Sept 14, 2011Carbon Changes in the Interior OceanToste TanhuaSamar KhatiwalaChristopher L. SabineThe Anthropogenic PerturbationKhatiwala et al., 2009The ocean has absorbed ~46% of the total Fossil fuel + cement production emissionsCurrently the ocean is absorbing ~2.3 PgC/yearand the emissions is ~ 8.4 PgC/year.The ocean is currently absorbing ~25% of the emissionsFF emissions (GCP 2009)Three estimates of the global inventory of anthropogenic carbon for year1994(excluding marginal seas):•Sabine et al., 2004: 106 ± 17 PgC•Waugh et al., 2006: 94 – 121 PgC•Khatiwala et al., 2009: 114 ± 22 PgC(140 ± 25 PgC in 2008)Interior ocean anthropogenic carbonThe different estimates are all within the uncertainties. Differences are in the details. 114 ± 2294 – 121(134)106 ± 17ΔC* - GreenWaugh et al., 20006TTD - ΔC*GreenTTDΔC*Column Inventory of Cant (1990-2005 mean) [mol/m2]A vertical view of the Cant distributionRios et al., 2010Southwest Atlantic OceanThe distribution in the vertical does matter!Tanhua et al., 2010Northwest Atlantic OceanCCSMGruber et al., 2009Gruber et al., 2009Ocean inversionsGerber et al., 2009Uptake and TransportDon’t forget the Marginal SeasOlsen et al., 2010 and Tanhua et al., 2009Schneider et al., 2010Park et al., 2006The Marginal Seas add up to > 8 PgC, i.e. ~6% of the total (Lee et al., 2010)Perez et al. (2010) suggest a correlationBetween NAO and Cant storage rateNigh NAO ► high Cant storage rate0.550.752.33Steinfeldt et al. 2009 foundvariations in storage ratethat are probably linked todecadal scale fluctuations inLabrador Sea Water formation.Decadal scale variationsin circulations has the potential to bias storage rate estimates of carbon.Decreased Buffer CapacityWarmer OceanCO2 OutgassingDIC increaseCarbon Over-ConsumptionIncreased Carbon ExportAcidificationReduced CalcificationLess CO2 Released During CalcificationIncreased StratificationFavored conditions for CoccolitophoresOver DiatomsIncreased Southern Ocean WindsIncreased Overturning ? ?Denitrification ► Decreased Carbon Particle ExportNitrogen Fixation► Increased Carbon Particle ExportReduced Particle BallastLess Particle FluxExtended Oxygen Minimum ZonesIncreased Dissolution of Calcium CarbonateReduced MOCReduced Transport of Cant to the Deep OceanReduced upwellingAdapted from SabineCarbon feedbacksEnhanced recycling of OMLess nutrients available for PPChallengesThe current scientific paradigm is that anthropogenic CO2 is entering the ocean as a passive thermodynamic response to rising atmospheric CO2. The current challenge for the scientific community is to determine whether these feedbacks are occurring and how they will modify the ability of the ocean to store Cant over the next few decades.Sabine and Tanhua 2009Sabine and Tanhua 2009What is the status of observations?Time-series with carbon measurements Hydrographic sections withcarbon measurementsOcean interior carbon observationsvs. time (CARINA + GLODAP)Oxygen on ArgoJuranek et al., 2011TO2pHΩDICTAInterior carbon observationsOcean interior observations remain the best mechanism for verifying the changes in ocean Cant inventory. It is extremely difficult to predict how the many possible carbon cycle feedbacks will affectocean carbon storage; modeling and proxy techniques are limited by our current understanding of the ocean carbon cycle. It is critically important that we understand how Cant is accumulating in the ocean on time scales relevant to human civilization (years to decades). CO2 emissions are growing at an ever increasing rate and the momentum of the carbon and climate system is such that decisionsmade today will still impact the climate for hundreds to thousands of years from now. The best way to improve our understanding is to continue using abroad suite of approaches with both observations and models to examine both ocean carbon uptake and ocean carbon storage over a range of time scales.Sabine and Tanhua 2009

Carbon Changes in the Interior Ocean

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