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Marta Álvarez Rodríguez

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Asignatura 2.07 Impacto del cambio global en los ciclos del N, P, C y metales. CARBON production during the Antropocene: sinks, sources and ocean storage. Anthropogenic carbon in the ocean. Marta Álvarez Rodríguez. IMEDEA, CSIC-UIB Esporles, Mallorca. Palma de Mallorca, February 2010. - PowerPoint PPT Presentation

Text of Marta Álvarez Rodríguez

  • DEFINITION: within a given reservoir (ocean, land or atmosphere), the excess is the increase in carbon compared to its the stock during preindustrial times. WHERE IS IT: everywhere, land, ocean and atmosphereWHERE can you MEASURE IT: atmosphere, and ocean (can be inferred), land is too heterogeneous.DISTRIBUTION:

  • Anthropogenic CO2 Budget 1800 to 1994a: From Marland and Boden [1997] (updated 2002)b: From Houghton [1997]c: Calculated from change in atmospheric pCO2 (1800: 284ppm; 1994: 359 ppm)d: Based on estimates of Sabine et al. [1999], Sabine et al. [2002] and Lee et al. (submitted)The ocean uptake a great part of CANT and they storage it. Thanks to them global warming is mitigatedUptake: across the air-sea interfaceStorage: accumulation in the water columnTransport: contrary to trees, oceans move!!, CANT is redistributed within the oceans

    CO2 Sources[Pg C](1) Emissions from fossil fuel and cement productiona 244(2) Net emissions from changes in land-useb110(3) Total anthropogenic emissions = (1) + (2)354Partitioning among reservoirs[Pg C](4) Storage in the atmospherec159(5) Storage in the oceand112(6) Terrestrial sinks = [(1)+(2)]-[(4)+(5)]83

  • once in the ocean the CO2 uptaken does not affect the radiactive balance of the Earth to predict the magnitude of climate change in the future within the carbon market (Kyoto) is important to know where is stored, important for policy makers we need to know the magnitude of the sinks and sources, and their variability and factors controlling them predict the future behavior of the ocean as a sink of CANT within a given emission scenario to control the effectiveness of the mitigation and control mechanisms as emission policies and sequestering mechanisms

  • Globally integrated flux: 2.2 PgC yr-1

  • Preindustrial FluxAnthropogenic Flux

  • OBJECTIVES:+ quantify the CO2 storage in the oceans + provide a global description of the CO2 variables distribution in the ocean to help the development of global carbon cycle models + characterize the transport of heat, salt and carbon in the ocean and the air-sea CO2 exchange.

  • + CANT is estimated or inferred, not measured + there are several methods, the most popular is Gruber et al. (1996), back-calculation technique (more during S1).+ the CANT signal over TIC is very low 60/2100 = 3%

  • GSS96 defined the semiconservative parameter DC*(t), it depends on the anthropogenic input, thus, the water mass age (t), and its include the air-sea desequilibrium constant with time:

    DC*(t) = CANT + DCTdis

  • To separate the anthropogenic CO2 signal from the natural variability in DIC. This requires the removal ofthe change in DIC that incurred since the water left the surface ocean due to remineralization of organic matter and dissolution of CaCO3 (DDICbio), anda concentration, DICsfc-pi , that reflects the DIC content a water parcel had at the outcrop in pre-industrial times, the equilibrium concentration plus any disequilibriumThus,DCant = DIC - DDICbio - DICsfc-pi = DIC DDICbio DIC280 - DDICdisAssumptions:natural carbon cycle has remained in steady-state

  • 44.5 5 Pg 44.8 6 Pg 20.3 3 PgIndian OceanPacific OceanAtlantic Ocean(Sabine et al, Science 2004)Inventory of CANT for year 1994 = 110 13 Pg C 15% area25% inventorio SO, south of 50S 9% inventory, equal area as NA

  • a) Lee et al. (submitted)b) Sabine et al. (2002)c) Sabine et al. (1999)

    AtlanticaInventory[Pg C]PacificbInventory[Pg C]IndiancInventory[Pg C]GlobalInventory[Pg C]Southern hemisphere19281762Northern hemisphere2817348Global47 (42%)45 (40%)20 (18%)112

  • How is CAN T uptaken ? + areas of cooling. + areas where old waters get to the surface Where is CANT stored ? where surface waters sink to intermediate and deep --- deep waters formation areas.

  • F air-sea = (Storage + TS + TN) + other terms - F air-sea is the air-sea CO2 flux in the region (positive into the region), - TS and TN respectively refer to the net transport of carbon across the southern and northern boundaries of the area (positive into the region). - The storage term (always negative) stands for the accumulation of anthropogenic CO2, - Other terms: river discharge, biological activity, etc...

  • F air-sea = (Storage + TS + TN)F air-sea = no se puede medirStorage = se puede estimar, dos maneras Transportes = se pueden calcular

  • TProp is the property transport from Vigo to Cape Farewell over the entire water column Prop the property concentration v velocity orthogonal to the section, ESENCIALrS,T,P in-situ density

  • Storage can be mathematically defined as:

  • The Mean Penetration Depth (MPD) of CANT using the formula by Broecker et al. (1979) is:where CANTz and CANTml are the CANT concentrations at any depth (z) and at the mixed layer (ml), Assuming that CANT is a conservative tracer (not affected by biology) that has reached its transient steady state (profile with a constant shape)

  • Calculated from: - the temporal change of CANT in the mixed layer.

    - the MPD can be derived from current TIC observations approximated assuming a fully CO2 equilibrated mixed layer keeping pace with the CO2 atmospheric increase.

  • Table 5.2. Mean Penetration Depth (MPD in meters, according to equation 5.9) of anthropogenic carbon (CANT, mean(standard deviation), CANT increasing rates (molm-2y-1), areas and final CANT storage rates by latitude band and basin. The storage rates for the Arctic ocean (*) and the GIN (Greenland-Iceland-Norwegian) seas (+) are also shown. The final storage rates for the Arctic-Subpolar (north of the 4x section) and Temperate (between the 4x and the 24.5N sections) regions are shown at the bottom.

    Latitude Band

    Basin

    MPD (m)

    CANT

    Increasing rate

    (molm-2y-1)

    Area

    (1012 m2)

    Storage rate

    (kmols-1)

    24.5-30N

    East

    1070(137

    0.93(0.12

    2.4

    72(9

    West

    1466(166

    1.28(0.14

    2.4

    99(11

    30-35N

    East

    1277(168

    1.11(0.15

    1.4

    49(7

    West

    1871(240

    1.63(0.21

    2.1

    109(14

    35-40N

    East

    1473(187

    1.28(0.16

    1.2

    50(6

    West

    2029(262

    1.77(0.23

    2.3

    128(17

    40-45N

    East

    1410(168

    1.23(0.15

    1.0

    40(5

    West

    2104(166

    1.83(0.14

    1.9

    110(9

    45-50N

    East

    1520(168

    1.32(0.15

    0.8

    35(4

    West

    1921(152

    1.67(0.13

    1.6

    82(7

    50-55N

    East

    1462(321

    1.27(0.28

    1.3

    53(12

    West

    1921(152

    1.67(0.13

    1.3

    70(6

    55-60N

    East

    1302(432

    1.13(0.38

    1.2

    42(14

    West

    1739(381

    1.51(0.33

    1.0

    48(11

    Final Storage rate (kmols-1)

    Arctic-Subpolar

    67.4+

    288(50

    68.7*

    152(50

    Temperate

    835(100

  • CANT kmol/s

  • Ocean Inversion method The ocean is divided into n regions

  • The inversion finds the combination of air-sea fluxes from a discrete number of ocean regions that optimally fit the observations:

    Cj = Carbon signal due to gas exchange calculated from observations at site j s i = Magnitude of the flux from region i H i,j = The modeled response of a unit flux from region i at station j, called the basis functions E = Error associated with the methodMikaloff Fletcher et al. (GBC, 2006)

  • Mikaloff Fletcher et al. (GBC, 2006)

  • Mikaloff Fletcher et al. (GBC, 2006)Figure 4. Global map of the time integrated (17651995) transport (shown above or below arrows) of anthropogenic CO2 based on the inverse flux estimates (italics) and their implied storage (bold) in Pg C. Shown are the weighted mean estimates and their weighted standard deviation.

  • Figure 5. Uptake, storage, and transport of anthropogenic CO2 in the Atlantic Ocean (Pg C yr1) based on (a) this study (weighted mean and standard deviation scaled to 1995), (b) the estimates of [lvarez et al., 2003], where the transport across 24N was taken from Rosn et al. [2003], (c) Wallace [2001], where the transport across 20S was taken from Holfort et al. [1998], and (d) Macdonald et al. [2003], where the transports across 10S and 30S were taken from Holfort et al. [1998], and the transport across 78N was taken from Lundberg and Haugan [1996]. Difficult to compare: OGCMs=>mean values, data=> no seasonal or temporal integration agreements and discrepancies OGCMs trp at 76N not robust, but Trp at more southern latitudes are quite robust and in agreement with data.

  • Air-Sea CANT uptake: total uptake 2.20.25 PgC/yr referred to 1995 greatest uptake in SO, 23% of the total flux, but high variability from models considerable uptake in the tropics reduced uptake at mid latitudes, but here is the greatest storage high uptake in regions where low CANT waters get to surface

  • CANT transport: calculated from divergence of the fluxes SO: large uptake with low storage, drives a high northward flux towards the equator, half the uptake is stored, rest transported SO: transport with SAMW and AAIW, 50% total transport from SO goes into Atlantic oc., stored in subtropics high storage at midlatitudes in SH due to transport from SO not from air-sea uptake NA: high uptake in mid and high latitudes, divergence in transports, high storage (NADW formation)

  • By taking up about a third of the total emissions, the ocean has been the largest sink for anthropogenic CO2 during the anthropocene.The Southern Ocean south of 36S constitutes one of