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Ciclo global del carbono y su perturbación antropogénica +161 1.9 Land sink 5.4 1.7 Land use change 21.9 20 -220 +65 -125 +18 1.6 +100 DEFINITION: within a given reservoir (ocean, land or atmosphere), the excess is the increase in carbon compared to it’s the stock during preindustrial times. WHERE IS IT: everywhere, land, ocean and atmosphere WHERE can you MEASURE IT: atmosphere, and ocean (can be inferred), land is too heterogeneous. DISTRIBUTION: Anthropogenic CO2 Budget 1800 to 1994 CO2 Sources [Pg C] (1) Emissions from fossil fuel and cement productiona 244 (2) Net emissions from changes in land-useb 110 (3) Total anthropogenic emissions = (1) + (2) 354 Partitioning among reservoirs [Pg C] (4) Storage in the atmospherec 159 (5) Storage in the oceand 112 The ocean uptake a great part of CANT and they storage it. Thanks to global sinks warming is mitigated (6) them Terrestrial = [(1)+(2)]-[(4)+(5)] 83 Uptake: across the air-sea interface Storage: accumulation in the water column a: From Marland andcontrary Boden [1997] Transport: to(updated trees,2002) oceans move!!, b: From Houghton [1997] CANT is redistributed within the 1994: oceans c: Calculated from change in atmospheric pCO2 (1800: 284ppm; 359 ppm) d: Based on estimates of Sabine et al. [1999], Sabine et al. [2002] and Lee et al. (submitted) - 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 Method Carbon Uptake (Pg C yr-1) Reference Measurements of sea-air pCO2 Difference 2.1 ± 0.5 Takahashi et al. [2002] Inversion of atmospheric CO2 observations 1.8 ± 1.0 Gurney et al. [2002] Inversions of ocean transport models and observed DIC 2.0 ± 0.4 Gloor et al. [2003] Model simulations evaluated with CFC’s and pre-bomb C-14 2.2 ± 0.4 Matsumoto et al. [2004] 2.38 ± 0.28 Orr et a.l [2004] OCMIP-2 Model simulations Based on measured atm. O2 and CO2 inventories corrected for ocean warming and strat. GCM Model of Ocean Carbon CFC ages Keeling & Manning [submitted] 2.2 ± 0.5 1.93 Wetzel et al. (2005) 2.0 ± 0.4 McNeil et al. (2003) Fluxes are normalized to 1990-1999 (except Keeling & Manning which is for 1993-2004) and corrected for pre-industrial degassing flux of ~0.6 Pg C yr–1. Globally integrated flux: 2.2 PgC yr-1 Preindustrial Flux Anthropogenic Flux WOCE/JGOFS/OACES Global CO2 Survey 1991-1997 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% GSS’96 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 of i) the change in DIC that incurred since the water left the surface ocean due to remineralization of organic matter and dissolution of CaCO3 (DDICbio), and ii) a concentration, DICsfc-pi , that reflects the DIC content a water parcel had at the outcrop in pre-industrial times, the equilibrium concentration plus any disequilibrium Thus, DCant = DIC - DDICbio - DICsfc-pi = DIC – DDICbio – DIC280 - DDICdis Assumptions: •natural carbon cycle has remained in steady-state Kuhlbrodt et al, 2006 Inventory of CANT for year 1994 = 110 ± 13 Pg C 15% area 25% inventorio Indian Ocean SO, south of 50ºS 9% inventory, equal area as NA Pacific Ocean 20.3 3 Pg 44.5 5 Pg Atlantic Ocean 44.8 6 Pg (Sabine et al, Science 2004) Atlantica Inventory [Pg C] Pacificb Inventory [Pg C] Indianc Inventory [Pg C] Global Inventory [Pg C] Southern hemisphere 19 28 17 62 Northern hemisphere 28 17 3 48 47 (42%) 45 (40%) 20 (18%) 112 Global a) Lee et al. (submitted) b) Sabine et al. (2002) c) Sabine et al. (1999) Kuhlbrodt et al, 2006 ¿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) Bering St. F air-sea = no se puede medir Storage = se puede estimar, dos maneras Transportes = se pueden calcular 4x 24.5ºN Farewell 0 TProp vρ S, T, P Prop dx dz Vigo H 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, ESENCIAL rS,T,P in-situ density Storage can be mathematically defined as: Storage d C ANTz dz dt where t is time and CANTz dz is the water column inventory of CANT. The Mean Penetration Depth (MPD) of CANT using the formula by Broecker et al. (1979) is: C MPD ANT z dz C ANT ml Assuming that CANT is a where and· C CANT are the CANT concentrations at any depthby conservative tracer (not affected MPD ANTml ml CANT zCdzANTz (z) and at the mixed layer (ml), biology) that has reached its d C ANT z dz dMPD dC ANT ml “transient steady state” · C ANT ml MPD · (profile with a dt dt dt constant shape) Storage d C ANT z dz dt MPD · dC ANT ml dt Storage d C ANT z dz dt MPD · dC ANT ml dt Calculated from: - the temporal change of CANT in the mixed layer. approximated assuming a fully CO2 equilibrated mixed layer keeping pace with the CO2 atmospheric increase. - the MPD can be derived from current TIC observations 2500 4x data WOCE A20 CANT MPD (m) 2000 1500 1000 OacesNAtl-93 data 500 0 65 60 55 50 45 40 Northward Latitude 35 30 25 Table 5.2. Mean Penetration Depth (MPD in meters, according to equation 5.9) of anthropogenic carbon (CANT, meanstandard deviation), CANT increasing rates (mol·m-2·y-1), areas and final CANT storage rates by latitude band and basin. The storage rates for the Arctic ocean (*) and the GIN (Greenland-IcelandNorwegian) seas (+) are also shown. The final storage rates for the Arctic-Subpolar (north of the 4x section) and Temperate (between the 4x and the 24.5ºN sections) regions are shown at the bottom. Latitude Band CANT Area Increasing rate (1012 m2) -2 -1 (mol·m ·y ) MPD (m) East 1070137 0.930.12 2.4 729 West 1466166 1.280.14 2.4 9911 East 1277168 1.110.15 1.4 497 West 1871240 1.630.21 2.1 10914 East 1473187 1.280.16 1.2 506 West 2029262 1.770.23 2.3 12817 East 1410168 1.230.15 1.0 405 West 2104166 1.830.14 1.9 1109 East 1520168 1.320.15 0.8 354 West 1921152 1.670.13 1.6 827 East 1462321 1.270.28 1.3 5312 West 1921152 1.670.13 1.3 706 East 1302432 1.130.38 1.2 4214 West 1739381 1.510.33 1.0 4811 24.5º-30N 30º-35ºN 35º-40ºN 40º-45ºN 45º-50ºN 50º-55ºN 55º-60ºN 67.4+ Final Storage rate (kmol·s-1) Storage rate (kmol·s-1) Basin ArcticSubpolar 68.7* 28850 15250 Temperate 835100 CANT kmol/s 172±111 Bering St. 321±258 4x 24.5ºN 116 ±104 -288±50 630±200 -835±100 Stoll et al. (1996). Álvarez et al. (2003). Rosón et al. (2003). McDonald et al (2003) Holfort et al. (1998). 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 H i , j si E i 1, nreg • 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 method Mikaloff 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 (1765–1995) 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. - Difficult to compare: OGCMs=>mean values, data=> no seasonal or temporal integration - agreements and discrepancies - OGCMs trp at 76ºN not robust, but Trp at more southern latitudes are quite robust and in agreement with data. Figure 5. Uptake, storage, and transport of anthropogenic CO2 in the Atlantic Ocean (Pg C yr−1) based on (a) this study (weighted mean and standard deviation scaled to 1995), (b) the estimates of [Álvarez et al., 2003], where the transport across 24°N was taken from Rosón et al. [2003], (c) Wallace [2001], where the transport across 20°S was taken from Holfort et al. [1998], and (d) Macdonald et al. [2003], where the transports across 10°S and 30°S were taken from Holfort et al. [1998], and the transport across 78°N was taken from Lundberg and Haugan [1996]. 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 36°S constitutes one of the most important sink regions, but much of this anthropogenic CO2 is not stored there, but transported northward with Sub- Antarctic Mode Water. • Models show a similar pattern, but they differ widely in the magnitude of their Southern Ocean uptake. This has large implications for the future uptake of anthropogenic CO2 and thus for the evolution of climate.