marta Álvarez rodríguez
DESCRIPTION
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. IEO - A Coruña. Palma de Mallorca, October 2011. Ciclo global del carbono. - PowerPoint PPT PresentationTRANSCRIPT
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Ciclo global del carbono
+65 -125
1.7 Land use change
+18
21.9 20
1.9 Land sink
1.6
+100
5.4
-220
+161
y su perturbación antropogénica
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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:
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Anthropogenic CO2 Budget 1800 to 1994CO2 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
(6) Terrestrial sinks = [(1)+(2)]-[(4)+(5)] 83
a: 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
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- 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
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Method Carbon Uptake Reference (Pg C yr-1)
Measurements of sea-air 2.1 ± 0.5 Takahashi et al. [2002] pCO2 Diff erence I nversion of atmospheric 1.8 ± 1.0 Gurney et al. [2002] CO2 observations I nversions of ocean transport models and observed DI C 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] OCMI P-2 Model simulations 2.38 ± 0.28 Orr et a.l [2004] Based on measured atm. O2 and CO2 inventories corrected f or ocean warming and strat. 2.2 ± 0.5
Keeling & Manning [submitted]
GCM Model of Ocean Carbon 1.93 Wetzel et al. (2005) CFC ages 2.0 ± 0.4 McNeil et al. (2003) Fluxes are normalized to 1990-1999 (except Keeling & Manning which is f or 1993-2004) and corrected f or pre-industrial degassing flux of ~0.6 Pg C yr–1.
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Globally integrated flux: 2.2 PgC yr-1
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Preindustrial Flux
Anthropogenic Flux
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WOCE/JGOFS/OACES Global COWOCE/JGOFS/OACES Global CO22 Survey 1991-1997 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.
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+ 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%
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GSS’96 defined the semiconservative parameter C*(), it depends on the anthropogenic input, thus, the water mass age (), and its include the air-sea desequilibrium constant with time:
C*() = CANT + CTdis
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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 (DICbio), 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,Cant = DIC - DICbio - DICsfc-pi = DIC – DICbio – DIC280 - DICdis
Assumptions:•natural carbon cycle has remained in steady-state
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44.5 5 Pg
44.8 6 Pg 20.3 3 Pg
Indian Ocean
Pacific Ocean Atlantic Ocean
(Sabine et al, Science 2004)
Inventory of CInventory of CANTANT for year 1994 = 110 ± 13 Pg C for year 1994 = 110 ± 13 Pg C
15% area
25% inventorio
SO, south of 50ºS 9% inventory, equal area as NA
Kuhlbrodt et al, 2006
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Atlantica
Inventory[Pg C]
Pacificb
Inventory[Pg C]
Indianc
Inventory[Pg C]
GlobalInventory
[Pg C]
Southern hemisphere 19 28 17 62
Northern hemisphere 28 17 3 48
Global 47 (42%) 45 (40%) 20 (18%) 112
a) Lee et al. (submitted)b) Sabine et al. (2002)c) Sabine et al. (1999)
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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.
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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...
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4x 24.5ºNBering St.
F air-sea = – (Storage + TS + TN)
F air-sea = no se puede medir
Storage = se puede estimar, dos maneras
Transportes = se pueden calcular
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Farewell
Vigo
0
HPT,S,Prop dzdxPropρvT
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
S,T,P in-situ density
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Storage can be mathematically defined as:
dt
dzCdStorage
ANTz
where t is time and CANTz dz is the water column inventory of CANT.
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The Mean Penetration Depth (MPD) of CANT using the formula by Broecker et al. (1979) is:
ml ANT
z ANT
C
dzCMPD
where CANTz and CANTml are the CANT concentrations at any depth (z) and at the mixed layer (ml),
ml ANT z ANT C · MPDdzC
dtdC · MPDC ·
dtdMPD
dt
dzCdml ANT
ml ANT z ANT
dtdC · MPD
dt
dzCdStorage ml ANT z ANT
Assuming that CANT is a conservative tracer (not affected by biology) that has reached its
“transient steady state” (profile with a
constant shape)
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dtdC · MPD
dt
dzCdStorage ml ANT z ANT
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.
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Northward Latitude
253035404550556065
CA
NT
MPD
(m)
0
500
1000
1500
2000
2500
4x data
OacesNAtl-93 data
WOCE A20
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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-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 24.5ºN sections) regions are shown at the bottom.
Latitude Band Basin MPD (m) CANT
Increasing rate (mol·m-2·y-1)
Area (1012 m2)
Storage rate
(kmol·s-1) East 1070137 0.930.12 2.4 729
24.5º-30N West 1466166 1.280.14 2.4 9911
East 1277168 1.110.15 1.4 497 30º-35ºN
West 1871240 1.630.21 2.1 10914
East 1473187 1.280.16 1.2 506 35º-40ºN
West 2029262 1.770.23 2.3 12817
East 1410168 1.230.15 1.0 405 40º-45ºN
West 2104166 1.830.14 1.9 1109
East 1520168 1.320.15 0.8 354 45º-50ºN
West 1921152 1.670.13 1.6 827
East 1462321 1.270.28 1.3 5312 50º-55ºN
West 1921152 1.670.13 1.3 706
East 1302432 1.130.38 1.2 4214 55º-60ºN
West 1739381 1.510.33 1.0 4811
67.4+
68.7* Arctic-Subpolar
15250
28850 Final Storage rate (kmol·s-1)
Temperate 835100
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4x 24.5ºNBering St.172111 321258
-28850 -835100
116104 630200
CANT kmol/s
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Álvarez et al. (2003).
Stoll et al. (1996).
Rosón et al. (2003).
McDonald et al (2003)
Holfort et al. (1998).
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Ocean Inversion method• The ocean is divided into n regions
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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 method
nregi
ijij EsHC,1
,
Mikaloff Fletcher et al. (GBC, 2006)
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Mikaloff Fletcher et al. (GBC, 2006)
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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.
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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].
- 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.
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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
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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)
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• 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.