Decadal changes in dissolved inorganic carbon in the Pacific Ocean

Kouketsu, Shinya; Murata, Akihiko; Doi, Toshimasa

doi:10.1029/2012gb004413

Cited by 26 publications

(39 citation statements)

References 48 publications

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“…Kouketsu et al () estimated Pacific C anth increased by 8.4 (±0.5) PgC between 50°S and 65°N in the earlier decade (1995 to 2005), where we find 7.7 (±1.1) PgC accumulation (Table ). The majority of this (statistically insignificant) discrepancy originates in the 20°S to 50°S latitude band where Murata et al () found more C anth than we do along P06 (Table ).…”

Section: Resultssupporting

confidence: 72%

Pacific Anthropogenic Carbon Between 1991 and 2017

Carter

Feely

Wanninkhof

et al. 2019

Global Biogeochemical Cycles

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We estimate anthropogenic carbon (Canth) accumulation rates in the Pacific Ocean between 1991 and 2017 from 14 hydrographic sections that have been occupied two to four times over the past few decades, with most sections having been recently measured as part of the Global Ocean Ship‐based Hydrographic Investigations Program. The rate of change of Canth is estimated using a new method that combines the extended multiple linear regression method with improvements to address the challenges of analyzing multiple occupations of sections spaced irregularly in time. The Canth accumulation rate over the top 1,500 m of the Pacific increased from 8.8 (±1.1, 1σ) Pg of carbon per decade between 1995 and 2005 to 11.7 (±1.1) PgC per decade between 2005 and 2015. For the entire Pacific, about half of this decadal increase in the accumulation rate is attributable to the increase in atmospheric CO2, while in the South Pacific subtropical gyre this fraction is closer to one fifth. This suggests a substantial enhancement of the accumulation of Canth in the South Pacific by circulation variability and implies that a meaningful portion of the reinvigoration of the global CO2 sink that occurred between ~2000 and ~2010 could be driven by enhanced ocean Canth uptake and advection into this gyre. Our assessment suggests that the accuracy of Canth accumulation rate reconstructions along survey lines is limited by the accuracy of the full suite of hydrographic data and that a continuation of repeated surveys is a critical component of future carbon cycle monitoring.

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Section: Resultssupporting

confidence: 72%

Pacific Anthropogenic Carbon Between 1991 and 2017

Carter

Feely

Wanninkhof

et al. 2019

Global Biogeochemical Cycles

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“…The principal contributor to ΔΩ was increases of anthropogenic CO 2 (section 6). The faster rates of decrease in our results can therefore be attributed to rapid accumulation of anthropogenic CO 2 in the South Pacific [ Murata et al , ; Waters et al , ; Feely et al , ; Kouketsu et al , ]. In the case of region 3, we believe that another factor also contributed to hastening the progression of OA.…”

Section: Discussionsupporting

confidence: 63%

“…In the western part of section P21, the Ω arg saturation horizon was at a depth of about 1200 dbar in Antarctic Intermediate Water (Figure ). This finding suggests that its upward migration was probably accelerated by anthropogenic CO 2 from the Southern Ocean [ Kouketsu et al , ].…”

Section: Discussionmentioning

confidence: 99%

Detecting the progression of ocean acidification from the saturation state of CaCO₃ in the subtropical South Pacific

Murata

Hayashi

Kumamoto

et al. 2015

Global Biogeochemical Cycles

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Progression of ocean acidification in the subtropical South Pacific was investigated by using high-quality data from trans-Pacific zonal section at 17°S (World Ocean Circulation Experiment section P21) collected in 1994 and 2009. During this 15 year period, the CaCO 3 saturation state of seawater with respect to calcite (Ω cal ) and aragonite (Ω arg ) in the upper water column (<400 dbar) decreased at rates of 0.037 a À1 and 0.025 a À1, respectively, east of 145°W longitude; these rates are among the fastest in the world's oceans. In contrast, at longitudes 170°E-145°W, Ω cal and Ω arg decreased relatively slowly, at 0.008 a À1 and 0.005 a À1, respectively. The Ω arg saturation horizon occurred at a depth of about 1200 dbar at the westernmost end of the section and shoaled eastward to about 20 dbar. From 1994 to 2009, it migrated upward at a rate of 5.2 dbar a À1 west of 145°W. Decomposition of the temporal changes of Ω (ΔΩ) showed that the accumulation of anthropogenic CO 2 in the ocean accounted for more than half of ΔΩ. The more rapid rate of decline of Ω in the eastern section was attributable to a relatively large contribution of organic matter remineralization, whereas the slower rate in the central section was attributed to a decrease of anthropogenic CO 2 uptake caused by rising water temperatures. An important finding of this study was that acidification of the upper water column was enhanced by processes related to the oxygen minimum zone in the eastern subtropical South Pacific Ocean.

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“…Based on CT changes between the two repeated visits of the longitudinal P21 line (18° S close to the OUTPACE transect) in 1994 and 2009, Kouketsu et al (2013) shows faster increase of CANT in the western part than in the eastern part of the section. ) for the upper water column at the latitude of OUTPACE area in good agreement with our estimates in WGY in the upper water column.…”

Section: Hydrological Context Along the Outpace Transectmentioning

confidence: 99%

“…Even if, due to its remoteness from land, it remains largely under-explored by oceanographic vessels compared to other oceanic areas, the Pacific Ocean has been covered by cruises along long sections (the "P sections" from the WOCE program). Most of these sections have been revisited during the last years (see for example Sabine et al, 2008or Kouketsu et al, 2013. In a recent study based on repeated sections in the Pacific (P16 at 150W),…”

Section: Introductionmentioning

confidence: 99%

Carbonate system distribution, anthropogenic carbon and acidification in the Western Tropical South Pacific (OUTPACE 2015 transect)

Wagener¹,

Metzl²,

Caffin³

et al. 2018

Preprint

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Abstract.The western tropical South Pacific was sampled along a longitudinal 4000 km transect (OUTPACE cruise, 18 Feb., 3 Apr. 2015) for measurement of carbonates parameters (total alkalinity and total inorganic carbon) between the Melanesian Archipelago (MA) and the western part of the South Pacific gyre (WGY). This manuscript reports this new dataset and derived properties: pH on the total scale (pHT) and the CaCO3 saturation state with respect to calcite (Ωcal) and aragonite (Ωara). We also estimate anthropogenic carbon (CANT) distribution in the water column using the TrOCA method (Tracer combining Oxygen, inorganic Carbon and total Alkalinity). Along the OUTPACE transect, CANT inventories of 37 -43 mol m -2 were estimated with higher CANT inventories in MA waters (due to a deeper penetration of CANT in the intermediate waters) than in the WGY waters although highest CANT concentrations were detected in the sub-surface waters of WGY. By combining our OUTPACE dataset with data available in GLODAPv2 (1974GLODAPv2 ( -2009, temporal changes in oceanic inorganic carbon were evaluated. An increase of 1.3 to 1.6 µmol kg IntroductionHuman activities inject about 10 13 kg of carbon per year to the atmosphere which might have major consequences on climate. It is recognized that the ocean plays a key role in the control of atmospheric CO2 through uptake by the so called "oceanic carbon pump". Through this "pump", the ocean sequesters ca. 30% of the CO2 injected annually in the atmosphere by human activities (Le Quéré et al., 2018). A consequence of the ocean carbon uptake is a decrease of the oceanic pH (Feely et al, 2004) which is described as ocean acidification (the so-called "other" CO2 problem). Effects of ocean acidification have been observed on marine organisms and could affect the marine ecosystems (Riebesell et al., 2000). Improving our understanding of the oceanic CO2 uptake relies primarily on observations of the marine carbonate cycle. Studies on the oceanic carbonate cycle have been mostly conducted in the frame of international programs. The World Ocean Circulation Experiment (WOCE) and the Joint Global Flux Study (JGOFS) in the 90's have coordinated oceanographic cruises along large sections in the ocean to collect samples through the water column and to perform accurate measurements of carbonate parameters and ancillary parameters (temperature, salinity, dissolved oxygen, nutrients,...). Since 2000, efforts have been made to "revisit" oceanic sections according to the WOCE strategy in order to assess oceanic changes at the scale of a decade. These programs have generated important databases for oceanic carbonate chemistry (e.g. GLODAP_V2 -Olsen et al., 2016).In order to better assess the role of the ocean on the global carbon cycle, the concept of oceanic anthropogenic carbon (hereafter named CANT) has been introduced and refers to the fraction of dissolved inorganic carbon (CT) in the ocean that originates from carbon injected by human activities in the atmosphere since the industrial revolutio...

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Decadal changes in dissolved inorganic carbon in the Pacific Ocean

Cited by 26 publications

References 48 publications

Pacific Anthropogenic Carbon Between 1991 and 2017

Pacific Anthropogenic Carbon Between 1991 and 2017

Detecting the progression of ocean acidification from the saturation state of CaCO₃ in the subtropical South Pacific

Carbonate system distribution, anthropogenic carbon and acidification in the Western Tropical South Pacific (OUTPACE 2015 transect)

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Decadal changes in dissolved inorganic carbon in the Pacific Ocean

Cited by 26 publications

References 48 publications

Pacific Anthropogenic Carbon Between 1991 and 2017

Pacific Anthropogenic Carbon Between 1991 and 2017

Detecting the progression of ocean acidification from the saturation state of CaCO3 in the subtropical South Pacific

Carbonate system distribution, anthropogenic carbon and acidification in the Western Tropical South Pacific (OUTPACE 2015 transect)

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Detecting the progression of ocean acidification from the saturation state of CaCO₃ in the subtropical South Pacific