Oxygen trends over five decades in the North Atlantic

Stendardo, I.; Gruber, Nicolas

doi:10.1029/2012jc007909

Cited by 86 publications

(101 citation statements)

References 88 publications

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“…Over the mid-latitudes, patterns of projected changes in subsurface O 2 are broadly consistent with observations collected over the past several decades (Helm et al, 2011;Stendardo and Gruber, 2012;Takatani et al, 2012). Yet there is no such model-data agreement over most of the tropical oceans.…”

Section: General Descriptionsupporting

confidence: 66%

Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models

et al. 2013

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Abstract. Ocean ecosystems are increasingly stressed by human-induced changes of their physical, chemical and biological environment. Among these changes, warming, acidification, deoxygenation and changes in primary productivity by marine phytoplankton can be considered as four of the major stressors of open ocean ecosystems. Due to rising atmospheric CO 2 in the coming decades, these changes will be amplified. Here, we use the most recent simulations performed in the framework of the Coupled Model Intercomparison Project 5 to assess how these stressors may evolve over the course of the 21st century. The 10 Earth system models used here project similar trends in ocean warming, acidification, deoxygenation and reduced primary productivity for each of the IPCC's representative concentration pathways (RCPs) over the 21st century. For the "businessas-usual" scenario RCP8.5, the model-mean changes in the 2090s (compared to the 1990s) for sea surface temperature, sea surface pH, global O 2 content and integrated primary productivity amount to +2.73 (±0.72) • C, −0.33 (±0.003) pH unit, −3.45 (±0.44) % and −8.6 (±7.9) %, respectively. For the high mitigation scenario RCP2.6, corresponding changes are +0.71 (±0.45) • C, −0.07 (±0.001) pH unit, −1.81 (±0.31) % and −2.0 (±4.1) %, respectively, illustrating the effectiveness of extreme mitigation strategies. Although these stressors operate globally, they display distinct regional patterns and thus do not change coincidentally. Large decreases in O 2 and in pH are simulated in global ocean intermediate and mode waters, whereas large reductions in primary production are simulated in the tropics and in the North Atlantic. Although temperature and pH projections are robust across models, the same does not hold for projections of subsurface O 2 concentrations in the tropics and global and regional changes in net primary productivity. These high uncertainties in projections of primary productivity and subsurface oxygen prompt us to continue intermodel comparisons to understand these model differences, while calling for caution when using the CMIP5 models to force regional impact models.

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Section: General Descriptionsupporting

confidence: 66%

Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models

et al. 2013

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“…6), probably due to a decline in preformed DIC values, i.e. a loss of solubility as a consequence of the positive surface temperature trends in the Irminger Sea from 1991-2015 (Stendardo and Gruber, 2012;Maze et al, 2012). The long-term warming trends in the surface ocean and thus the decreasing O 2 solubility leads to a deoxygenation of −0.8 ± 0.3 mol m −2 yr −1 over the 24-year period, which is consistent with the suggested loss in preformed DIC.…”

Section: Discussionmentioning

confidence: 99%

Inorganic carbon and water masses in the Irminger Sea since 1991

et al. 2018

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Abstract. The subpolar region in the North Atlantic is a major sink for anthropogenic carbon. While the storage rates show large interannual variability related to atmospheric forcing, less is known about variability in the natural dissolved inorganic carbon (DIC) and the combined impact of variations in the two components on the total DIC inventories. Here, data from 15 cruises in the Irminger Sea covering the 24-year period between 1991 and 2015 were used to determine changes in total DIC and its natural and anthropogenic components. Based on the results of an extended optimum multiparameter analysis (eOMP), the inventory changes are discussed in relation to the distribution and evolution of the main water masses. The inventory of DIC increased by 1.43 ± 0.17 mol m −2 yr −1 over the period, mainly driven by the increase in anthropogenic carbon (1.84 ± 0.16 mol m −2 yr −1 ) but partially offset by a loss of natural DIC (−0.57 ± 0.22 mol m −2 yr −1 ). Changes in the carbon storage rate can be driven by concentration changes in the water column, for example due to the ageing of water masses, or by changes in the distribution of water masses with different concentrations either by local formation or advection. A decomposition of the trends into their main drivers showed that variations in natural DIC inventories are mainly driven by changes in the layer thickness of the main water masses, while anthropogenic carbon is most affected by concentration changes. The storage rates of anthropogenic carbon are sensitive to data selection, while changes in DIC inventory show a robust signal on short timescales associated with the strength of convection.

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“…Recently, Stendardo and Gruber (2012) used a long-term data set for dissolved oxygen in the North Atlantic Ocean to assess any trends over the past 49 yr. She finds a complex pattern of temporal changes in oxygen concentrations; the upper water masses have generally lost oxygen, particularly in the eastern and northern Atlantic, whereas deeper layers have generally gained oxygen, particularly in the southwestern part of the North Atlantic. The results are based on observed changes in oxygen concentration for different density intervals (i.e.…”

Section: Discussionmentioning

confidence: 99%

Changes in column inventories of carbon and oxygen in the Atlantic Ocean

Tanhua

2012

Biogeosciences

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Abstract. Increasing concentrations of dissolved inorganic carbon (DIC) in the interior ocean are expected as a direct consequence of increasing concentrations of CO 2 in the atmosphere. This extra DIC is often referred to as anthropogenic carbon (C ant ), and its inventory, or increase rate, in the interior ocean has previously been estimated by a multitude of observational approaches. Each of these methods is associated with hard to test assumptions since C ant cannot be directly observed. Results from a simpler concept with fewer assumptions applied to the Atlantic Ocean are reported on here using two large data collections of carbon relevant bottle data. The change in column inventory on decadal time scales, i.e. the storage rate, of DIC, respiration compensated DIC and oxygen is calculated for the Atlantic Ocean. We report storage rates and the confidence intervals of the mean trend at the 95 % level (CI), reflecting the mean trend but not considering potential biasing effects of the spatial and temporal sampling. For the whole Atlantic Ocean the mean trends for DIC and oxygen are non-zero at the 95 % confidence level: DIC: 0.86 (CI: 0.72-1.00) and oxygen: −0.24 (CI: −0.41-(−0.07)) mol m −2 yr −1 . For oxygen, the whole Atlantic trend is dominated by the subpolar North Atlantic, whereas for other regions the O 2 trends are not significant. The storage rates are similar to changes found by other studies, although with large uncertainty. For the subpolar North Atlantic the storage rates show significant temporal and regional variation of all variables. This seems to be due to variations in the prevalence of subsurface water masses with different DIC and oxygen concentrations leading to sometimes different signs of storage rates for DIC compared to published C ant estimates. This study suggest that accurate assessment of the uptake of CO 2 by the oceans will require accounting not only for processes that influence C ant but also additional processes that modify CO 2 storage.

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Oxygen trends over five decades in the North Atlantic

Cited by 86 publications

References 88 publications

Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models

Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models

Inorganic carbon and water masses in the Irminger Sea since 1991

Changes in column inventories of carbon and oxygen in the Atlantic Ocean

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