scholarly journals Ocean acidification over the next three centuries using a simple global climate carbon-cycle model: projections and sensitivities

2016 ◽  
Vol 13 (15) ◽  
pp. 4329-4342 ◽  
Author(s):  
Corinne A. Hartin ◽  
Benjamin Bond-Lamberty ◽  
Pralit Patel ◽  
Anupriya Mundra
Keyword(s):  
Ocean Acidification ◽  
Ocean Circulation ◽  
Large Scale ◽  
Sensitivity Analyses ◽  
Reduced Form ◽  
Cmip5 Models ◽  
Cmip5 Model ◽  
Low Latitude ◽  
Carbonate System ◽  
Carbon Cycle Model

Abstract. Continued oceanic uptake of anthropogenic CO2 is projected to significantly alter the chemistry of the upper oceans over the next three centuries, with potentially serious consequences for marine ecosystems. Relatively few models have the capability to make projections of ocean acidification, limiting our ability to assess the impacts and probabilities of ocean changes. In this study we examine the ability of Hector v1.1, a reduced-form global model, to project changes in the upper ocean carbonate system over the next three centuries, and quantify the model's sensitivity to parametric inputs. Hector is run under prescribed emission pathways from the Representative Concentration Pathways (RCPs) and compared to both observations and a suite of Coupled Model Intercomparison (CMIP5) model outputs. Current observations confirm that ocean acidification is already taking place, and CMIP5 models project significant changes occurring to 2300. Hector is consistent with the observational record within both the high- (> 55°) and low-latitude oceans (< 55°). The model projects low-latitude surface ocean pH to decrease from preindustrial levels of 8.17 to 7.77 in 2100, and to 7.50 in 2300; aragonite saturation levels (ΩAr) decrease from 4.1 units to 2.2 in 2100 and 1.4 in 2300 under RCP 8.5. These magnitudes and trends of ocean acidification within Hector are largely consistent with the CMIP5 model outputs, although we identify some small biases within Hector's carbonate system. Of the parameters tested, changes in [H+] are most sensitive to parameters that directly affect atmospheric CO2 concentrations – Q10 (terrestrial respiration temperature response) as well as changes in ocean circulation, while changes in ΩAr saturation levels are sensitive to changes in ocean salinity and Q10. We conclude that Hector is a robust tool well suited for rapid ocean acidification projections and sensitivity analyses, and it is capable of emulating both current observations and large-scale climate models under multiple emission pathways.

scholarly journals Projections of ocean acidification over the next three centuries using a simple global climate carbon-cycle model

2015 ◽  
Vol 12 (23) ◽  
pp. 19269-19305 ◽  
Author(s):  
C. A. Hartin ◽  
B. Bond-Lamberty ◽  
P. Patel ◽  
A. Mundra
Keyword(s):  
Ocean Acidification ◽  
Large Scale ◽  
Reduced Form ◽  
Cmip5 Models ◽  
Earth System ◽  
Carbonate System ◽  
Form Model ◽  
Reduced Form Model ◽  
Ph Decrease ◽  
Earth System Models

Abstract. Continued oceanic uptake of anthropogenic CO2 is projected to significantly alter the chemistry of the upper oceans, potentially having serious consequences for the marine ecosystems. Projections of ocean acidification are primarily determined from prescribed emission pathways within large scale earth system models. Rather than running the cumbersome earth system models, we can use a reduced-form model to quickly emulate the CMIP5 models for projection studies under arbitrary emission pathways and for uncertainty analyses of the marine carbonate system. In this study we highlight the capability of Hector v1.1, a reduced-form model, to project changes in the upper ocean carbonate system over the next three centuries. Hector is run under historical emissions and a high emissions scenario (Representative Concentration Pathway 8.5), comparing its output to observations and CMIP5 models that contain ocean biogeochemical cycles. Ocean acidification changes are already taking place, with significant changes projected to occur over the next 300 years. We project a low latitude (> 55°) surface ocean pH decrease from preindustrial conditions by 0.4 units to 7.77 at 2100, and an additional 0.27 units to 7.50 at 2300. Aragonite saturations decrease by 1.85 units to 2.21 at 2100 and an additional 0.80 units to 1.42 at 2300. Under a high emissions scenario, for every 1 °C of future warming we find a 0.107 unit pH decrease and a 0.438 unit decrease in aragonite saturations. Hector reproduces the global historical trends, and future projections with equivalent rates of change over time compared to observations and CMIP5 models. Hector is a robust tool that can be used for quick ocean acidification projections, accurately emulating large scale climate models under multiple emission pathways.

scholarly journals Model constraints on the anthropogenic carbon budget of the Arctic Ocean

2018 ◽  
Author(s):  
Jens Terhaar ◽  
James C. Orr ◽  
Marion Gehlen ◽  
Christian Ethé ◽  
Laurent Bopp
Keyword(s):  
Ocean Acidification ◽  
Arctic Ocean ◽  
Ocean Circulation ◽  
The Arctic ◽  
Global Ocean ◽  
Cmip5 Models ◽  
Lateral Transport ◽  
Coarse Resolution ◽  
The Arctic Ocean ◽  
Anthropogenic Carbon

Abstract. The Arctic Ocean is projected to experience not only amplified climate change but also amplified ocean acidification. Modeling future acidification depends on our ability to simulate baseline conditions and changes over the industrial era. Such centennial-scale changes require a global model to account for exchange between the Arctic and surrounding regions. Yet the coarse resolution of typical global models may poorly resolve that exchange as well as critical features of Arctic Ocean circulation. Here we assess how simulations of Arctic Ocean storage of anthropogenic carbon (Cant), the main driver of open- ocean acidification, differ when moving from coarse to eddy admitting resolution in a global ocean circulation-biogeochemistry model (NEMO-PISCES). The Arctic's regional storage of Cant is enhanced as model resolution increases. While the coarse- resolution model configuration ORCA2 (2°) stores 2.0 Pg C in the Arctic Ocean between 1765 and 2005, the eddy-admitting versions ORCA05 and ORCA025 (1/2° and 1/4°) store 2.4 and 2.6 Pg C. That result from ORCA025 falls within the uncertainty range from a previous data-based Cant storage estimate (2.5 to 3.3 Pg C). Yet those limits may each need to be reduced by about 10 % because data-based Cant concentrations in deep waters remain at ∼ 6 μmol kg−1, while they should be almost negligible by analogy to the near-zero observed CFC-12 concentrations from which they are calculated. Across the three resolutions, there was roughly three times as much anthropogenic carbon that entered the Arctic Ocean through lateral transport than via the flux of CO2 across the air-sea interface. Wider comparison to nine earth system models that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) reveals much larger diversity of stored anthropogenic carbon and lateral transport. Only the CMIP5 models with higher lateral transport obtain Cant inventories that are close to the data-based estimates. Increasing resolution also enhances acidification, e.g., with greater shoaling of the Arctic's average depth of the aragonite saturation horizon during 1960–2012, from 50 m in ORCA2 to 210 m in ORCA025. To assess the potential to further refine modeled estimates of the Arctic Ocean's Cant storage and acidification, sensitivity tests that adjust model parameters are needed given that century-scale global ocean biogeochemical simulations still cannot be run routinely at high resolution.

scholarly journals Modulation of ocean acidification by decadal climate variability in the Gulf of Alaska

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Claudine Hauri ◽  
Rémi Pagès ◽  
Andrew M. P. McDonnell ◽  
Malte F. Stuecker ◽  
Seth L. Danielson ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Ocean Circulation ◽  
Large Scale ◽  
Dissolved Inorganic Carbon ◽  
Model Simulation ◽  
Gulf Of Alaska ◽  
Sea Surface Height ◽  
Sea Surface ◽  
Global Ocean ◽  
Wind Stress Curl

AbstractUptake of anthropogenic carbon dioxide from the atmosphere by the surface ocean is leading to global ocean acidification, but regional variations in ocean circulation and mixing can dampen or accelerate apparent acidification rates. Here we use a regional ocean model simulation for the years 1980 to 2013 and observational data to investigate how ocean fluctuations impact acidification rates in surface waters of the Gulf of Alaska. We find that large-scale atmospheric forcing influenced local winds and upwelling strength, which in turn affected ocean acidification rate. Specifically, variability in local wind stress curl depressed sea surface height in the subpolar gyre over decade-long intervals, which increased upwelling of nitrate- and dissolved inorganic carbon-rich waters and enhanced apparent ocean acidification rates. We define this sea surface height variability as the Northern Gulf of Alaska Oscillation and suggest that it can cause extreme acidification events that are detrimental to ecosystem health and fisheries.

scholarly journals A simple nutrient-dependence mechanism for predicting the stoichiometry of marine ecosystems

2015 ◽  
Vol 112 (27) ◽  
pp. 8199-8204 ◽  
Author(s):  
Eric D. Galbraith ◽  
Adam C. Martiny
Keyword(s):  
Ocean Circulation ◽  
Large Scale ◽  
Phytoplankton Community ◽  
Simple Relationship ◽  
Low Latitude ◽  
Average Composition ◽  
Biogeochemical Models ◽  
The Relationship ◽  
Globally Distributed

It is widely recognized that the stoichiometry of nutrient elements in phytoplankton varies within the ocean. However, there are many conflicting mechanistic explanations for this variability, and it is often ignored in global biogeochemical models and carbon cycle simulations. Here we show that globally distributed particulate P:C varies as a linear function of ambient phosphate concentrations, whereas the N:C varies with ambient nitrate concentrations, but only when nitrate is most scarce. This observation is consistent with the adjustment of the phytoplankton community to local nutrient availability, with greater flexibility of phytoplankton P:C because P is a less abundant cellular component than N. This simple relationship is shown to predict the large-scale, long-term average composition of surface particles throughout large parts of the ocean remarkably well. The relationship implies that most of the observed variation in N:P actually arises from a greater plasticity in the cellular P:C content, relative to N:C, such that as overall macronutrient concentrations decrease, N:P rises. Although other mechanisms are certainly also relevant, this simple relationship can be applied as a first-order basis for predicting organic matter stoichiometry in large-scale biogeochemical models, as illustrated using a simple box model. The results show that including variable P:C makes atmospheric CO2 more sensitive to changes in low latitude export and ocean circulation than a fixed-stoichiometry model. In addition, variable P:C weakens the relationship between preformed phosphate and atmospheric CO2 while implying a more important role for the nitrogen cycle.

scholarly journals Centennial Changes of the Global Water Cycle in CMIP5 Models

2015 ◽  
Vol 28 (16) ◽  
pp. 6489-6502 ◽  
Author(s):  
Samuel J. Levang ◽  
Raymond W. Schmitt
Keyword(s):  
Ocean Circulation ◽  
Large Scale ◽  
Water Cycle ◽  
Cmip5 Models ◽  
Atmospheric Moisture ◽  
Surface Salinity ◽  
Global Water Cycle ◽  
Emissions Scenarios ◽  
Evaporation Minus Precipitation ◽  
Global Water

Abstract The global water cycle is predicted to intensify under various greenhouse gas emissions scenarios. Here the nature and strength of the expected changes for the ocean in the coming century are assessed by examining the output of several CMIP5 model runs for the periods 1990–2000 and 2090–2100 and comparing them to a dataset built from modern observations. Key elements of the water cycle, such as the atmospheric vapor transport, the evaporation minus precipitation over the ocean, and the surface salinity, show significant changes over the coming century. The intensification of the water cycle leads to increased salinity contrasts in the ocean, both within and between basins. Regional projections for several areas important to large-scale ocean circulation are presented, including the export of atmospheric moisture across the tropical Americas from Atlantic to Pacific Ocean, the freshwater gain of high-latitude deep water formation sites, and the basin averaged evaporation minus precipitation with implications for interbasin mass transports.

A Near-Uniform Basin-Wide Sea Level Fluctuation of the Mediterranean Sea

2007 ◽  
Vol 37 (2) ◽  
pp. 338-358 ◽  
Author(s):  
Ichiro Fukumori ◽  
Dimitris Menemenlis ◽  
Tong Lee
Keyword(s):  
Atlantic Ocean ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Ocean Circulation ◽  
Large Scale ◽  
Circulation Model ◽  
Level Fluctuation ◽  
Strait Of Gibraltar ◽  
Sea Level Fluctuation ◽  
The Mediterranean

Abstract A new basin-wide oscillation of the Mediterranean Sea is identified and analyzed using sea level observations from the Ocean Topography Experiment (TOPEX)/Poseidon satellite altimeter and a numerical ocean circulation model. More than 50% of the large-scale, nontidal, and non-pressure-driven variance of sea level can be attributed to this oscillation, which is nearly uniform in phase and amplitude across the entire basin. The oscillation has periods ranging from 10 days to several years and has a magnitude as large as 10 cm. The model suggests that the fluctuations are driven by winds at the Strait of Gibraltar and its neighboring region, including the Alboran Sea and a part of the Atlantic Ocean immediately to the west of the strait. Winds in this region force a net mass flux through the Strait of Gibraltar to which the Mediterranean Sea adjusts almost uniformly across its entire basin with depth-independent pressure perturbations. The wind-driven response can be explained in part by wind setup; a near-stationary balance is established between the along-strait wind in this forcing region and the sea level difference between the Mediterranean Sea and the Atlantic Ocean. The amplitude of this basin-wide wind-driven sea level fluctuation is inversely proportional to the setup region’s depth but is insensitive to its width including that of Gibraltar Strait. The wind-driven fluctuation is coherent with atmospheric pressure over the basin and contributes to the apparent deviation of the Mediterranean Sea from an inverse barometer response.

scholarly journals Variability in larval gut pH regulation defines sensitivity to ocean acidification in six species of the Ambulacraria superphylum

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171066 ◽  
Author(s):  
Marian Hu ◽  
Yung-Che Tseng ◽  
Yi-Hsien Su ◽  
Etienne Lein ◽  
Hae-Gyeong Lee ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Large Scale ◽  
Environmental Changes ◽  
Ph Regulation ◽  
Gastric Ph ◽  
Differential Sensitivity ◽  
Larval Stages ◽  
Regulatory Systems ◽  
Alkaline Conditions ◽  
Gut Ph

The unusual rate and extent of environmental changes due to human activities may exceed the capacity of marine organisms to deal with this phenomenon. The identification of physiological systems that set the tolerance limits and their potential for phenotypic buffering in the most vulnerable ontogenetic stages become increasingly important to make large-scale projections. Here, we demonstrate that the differential sensitivity of non-calcifying Ambulacraria (echinoderms and hemichordates) larvae towards simulated ocean acidification is dictated by the physiology of their digestive systems. Gastric pH regulation upon experimental ocean acidification was compared in six species of the superphylum Ambulacraria. We observed a strong correlation between sensitivity to ocean acidification and the ability to regulate gut pH. Surprisingly, species with tightly regulated gastric pH were more sensitive to ocean acidification. This study provides evidence that strict maintenance of highly alkaline conditions in the larval gut of Ambulacraria early life stages may dictate their sensitivity to decreases in seawater pH. These findings highlight the importance of identifying and understanding pH regulatory systems in marine larval stages that may contribute to substantial energetic challenges under near-future ocean acidification scenarios.

One-step Functionalization of Mildly and Strongly Reduced Graphene Oxide with Maleimide: An Experimental and Theoretical Investigation of the Diels-Alder [4+2] Cycloaddition Reaction

2021 ◽  
Author(s):  
Alfonso Ferretti ◽  
Sourab Sinha ◽  
Luca Sagresti ◽  
Esteban Araya-Hermosilla ◽  
Mirko Prato ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Large Scale ◽  
Cycloaddition Reaction ◽  
Diels Alder ◽  
Reduced Form ◽  
Graphene Nanocomposites ◽  
Exfoliated Graphene ◽  
Reduced Graphene ◽  
One Step

For large-scale graphene applications, such as the production of polymer-graphene nanocomposites, exfoliated graphene oxide (GO) and its reduced form (rGO) are presently considered very suitable starting material, showing enhanced chemical...

scholarly journals Development of PM<sub>2.5</sub> source impact spatial fields using a hybrid source apportionment air quality model

2015 ◽  
Vol 8 (7) ◽  
pp. 2153-2165 ◽  
Author(s):  
C. E. Ivey ◽  
H. A. Holmes ◽  
Y. T. Hu ◽  
J. A. Mulholland ◽  
A. G. Russell
Keyword(s):  
Air Quality ◽  
Source Apportionment ◽  
Large Scale ◽  
Major Ions ◽  
Current Knowledge ◽  
Direct Method ◽  
Hybrid Approach ◽  
Sensitivity Analyses ◽  
Adjustment Factors ◽  
The Impact

Abstract. An integral part of air quality management is knowledge of the impact of pollutant sources on ambient concentrations of particulate matter (PM). There is also a growing desire to directly use source impact estimates in health studies; however, source impacts cannot be directly measured. Several limitations are inherent in most source apportionment methods motivating the development of a novel hybrid approach that is used to estimate source impacts by combining the capabilities of receptor models (RMs) and chemical transport models (CTMs). The hybrid CTM–RM method calculates adjustment factors to refine the CTM-estimated impact of sources at monitoring sites using pollutant species observations and the results of CTM sensitivity analyses, though it does not directly generate spatial source impact fields. The CTM used here is the Community Multiscale Air Quality (CMAQ) model, and the RM approach is based on the chemical mass balance (CMB) model. This work presents a method that utilizes kriging to spatially interpolate source-specific impact adjustment factors to generate revised CTM source impact fields from the CTM–RM method results, and is applied for January 2004 over the continental United States. The kriging step is evaluated using data withholding and by comparing results to data from alternative networks. Data withholding also provides an estimate of method uncertainty. Directly applied (hybrid, HYB) and spatially interpolated (spatial hybrid, SH) hybrid adjustment factors at withheld observation sites had a correlation coefficient of 0.89, a linear regression slope of 0.83 ± 0.02, and an intercept of 0.14 ± 0.02. Refined source contributions reflect current knowledge of PM emissions (e.g., significant differences in biomass burning impact fields). Concentrations of 19 species and total PM2.5 mass were reconstructed for withheld observation sites using HYB and SH adjustment factors. The mean concentrations of total PM2.5 at withheld observation sites were 11.7 (± 8.3), 16.3 (± 11), 8.59 (± 4.7), and 9.2 (± 5.7) μg m−3 for the observations, CTM, HYB, and SH predictions, respectively. Correlations improved for concentrations of major ions, including nitrate (CMAQ–DDM (decoupled direct method): 0.404, SH: 0.449), ammonium (CMAQ–DDM: 0.454, SH: 0.492), and sulfate (CMAQ–DDM: 0.706, SH: 0.730). Errors in simulated concentrations of metals were reduced considerably: 295 % (CMAQ–DDM) to 139 % (SH) for vanadium; and 1340 % (CMAQ–DDM) to 326 % (SH) for manganese. Errors in simulated concentrations of some metals are expected to remain given the uncertainties in source profiles. Species concentrations were reconstructed using SH results, and the error relative to observed concentrations was greatly reduced as compared to CTM-simulated concentrations. Results demonstrate that the hybrid method along with a spatial extension can be used for large-scale, spatially resolved source apportionment studies where observational data are spatially and temporally limited.

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