scholarly journals Emergence of multiple ocean ecosystem drivers in a large ensemble suite with an Earth system model

2015 ◽  
Vol 12 (11) ◽  
pp. 3301-3320 ◽  
Author(s):  
K. B. Rodgers ◽  
J. Lin ◽  
T. L. Frölicher
Keyword(s):  
Southern Ocean ◽  
Marine Ecosystem ◽  
Marine Ecosystems ◽  
Earth System Model ◽  
System Model ◽  
Global Ocean ◽  
Earth System ◽  
Biological Productivity ◽  
The Tropics ◽  
Ecosystem Drivers

Abstract. Marine ecosystems are increasingly stressed by human-induced changes. Marine ecosystem drivers that contribute to stressing ecosystems – including warming, acidification, deoxygenation and perturbations to biological productivity – can co-occur in space and time, but detecting their trends is complicated by the presence of noise associated with natural variability in the climate system. Here we use large initial-condition ensemble simulations with an Earth system model under a historical/RCP8.5 (representative concentration pathway 8.5) scenario over 1950–2100 to consider emergence characteristics for the four individual and combined drivers. Using a 1-standard-deviation (67% confidence) threshold of signal to noise to define emergence with a 30-year trend window, we show that ocean acidification emerges much earlier than other drivers, namely during the 20th century over most of the global ocean. For biological productivity, the anthropogenic signal does not emerge from the noise over most of the global ocean before the end of the 21st century. The early emergence pattern for sea surface temperature in low latitudes is reversed from that of subsurface oxygen inventories, where emergence occurs earlier in the Southern Ocean. For the combined multiple-driver field, 41% of the global ocean exhibits emergence for the 2005–2014 period, and 63% for the 2075–2084 period. The combined multiple-driver field reveals emergence patterns by the end of this century that are relatively high over much of the Southern Ocean, North Pacific, and Atlantic, but relatively low over the tropics and the South Pacific. For the case of two drivers, the tropics including habitats of coral reefs emerges earliest, with this driven by the joint effects of acidification and warming. It is precisely in the regions with pronounced emergence characteristics where marine ecosystems may be expected to be pushed outside of their comfort zone determined by the degree of natural background variability to which they are adapted. The results underscore the importance of sustained multi-decadal observing systems for monitoring multiple ecosystems drivers.

scholarly journals Emergence of multiple ocean ecosystem drivers in a large ensemble suite with an earth system model

2014 ◽  
Vol 11 (12) ◽  
pp. 18189-18227 ◽  
Author(s):  
K. B. Rodgers ◽  
J. Lin ◽  
T. L. Frölicher
Keyword(s):  
Southern Ocean ◽  
Marine Ecosystems ◽  
Earth System Model ◽  
Mitigation Strategies ◽  
System Model ◽  
Global Ocean ◽  
Earth System ◽  
Biological Productivity ◽  
Ocean Ecosystem ◽  
Ecosystem Drivers

Abstract. Marine ecosystems are increasingly impacted by human-induced changes. Ocean ecosystem drivers – including warming, acidification, deoxygenation and perturbations to biological productivity – can co-occur in space and time, but detecting their trends is complicated by the presence of noise associated with natural variability in the climate system. Here we use Large Initial-Condition Ensemble Simulations with a comprehensive Earth System Model under a historical/RCP8.5 pathway over 1950–2100 to consider emergence characteristics for the four individual and combined drivers. Using a one-standard deviation (67% confidence) threshold of signal-to-noise to define emergence with a 30 yr trend window, we show that ocean acidification emerges much earlier than other drivers, namely during the 20th century over most of the global ocean. For biological productivity, the anthropogenic signal does not emerge from the noise over most of the global ocean before the end of the 21st century. The early emergence pattern for sea surface temperature in low latitudes is reversed from that of subsurface oxygen inventories, where emergence occurs earlier in the Southern Ocean. For the combined multiple-driver field, 41% of the global ocean exhibits emergence for the 2005–2014 period, and 63% for the 2075–2084 period. The combined multiple-driver field reveals emergence patterns by the end of this century that are relatively high over much of the Southern Ocean, North Pacific, and Atlantic, but relatively low over the tropics and the South Pacific. In regions with pronounced emergence characteristics, marine ecosystems can be expected to be pushed outside of their comfort zone determined by the degree of natural background variability to which they are adapted. The results here thus have implications not only for optimization of the ocean observing system, but also for risk assessment and mitigation strategies.

scholarly journals Marine Ecosystem Dynamics and Biogeochemical Cycling in the Community Earth System Model [CESM1(BGC)]: Comparison of the 1990s with the 2090s under the RCP4.5 and RCP8.5 Scenarios

2013 ◽  
Vol 26 (23) ◽  
pp. 9291-9312 ◽  
Author(s):  
J. Keith Moore ◽  
Keith Lindsay ◽  
Scott C. Doney ◽  
Matthew C. Long ◽  
Kazuhiro Misumi
Keyword(s):  
Climate Change ◽  
Ocean Circulation ◽  
Marine Ecosystem ◽  
Earth System Model ◽  
Ecosystem Dynamics ◽  
System Model ◽  
Earth System ◽  
Production Scale ◽  
Export Production ◽  
Community Earth System Model

The authors compare Community Earth System Model results to marine observations for the 1990s and examine climate change impacts on biogeochemistry at the end of the twenty-first century under two future scenarios (Representative Concentration Pathways RCP4.5 and RCP8.5). Late-twentieth-century seasonally varying mixed layer depths are generally within 10 m of observations, with a Southern Ocean shallow bias. Surface nutrient and chlorophyll concentrations exhibit positive biases at low latitudes and negative biases at high latitudes. The volume of the oxygen minimum zones is overestimated. The impacts of climate change on biogeochemistry have similar spatial patterns under RCP4.5 and RCP8.5, but perturbation magnitudes are larger under RCP8.5. Increasing stratification leads to weaker nutrient entrainment and decreased primary and export production (>30% over large areas). The global-scale decreases in primary and export production scale linearly with the increases in mean sea surface temperature. There are production increases in the high nitrate, low chlorophyll (HNLC) regions, driven by lateral iron inputs from adjacent areas. The increased HNLC export partially compensates for the reductions in non-HNLC waters (~25% offset). Stabilizing greenhouse gas emissions and climate by the end of this century (as in RCP4.5) will minimize the changes to nutrient cycling and primary production in the oceans. In contrast, continued increasing emission of CO2 (as in RCP8.5) will lead to reduced productivity and significant modifications to ocean circulation and biogeochemistry by the end of this century, with more drastic changes beyond the year 2100 as the climate continues to rapidly warm.

scholarly journals Data-constrained assessment of ocean circulation changes since the middle Miocene in an Earth system model

2021 ◽  
Vol 17 (5) ◽  
pp. 2223-2254
Author(s):  
Katherine A. Crichton ◽  
Andy Ridgwell ◽  
Daniel J. Lunt ◽  
Alex Farnsworth ◽  
Paul N. Pearson
Keyword(s):  
Greenhouse Gas ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Middle Miocene ◽  
Earth System Model ◽  
System Model ◽  
Global Ocean ◽  
Earth System ◽  
Cooling Trend

Abstract. Since the middle Miocene (15 Ma, million years ago), the Earth's climate has undergone a long-term cooling trend, characterised by a reduction in ocean temperatures of up to 7–8 ∘C. The causes of this cooling are primarily thought to be due to tectonic plate movements driving changes in large-scale ocean circulation patterns, and hence heat redistribution, in conjunction with a drop in atmospheric greenhouse gas forcing (and attendant ice-sheet growth and feedback). In this study, we assess the potential to constrain the evolving patterns of global ocean circulation and cooling over the last 15 Ma by assimilating a variety of marine sediment proxy data in an Earth system model. We do this by first compiling surface and benthic ocean temperature and benthic carbon-13 (δ13C) data in a series of seven time slices spaced at approximately 2.5 Myr intervals. We then pair this with a corresponding series of tectonic and climate boundary condition reconstructions in the cGENIE (“muffin” release) Earth system model, including alternative possibilities for an open vs. closed Central American Seaway (CAS) from 10 Ma onwards. In the cGENIE model, we explore uncertainty in greenhouse gas forcing and the magnitude of North Pacific to North Atlantic salinity flux adjustment required in the model to create an Atlantic Meridional Overturning Circulation (AMOC) of a specific strength, via a series of 12 (one for each tectonic reconstruction) 2D parameter ensembles. Each ensemble member is then tested against the observed global temperature and benthic δ13C patterns. We identify that a relatively high CO2 equivalent forcing of 1120 ppm is required at 15 Ma in cGENIE to reproduce proxy temperature estimates in the model, noting that this CO2 forcing is dependent on the cGENIE model's climate sensitivity and that it incorporates the effects of all greenhouse gases. We find that reproducing the observed long-term cooling trend requires a progressively declining greenhouse gas forcing in the model. In parallel to this, the strength of the AMOC increases with time despite a reduction in the salinity of the surface North Atlantic over the cooling period, attributable to falling intensity of the hydrological cycle and to lowering polar temperatures, both caused by CO2-driven global cooling. We also find that a closed CAS from 10 Ma to present shows better agreement between benthic δ13C patterns and our particular series of model configurations and data. A final outcome of our analysis is a pronounced ca. 1.5 ‰ decline occurring in atmospheric (and ca. 1 ‰ ocean surface) δ13C that could be used to inform future δ13C-based proxy reconstructions.

scholarly journals Multiphase processes in the EC-Earth Earth System model and their relevance to the atmospheric oxalate, sulfate, and iron cycles

2021 ◽  
Author(s):  
Stelios Myriokefalitakis ◽  
Elisa Bergas-Massó ◽  
María Gonçalves-Ageitos ◽  
Carlos Pérez García-Pando ◽  
Twan van Noije ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Aqueous Phase ◽  
Earth System Model ◽  
System Model ◽  
Atmospheric Composition ◽  
Global Ocean ◽  
Deposition Flux ◽  
Earth System ◽  
Sulfate Production ◽  
Phase Chemistry

Abstract. Understanding how multiphase processes affect the iron-containing aerosol cycle is key to predict ocean biogeochemistry changes and hence the feedback effects on climate. For this work, the EC-Earth Earth system model in its climate-chemistry configuration is used to simulate the global atmospheric oxalate (OXL), sulfate (SO42−), and iron (Fe) cycles, after incorporating a comprehensive representation of the multiphase chemistry in cloud droplets and aerosol water. The model considers a detailed gas-phase chemistry scheme, all major aerosol components, and the partitioning of gases in aerosol and atmospheric water phases. The dissolution of Fe-containing aerosols accounts kinetically for the solution’s acidity, oxalic acid, and irradiation. Aerosol acidity is explicitly calculated in the model, both for accumulation and coarse modes, accounting for thermodynamic processes involving inorganic and crustal species from sea salt and dust. Simulations for present-day conditions (2000–2014) have been carried out with both EC-Earth and the atmospheric composition component of the model in standalone mode driven by meteorological fields from ECMWF’s ERA-Interim reanalysis. The calculated global budgets are presented and the links between the 1) aqueous-phase processes, 2) aerosol dissolution, and 3) atmospheric composition, are demonstrated and quantified. The model results are supported by comparison to available observations. We obtain an average global OXL net chemical production of 12.61 ± 0.06 Tg yr−1 in EC-Earth, with glyoxal being by far the most important precursor of oxalic acid. In comparison to the ERA-Interim simulation, differences in atmospheric dynamics as well as the simulated weaker oxidizing capacity in EC-Earth result overall in a ~30 % lower OXL source. On the other hand, the more explicit representation of the aqueous-phase chemistry in EC-Earth compared to the previous versions of the model leads to an overall ~20 % higher sulfate production, but still well correlated with atmospheric observations. The total Fe dissolution rate in EC-Earth is calculated at 0.806 ± 0.014 Tg Fe yr−1 and is added to the primary dissolved Fe (DFe) sources from dust and combustion aerosols in the model (0.072 ± 0.001 Tg Fe yr−1). The simulated DFe concentrations show a satisfactory comparison with available observations, indicating an atmospheric burden of ∼0.007 Tg Fe, and overall resulting in an atmospheric deposition flux into the global ocean of 0.376 ± 0.005 Tg Fe yr−1, well within the range reported in the literature. All in all, this work is a first step towards the development of EC-Earth into an Earth System Model with fully interactive bioavailable atmospheric Fe inputs to the marine biogeochemistry component of the model.

scholarly journals EcoGEnIE 0.1: Plankton Ecology in the cGENIE Earth system model

2017 ◽  
Author(s):  
Ben A. Ward ◽  
Jamie D. Wilson ◽  
Ros M. Death ◽  
Fanny M. Monteiro ◽  
Andrew Yool ◽  
...  
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Global Scale ◽  
Earth System Model ◽  
Marine Ecology ◽  
System Model ◽  
Global Ocean ◽  
Earth System ◽  
Ocean Ecosystem ◽  
Global Biogeochemical Cycles ◽  
Plankton Species

Abstract. We present an extension to the cGENIE Earth System model that explicitly accounts for the growth and interaction of an arbitrary number of plankton species. The new package (ECOGEM) replaces the implicit, flux-based, parameterisation of the plankton community currently employed, with explicitly resolved plankton populations and ecological dynamics. In ECOGEM, any number of plankton species, with ecophysiological traits (e.g. growth and grazing rates) assigned according to organism size and functional group (e.g. phytoplankton and zooplankton) can be incorporated at run-time. We illustrate the capability of the marine ecology enabled Earth system model (EcoGENIE) by comparing results from one configuration of ECOGEM (with eight generic phytoplankton and zooplankton size classes) to climatological and seasonal observations. We find that the new ecological components of the model show reasonable agreement with both global-scale climatological and local-scale seasonal data. We also compare EcoGENIE results to a the existing biogeochemical incarnation of cGENIE. We find that the resulting global-scale distributions of phosphate, iron, dissolved inorganic carbon, alkalinity and oxygen are similar for both iterations of the model. A slight deterioration in some fields in EcoGENIE (relative to the data) is observed, although we make no attempt to re-tune the overall marine cycling of carbon and nutrients here. The increased capabilities of EcoGENIE in this regard will enable future exploration of the ecological community on much longer timescales than have previously been examined in global ocean ecosystem models and particularly for past climates and global biogeochemical cycles.

scholarly journals EcoGEnIE 1.0: plankton ecology in the cGEnIE Earth system model

2018 ◽  
Vol 11 (10) ◽  
pp. 4241-4267 ◽  
Author(s):  
Ben A. Ward ◽  
Jamie D. Wilson ◽  
Ros M. Death ◽  
Fanny M. Monteiro ◽  
Andrew Yool ◽  
...  
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Global Scale ◽  
Earth System Model ◽  
Marine Ecology ◽  
System Model ◽  
Global Ocean ◽  
Earth System ◽  
Ocean Ecosystem ◽  
Global Biogeochemical Cycles ◽  
Plankton Species

Abstract. We present an extension to the carbon-centric Grid Enabled Integrated Earth system model (cGEnIE) that explicitly accounts for the growth and interaction of an arbitrary number of plankton species. The new package (ECOGEM) replaces the implicit, flux-based parameterisation of the plankton community currently employed, with explicitly resolved plankton populations and ecological dynamics. In ECOGEM, any number of plankton species, with ecophysiological traits (e.g. growth and grazing rates) assigned according to organism size and functional group (e.g. phytoplankton and zooplankton) can be incorporated at runtime. We illustrate the capability of the marine ecology enabled Earth system model (EcoGEnIE) by comparing results from one configuration of ECOGEM (with eight generic phytoplankton and zooplankton size classes) to climatological and seasonal observations. We find that the new ecological components of the model show reasonable agreement with both global-scale climatological and local-scale seasonal data. We also compare EcoGEnIE results to the existing biogeochemical incarnation of cGEnIE. We find that the resulting global-scale distributions of phosphate, iron, dissolved inorganic carbon, alkalinity, and oxygen are similar for both iterations of the model. A slight deterioration in some fields in EcoGEnIE (relative to the data) is observed, although we make no attempt to re-tune the overall marine cycling of carbon and nutrients here. The increased capabilities of EcoGEnIE in this regard will enable future exploration of the ecological community on much longer timescales than have previously been examined in global ocean ecosystem models and particularly for past climates and global biogeochemical cycles.

scholarly journals P-CSI v1.0, an accelerated barotropic solver for the high-resolution ocean model component in the Community Earth System Model v2.0

2016 ◽  
Vol 9 (11) ◽  
pp. 4209-4225 ◽  
Author(s):  
Xiaomeng Huang ◽  
Qiang Tang ◽  
Yuheng Tseng ◽  
Yong Hu ◽  
Allison H. Baker ◽  
...  
Keyword(s):  
High Resolution ◽  
Ocean Model ◽  
Original Method ◽  
Earth System Model ◽  
System Model ◽  
Global Ocean ◽  
Global Communication ◽  
Earth System ◽  
Communication Time ◽  
Community Earth System Model

Abstract. In the Community Earth System Model (CESM), the ocean model is computationally expensive for high-resolution grids and is often the least scalable component for high-resolution production experiments. The major bottleneck is that the barotropic solver scales poorly at high core counts. We design a new barotropic solver to accelerate the high-resolution ocean simulation. The novel solver adopts a Chebyshev-type iterative method to reduce the global communication cost in conjunction with an effective block preconditioner to further reduce the iterations. The algorithm and its computational complexity are theoretically analyzed and compared with other existing methods. We confirm the significant reduction of the global communication time with a competitive convergence rate using a series of idealized tests. Numerical experiments using the CESM 0.1° global ocean model show that the proposed approach results in a factor of 1.7 speed-up over the original method with no loss of accuracy, achieving 10.5 simulated years per wall-clock day on 16 875 cores.

Emergent constraints on the Southern Ocean anthropogenic carbon and heat uptake

2021 ◽  
Author(s):  
Thomas Frölicher ◽  
Jens Terhaar ◽  
Fortunat Joos
Keyword(s):  
Southern Ocean ◽  
Ocean Circulation ◽  
Earth System Model ◽  
System Model ◽  
Carbon Uptake ◽  
Earth System ◽  
Excess Heat ◽  
The Past ◽  
Heat Uptake ◽  
Anthropogenic Carbon

<p>The Southern Ocean south of 30°S, occupying about a third of global surface ocean area, accounts for approximately 40% of the past anthropogenic carbon uptake and about 75% of excess heat uptake by the ocean. However, Earth system models have large difficulties in reproducing the Southern Ocean circulation, and therefore its historical and future anthropogenic carbon and excess heat uptake. In the first part of the talk, we show that there exists a tight relation across two Earth system model ensembles (CMIP5 and CMIP6) between present-day sea surface salinity in the subtropical-polar frontal zone, the formation region of mode and intermediate waters, and the past and future anthropogenic carbon uptake in the Southern Ocean. By using observations and Earth system model results, we constrain the projected cumulative Southern Ocean anthropogenic carbon uptake over 1850-2100 by the CMIP6 model ensemble to 158 ± 6 Pg C under the low-emissions scenario SSP1-2.6 and to 279 ± 14 Pg C under the high emissions scenario SSP5-8.5. Our results suggest that the Southern Ocean anthropogenic carbon sink is 14-18% larger and 46-54% less uncertain than estimated by the unconstrained CMIP6 Earth system model results. The identified constraint demonstrated the importance of the freshwater cycle for the Southern Ocean circulation and carbon cycle. In the second part of the talk, potential emergent constraints for the Southern Ocean excess heat uptake will be discussed.</p>

scholarly journals The Mechanistic Role of the Central American Seaway in a GFDL Earth System Model. Part 1: Impacts on Global Ocean Mean State and Circulation

2018 ◽  
Vol 33 (7) ◽  
pp. 840-859 ◽  
Author(s):  
Lori T. Sentman ◽  
John P. Dunne ◽  
Ronald J. Stouffer ◽  
John P. Krasting ◽  
J. R. Toggweiler ◽  
...  
Keyword(s):  
Earth System Model ◽  
Central American ◽  
System Model ◽  
Global Ocean ◽  
Earth System ◽  
Central American Seaway ◽  
Mean State

scholarly journals <sup>231</sup>Pa and <sup>230</sup>Th in the ocean model of the Community Earth System Model (CESM1.3)

2017 ◽  
Vol 10 (12) ◽  
pp. 4723-4742 ◽  
Author(s):  
Sifan Gu ◽  
Zhengyu Liu
Keyword(s):  
Ocean Circulation ◽  
Activity Ratio ◽  
Marine Ecosystem ◽  
Deep Ocean ◽  
Ocean Model ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Direct Model ◽  
Community Earth System Model

Abstract. The sediment 231Pa ∕ 230Th activity ratio is emerging as an important proxy for deep ocean circulation in the past. In order to allow for a direct model–data comparison and to improve our understanding of the sediment 231Pa ∕ 230Th activity ratio, we implement 231Pa and 230Th in the ocean component of the Community Earth System Model (CESM). In addition to the fully coupled implementation of the scavenging behavior of 231Pa and 230Th with the active marine ecosystem module (particle-coupled: hereafter p-coupled), another form of 231Pa and 230Th have also been implemented with prescribed particle flux fields of the present climate (particle-fixed: hereafter p-fixed). The comparison of the two forms of 231Pa and 230Th helps to isolate the influence of the particle fluxes from that of ocean circulation. Under present-day climate forcing, our model is able to simulate water column 231Pa and 230Th activity and the sediment 231Pa ∕ 230Th activity ratio in good agreement with available observations. In addition, in response to freshwater forcing, the p-coupled and p-fixed sediment 231Pa ∕ 230Th activity ratios behave similarly over large areas of low productivity on long timescales, but can differ substantially in some regions of high productivity and on short timescales, indicating the importance of biological productivity in addition to ocean transport. Therefore, our model provides a potentially powerful tool to help the interpretation of sediment 231Pa ∕ 230Th reconstructions and to improve our understanding of past ocean circulation and climate changes.

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