scholarly journals Projected Shifts in 21st Century Sardine Distribution and Catch in the California Current

2021 ◽  
Vol 8 ◽  
Author(s):  
Jerome Fiechter ◽  
Mercedes Pozo Buil ◽  
Michael G. Jacox ◽  
Michael A. Alexander ◽  
Kenneth A. Rose
Keyword(s):  
High Resolution ◽  
21St Century ◽  
Global Climate ◽  
California Current ◽  
Climate Forcing ◽  
Earth System ◽  
System Models ◽  
Sardine Population ◽  
End To End ◽  
Earth System Models

Predicting changes in the abundance and distribution of small pelagic fish species in response to anthropogenic climate forcing is of paramount importance due to the ecological and socioeconomic importance of these species, especially in eastern boundary current upwelling regions. Coastal upwelling systems are notorious for the wide range of spatial (from local to basin) and temporal (from days to decades) scales influencing their physical and biogeochemical environments and, thus, forage fish habitat. Bridging those scales can be achieved by using high-resolution regional models that integrate global climate forcing downscaled from coarser resolution earth system models. Here, “end-to-end” projections for 21st century sardine population dynamics and catch in the California Current system (CCS) are generated by coupling three dynamically downscaled earth system model solutions to an individual-based fish model and an agent-based fishing fleet model. Simulated sardine population biomass during 2000–2100 exhibits primarily low-frequency (decadal) variability, and a progressive poleward shift driven by thermal habitat preference. The magnitude of poleward displacement varies noticeably under lower and higher warming conditions (500 and 800 km, respectively). Following the redistribution of the sardine population, catch is projected to increase by 50–70% in the northern CCS and decrease by 30–70% in the southern and central CCS. However, the late-century increase in sardine abundance (and hence, catch) in the northern CCS exhibits a large ensemble spread and is not statistically identical across the three downscaled projections. Overall, the results illustrate the benefit of using dynamical downscaling from multiple earth system models as input to high-resolution regional end-to-end (“physics to fish”) models for projecting population responses of higher trophic organisms to global climate change.

scholarly journals Analytically tractable climate–carbon cycle feedbacks under 21st century anthropogenic forcing

2018 ◽  
Vol 9 (2) ◽  
pp. 507-523 ◽  
Author(s):  
Steven J. Lade ◽  
Jonathan F. Donges ◽  
Ingo Fetzer ◽  
John M. Anderies ◽  
Christian Beer ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Global Climate ◽  
Future Climate Change ◽  
Earth System ◽  
Co2 Solubility ◽  
Carbon Cycle Model ◽  
Ocean Climate ◽  
System Models ◽  
Analytical Expressions ◽  
Earth System Models

Abstract. Changes to climate–carbon cycle feedbacks may significantly affect the Earth system's response to greenhouse gas emissions. These feedbacks are usually analysed from numerical output of complex and arguably opaque Earth system models. Here, we construct a stylised global climate–carbon cycle model, test its output against comprehensive Earth system models, and investigate the strengths of its climate–carbon cycle feedbacks analytically. The analytical expressions we obtain aid understanding of carbon cycle feedbacks and the operation of the carbon cycle. Specific results include that different feedback formalisms measure fundamentally the same climate–carbon cycle processes; temperature dependence of the solubility pump, biological pump, and CO2 solubility all contribute approximately equally to the ocean climate–carbon feedback; and concentration–carbon feedbacks may be more sensitive to future climate change than climate–carbon feedbacks. Simple models such as that developed here also provide workbenches for simple but mechanistically based explorations of Earth system processes, such as interactions and feedbacks between the planetary boundaries, that are currently too uncertain to be included in comprehensive Earth system models.

Anticipating the computational performance of Earth System Models for pre-exascale systems

2021 ◽  
Author(s):  
Xavier Yepes-Arbós ◽  
Miguel Castrillo ◽  
Mario C. Acosta ◽  
Kim Serradell
Keyword(s):  
Computational Efficiency ◽  
Climate Model ◽  
Global Climate ◽  
Horizontal Resolution ◽  
Limiting Factor ◽  
Earth System ◽  
Computational Point ◽  
System Models ◽  
Computational Performance ◽  
Earth System Models

<p>The increase in the capability of Earth System Models (ESMs) is strongly linked to the amount of computing power, given that the spatial resolution used for global climate experimentation is a limiting factor to correctly reproduce climate mean state and variability. However, higher spatial resolutions require new High Performance Computing (HPC) platforms, where the improvement of the computational efficiency of ESMs will be mandatory. In this context, porting a new ultra-high resolution configuration into a new and more powerful HPC cluster is a challenging task, involving technical expertise to deploy and improve the computational performance of such a novel configuration.</p><p>To take advantage of this foreseeable landscape, the new EC-Earth 4 climate model is being developed by coupling OpenIFS 43R3 and NEMO 4 as atmosphere and ocean components respectively. An important effort has been made to improve the computational efficiency of this new EC-Earth version, such as extending the asynchronous I/O capabilities of the XIOS server to OpenIFS. </p><p>In order to anticipate the computational behaviour of EC-Earth 4 for new pre-exascale machines such as the upcoming MareNostrum 5 of the Barcelona Supercomputing Center (BSC), OpenIFS and NEMO models are therefore benchmarked on a petascale machine (MareNostrum 4) to find potential computational bottlenecks introduced by new developments or to investigate if previous known performance limitations are solved. The outcome of this work can also be used to efficiently set up new ultra-high resolutions from a computational point of view, not only for EC-Earth, but also for other ESMs.</p><p>Our benchmarking consists of large strong scaling tests (tens of thousands of cores) by running different output configurations, such as changing multiple XIOS parameters and number of 2D and 3D fields. These very large tests need a huge amount of computational resources (up to 2,595 nodes, 75 % of the supercomputer), so they require a special allocation that can be applied once a year.</p><p>OpenIFS is evaluated with a 9 km global horizontal resolution (Tco1279) and using three different output data sets: no output, CMIP6-based fields and huge output volume (8.8 TB) to stress the I/O part. In addition, different XIOS parameters, XIOS resources, affinity, MPI-OpenMP hybridisation and MPI library are tested. Results suggest new features introduced in 43R3 do not represent a bottleneck in terms of performance as the model scales. The I/O scheme is also improved when outputting data through XIOS according to the scalability curve.</p><p>NEMO is scaled using a 3 km global horizontal resolution (ORCA36) with and without the sea-ice module. As in OpenIFS, different I/O configurations are benchmarked, such as disabling model output, only enabling 2D fields, or either producing 3D variables on an hourly basis. XIOS is also scaled and tested with different parameters. While NEMO has good scalability during the most part of the exercise, a severe degradation is observed before the model uses 70% of the machine resources (2,546 nodes). The I/O overhead is moderate for the best XIOS configuration, but it demands many resources.</p>

scholarly journals An Overview of CMIP5 and the Experiment Design

2012 ◽  
Vol 93 (4) ◽  
pp. 485-498 ◽  
Author(s):  
Karl E. Taylor ◽  
Ronald J. Stouffer ◽  
Gerald A. Meehl
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Global Climate ◽  
Experiment Design ◽  
Global Climate Models ◽  
Model Output ◽  
Earth System ◽  
Intergovernmental Panel ◽  
System Models ◽  
Earth System Models

The fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance our knowledge of climate variability and climate change. Researchers worldwide are analyzing the model output and will produce results likely to underlie the forthcoming Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Unprecedented in scale and attracting interest from all major climate modeling groups, CMIP5 includes “long term” simulations of twentieth-century climate and projections for the twenty-first century and beyond. Conventional atmosphere–ocean global climate models and Earth system models of intermediate complexity are for the first time being joined by more recently developed Earth system models under an experiment design that allows both types of models to be compared to observations on an equal footing. Besides the longterm experiments, CMIP5 calls for an entirely new suite of “near term” simulations focusing on recent decades and the future to year 2035. These “decadal predictions” are initialized based on observations and will be used to explore the predictability of climate and to assess the forecast system's predictive skill. The CMIP5 experiment design also allows for participation of stand-alone atmospheric models and includes a variety of idealized experiments that will improve understanding of the range of model responses found in the more complex and realistic simulations. An exceptionally comprehensive set of model output is being collected and made freely available to researchers through an integrated but distributed data archive. For researchers unfamiliar with climate models, the limitations of the models and experiment design are described.

scholarly journals Changes in interannual climate sensitivities of terrestrial carbon fluxes during the 21st century predicted by CMIP5 Earth System Models

2016 ◽  
Vol 121 (3) ◽  
pp. 903-918 ◽  
Author(s):  
Yongwen Liu ◽  
Tao Wang ◽  
Mengtian Huang ◽  
Yitong Yao ◽  
Philippe Ciais ◽  
...  
Keyword(s):  
21St Century ◽  
Carbon Fluxes ◽  
Earth System ◽  
Terrestrial Carbon ◽  
System Models ◽  
Earth System Models

scholarly journals Two-way coupling between the sub-grid land surface and river networks in Earth system models

2020 ◽  
Author(s):  
Nathaniel W. Chaney ◽  
Laura Torres-Rojas ◽  
Noemi Vergopolan ◽  
Colby K. Fisher
Keyword(s):  
High Resolution ◽  
Land Surface ◽  
Environmental Data ◽  
Added Value ◽  
Earth System ◽  
Field Scale ◽  
System Models ◽  
Routing Scheme ◽  
Earth System Models ◽  
River Routing

Abstract. Over the past decade, there has been appreciable progress towards modeling the water, energy, and carbon cycles at field-scales (10–100 m) over continental to global extents. One such approach, named HydroBlocks, accomplishes this task while maintaining computational efficiency via sub-grid tiles, or Hydrologic Response Units (HRUs), learned via a hierarchical clustering approach from available global high-resolution environmental data. However, until now, there has yet to be a macroscale river routing approach that is able to leverage HydroBlocks' approach to sub-grid heterogeneity, thus limiting the added value of field-scale land surface modeling in Earth System Models (e.g., riparian zone dynamics, irrigation from surface water, and interactive floodplains). This paper introduces a novel dynamic river routing scheme in HydroBlocks that is intertwined with the modeled field-scale land surface heterogeneity. The primary features of the routing scheme include: 1) the fine-scale river network of each macroscale grid cell's is derived from very high resolution (

scholarly journals Changes in soil organic carbon storage predicted by Earth system models during the 21st century

2013 ◽  
Vol 10 (12) ◽  
pp. 18969-19004 ◽  
Author(s):  
K. E. O. Todd-Brown ◽  
J. T. Randerson ◽  
F. Hopkins ◽  
V. Arora ◽  
T. Hajima ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
21St Century ◽  
Decomposition Rate ◽  
Radiative Forcing ◽  
Atmospheric Carbon Dioxide ◽  
Earth System ◽  
System Models ◽  
Organic Carbon Storage ◽  
Earth System Models

Abstract. Soil is currently thought to be a sink for carbon; however, the response of this sink to increasing levels of atmospheric carbon dioxide and climate change is uncertain. In this study, we analyzed soil organic carbon (SOC) changes from 11 Earth system models (ESMs) under the historical and high radiative forcing (RCP 8.5) scenarios between 1850 and 2100. We used a reduced complexity model based on temperature and moisture sensitivities to analyze the drivers of SOC losses. ESM estimates of SOC change over the 21st century (2090–2099 minus 1997–2006) ranged from a loss of 72 Pg C to a gain 253 Pg C with a multi-model mean gain of 63 Pg C. All ESMs showed cumulative increases in both NPP (15% to 59%) and decreases in SOC turnover times (15% to 28%) over the 21st century. Most of the model-to-model variation in SOC change was explained by initial SOC stocks combined with the relative changes in soil inputs and decomposition rates (R2 = 0.88, p<0.01). Between models, increases in decomposition rate were well explained by a combination of initial decomposition rate, ESM-specific Q10-factors, and changes in soil temperature (R2 = 0.80, p<0.01). All SOC changes depended on sustained increases in NPP with global change (primarily driven by increasing CO2) and conversion of additional plant inputs into SOC. Most ESMs omit potential constraints on SOC storage, such as priming effects, nutrient availability, mineral surface stabilization and aggregate formation. Future models that represent these constraints are likely to estimate smaller increases in SOC storage during the 21st century.

scholarly journals Use of various remote sensing land cover products for PFT mapping over Siberia

2013 ◽  
Vol 6 (1) ◽  
pp. 255-296
Author(s):  
C. Ottlé ◽  
J. Lescure ◽  
F. Maignan ◽  
B. Poulter ◽  
T. Wang ◽  
...  
Keyword(s):  
High Resolution ◽  
Land Cover ◽  
Land Surface ◽  
Land Cover Classification ◽  
Classification Systems ◽  
Tree Cover ◽  
Surface Model ◽  
Earth System ◽  
System Models ◽  
Earth System Models

Abstract. High-latitude ecosystems play an important role in the global carbon cycle and in regulating the climate system and are presently undergoing rapid environmental change. Accurate land cover datasets are required to both document these changes as well as to provide land-surface information for benchmarking and initializing earth system models. Earth system models also require specific land cover classification systems based on plant functional types, rather than species or ecosystems, and so post-processing of existing land cover data is often required. This study compares over Siberia, multiple land cover datasets against one another and with auxiliary data to identify key uncertainties that contribute to variability in Plant Functional Type (PFT) classifications that would introduce errors in earth system modeling. Land cover classification systems from GLC 2000, GlobCover 2005 and 2009, and MODIS collections 5 and 5.1 are first aggregated to a common legend, and then compared to high-resolution land cover classification systems, continuous vegetation fields (MODIS-VCF) and satellite-derived tree heights (to discriminate against sparse, shrub, and forest vegetation). The GlobCover dataset, with a lower threshold for tree cover and taller tree heights and a better spatial resolution, tends to have better distributions of tree cover compared to high-resolution data. It has therefore been chosen to build new PFTs maps for the ORCHIDEE land surface model at 1 km scale. Compared to the original PFT dataset, the new PFT maps based on GlobCover 2005 and an updated cross-walking approach mainly differ in the characterization of forests and degree of tree cover. The partition of grasslands and bare soils now appears more realistic compared with ground-truth data. This new vegetation map provides a framework for further development of new PFTs in the ORCHIDEE model like shrubs, lichens and mosses, to better represent the water and carbon cycles in northern latitudes. Updated land cover datasets are critical for improving and maintaining the relevance of earth system models for assessing climate and human impacts on biogeochemistry and biophysics. The new PFT map at 5 km scale is available for download from the PANGAEA website, at: doi:10.1594/PANGAEA.810709.

scholarly journals ISSM-SESAW v1.0: mesh-based computation of gravitationally consistent sea-level and geodetic signatures caused by cryosphere and climate driven mass change

2016 ◽  
Vol 9 (3) ◽  
pp. 1087-1109 ◽  
Author(s):  
Surendra Adhikari ◽  
Erik R. Ivins ◽  
Eric Larour
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Computational Cost ◽  
Wave Number ◽  
Time Varying ◽  
Earth System ◽  
Viscous Effects ◽  
Legendre Series ◽  
System Models ◽  
Earth System Models

Abstract. A classical Green's function approach for computing gravitationally consistent sea-level variations associated with mass redistribution on the earth's surface employed in contemporary sea-level models naturally suits the spectral methods for numerical evaluation. The capability of these methods to resolve high wave number features such as small glaciers is limited by the need for large numbers of pixels and high-degree (associated Legendre) series truncation. Incorporating a spectral model into (components of) earth system models that generally operate on a mesh system also requires repetitive forward and inverse transforms. In order to overcome these limitations, we present a method that functions efficiently on an unstructured mesh, thus capturing the physics operating at kilometer scale yet capable of simulating geophysical observables that are inherently of global scale with minimal computational cost. The goal of the current version of this model is to provide high-resolution solid-earth, gravitational, sea-level and rotational responses for earth system models operating in the domain of the earth's outer fluid envelope on timescales less than about 1 century when viscous effects can largely be ignored over most of the globe. The model has numerous important geophysical applications. For example, we compute time-varying computations of global geodetic and sea-level signatures associated with recent ice-sheet changes that are derived from space gravimetry observations. We also demonstrate the capability of our model to simultaneously resolve kilometer-scale sources of the earth's time-varying surface mass transport, derived from high-resolution modeling of polar ice sheets, and predict the corresponding local and global geodetic signatures.

Causes of uncertainty in China's net primary production over the 21st century projected by the CMIP5 Earth system models

2015 ◽  
Vol 36 (5) ◽  
pp. 2323-2334 ◽  
Author(s):  
Tao Wang ◽  
Xin Lin ◽  
Yongwen Liu ◽  
Sarah Dantec-Nédélec ◽  
Catherine Ottlé
Keyword(s):  
Primary Production ◽  
21St Century ◽  
Net Primary Production ◽  
Earth System ◽  
System Models ◽  
Earth System Models

scholarly journals Variable phytoplankton size distributions reduce the sensitivity of global export flux to climate change

2020 ◽  
Author(s):  
Shirley W. Leung ◽  
Thomas Weber ◽  
Jacob A. Cram ◽  
Curtis Deutsch
Keyword(s):  
Climate Change ◽  
Particle Size ◽  
Global Climate ◽  
Euphotic Zone ◽  
Nutrient Concentrations ◽  
Biogeochemical Model ◽  
Earth System ◽  
Export Production ◽  
System Models ◽  
Earth System Models

Abstract. Earth System Models predict a 10–20 % decrease in ocean carbon export production by the end of the 21st century due to global climate change. This decline is caused by increased stratification of the upper ocean, resulting in reduced shallow subsurface nutrient concentrations and a slower supply of nutrients to the surface euphotic zone. These predictions, however, do not account for associated changes in sinking particle size and remineralization depth. Here we combine satellite-derived export and particle size maps with a simple 3-D global biogeochemical model to investigate how shifts in sinking particle size may buffer predicted changes in surface nutrient supply and therefore export production. We show that higher export rates are correlated with larger phytoplankton and sinking particles, especially in tropical and subtropical regions. Incorporation of these empirical relationships into a global model shows that as circulation slows, a decrease in export and associated shift toward smaller phytoplankton yields particles that sink more slowly and are thus remineralized shallower; this in turn leads to greater recycling of nutrients in the upper water column and faster nutrient recirculation into the euphotic zone, boosting productivity and export to counteract the initial circulation-driven decreases. This negative feedback mechanism (termed the particle size-remineralization feedback) slows export decline over the next century by ~14 % globally and by ~20 % in the tropical and subtropical oceans, where export decreases are currently predicted to be greatest. Thus, incorporating dynamic particle size-dependent remineralization depths into Earth System Models will result in more robust predictions of changes in biological pump strength in a warming climate.

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