scholarly journals Processes Controlling Arctic and Antarctic Sea Ice Predictability in the Community Earth System Model

2018 ◽  
Vol 31 (23) ◽  
pp. 9771-9786 ◽  
Author(s):  
Ana C. Ordoñez ◽  
Cecilia M. Bitz ◽  
Edward Blanchard-Wrigglesworth
Keyword(s):  
Sea Ice ◽  
Mixed Layer ◽  
Ocean Dynamics ◽  
System Model ◽  
The Arctic ◽  
Earth System ◽  
Ice Volume ◽  
Antarctic Sea Ice ◽  
The Antarctic ◽  
Area And Volume

Sea ice predictability is a rapidly growing area of research, with most studies focusing on the Arctic. This study offers new insights by comparing predictability between the Arctic and Antarctic sea ice anomalies, focusing on the effects of regional differences in ice thickness and ocean dynamics. Predictability in simulated regional sea ice area and volume is investigated in long control runs of an Earth system model. Sea ice area predictability in the Arctic agrees with results from other studies, with features of decaying initial persistence and reemergence because of ocean mixed layer processes and memory in thick ice. In pan-Arctic averages, sea ice volume and the area covered by thick ice are the best predictors of September area for lead times greater than 2 months. In the Antarctic, area is generally the best predictor of future area for all times of year. Predictability of area in summer differs between the hemispheres because of unique aspects of the coupling between area and volume. Generally, ice volume only adds to the predictability of summer sea ice area in the Arctic. Predictability patterns vary greatly among different regions of the Arctic but share similar seasonality among regions of the Antarctic. Interactive ocean dynamics influence anomaly reemergence differently in the Antarctic than the Arctic, both for the total and regional area. In the Antarctic, ocean dynamics generally decrease the persistence of area anomalies, reducing predictability. In the Arctic, the presence of ocean dynamics improves ice area predictability, mainly through mixed layer depth variability.

Arctic connections between sea ice, ocean dynamics and biogeochemistry in the UK Earth System Model (UK ESM1): present climate and future scenarios

2020 ◽  
Author(s):  
Yevgeny Aksenov ◽  
Andrew Yool ◽  
Julien Palmieri ◽  
Katya Popova ◽  
Stephen Kelly ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Arctic Sea Ice ◽  
Ocean Dynamics ◽  
System Model ◽  
The Arctic ◽  
Earth System ◽  
Present Climate ◽  
Arctic Sea ◽  
The Uk

<p>We present analysis of Arctic sea ice and ocean dynamics in the ensemble of the UK Earth System Model (UK ESM1) simulations completed under the Coupled Model Intercomparison Project Phase 6 (CMIP6) protocol. The focus of the investigation is on the future changes in the Arctic sea ice and oceanic connections and on the impact of the nutrient advection on the Arctic marine biogeochemistry and ecosystems. Changes in the balance of the oceanic inflows from the North Atlantic and North Pacific Oceans are found to have a first order effect on the watermasses and nutrients balances in the central Arctic Ocean. The simulations show that the total primary production in the Arctic Ocean is increased by 100% in the 2090s as compared to the present climate. This is caused by higher nutrients availability in the Atlantic inflowing waters and prolonged ice- free season. The faster connections through the Arctic and milder oceanic environment allows species to survive through the winter and from the second half of the century the Arctic Ocean could become a key oceanic gateway connecting the global oceans. The study is supported from the project APEAR (NE/R012865/1) NERC-BMBF and from the NERC ACSIS Programme (NE/N018044/1).</p>

Aerosols and their impacts on future Arctic climate change under different emission projections in the GISS-E2.1 Earth system model

2021 ◽  
Author(s):  
Ulas Im ◽  
Kostas Tsigaridis ◽  
Gregory S. Faluvegi ◽  
Peter L. Langen ◽  
Joshua P. French ◽  
...  
Keyword(s):  
Sea Ice ◽  
Earth System Model ◽  
System Model ◽  
The Arctic ◽  
Earth System ◽  
Anthropogenic Aerosols ◽  
Emission Reductions ◽  
Air Temperatures ◽  
The Future ◽  
Emission Projections

<p>In order to study the future aerosol burdens and their radiative and climate impacts over the Arctic (>60 °N), future (2015-2050) simulations have been carried out using the GISS-E2.1 Earth system model. Different future anthrpogenic emission projections have been used from the Eclipse V6b and the Coupled Model Intercomparison Project Phase 6 (CMIP6) databases. Results showed that Arctic BC, OC and SO<sub>4</sub><sup>2-</sup> burdens decrease significantly in all simulations following the emission projections, with the CMIP6 ensemble showing larger reductions in Arctic aerosol burdens compared to the Eclipse ensemble. For the 2030-2050 period, both the Eclipse Current Legislation (CLE) and the Maximum Feasible Reduction (MFR) ensembles simulated an aerosol top of the atmosphere (TOA) forcing of -0.39±0.01 W m<sup>-2</sup>, of which -0.24±0.01 W m<sup>-2</sup> were attributed to the anthropogenic aerosols. The CMIP6 SSP3-7.0 scenario simulated a TOA aerosol forcing of -0.35 W m<sup>-2</sup> for the same period, while SSP1-2.6 and SSP2-4.5 scenarios simulated a slightly more negative TOA forcing (-0.40 W m<sup>-2</sup>), of which the anthropogenic aerosols accounted for -0.26 W m<sup>-2</sup>. The 2030-2050 mean surface air temperatures are projected to increase by 2.1 °C and 2.4 °C compared to the 1990-2010 mean temperature according to the Eclipse CLE and MFR ensembles, respectively, while the CMIP6 simulation calculated an increase of 1.9 °C (SSP1-2.6) to 2.2 °C (SSP3-7.0). Overall, results show that even the scenarios with largest emission reductions lead to similar impact on the future Arctic surface air temperatures compared to scenarios with smaller emission reductions, while scenarios with no or little mitigation leads to much larger sea-ice loss, implying that even though the magnitude of aerosol reductions lead to similar responses in surface air temperatures, high mitigation of aerosols are still necessary to limit sea-ice loss. </p>

scholarly journals The Arctic and Antarctic Sea-Ice Area Index Records versus Measured and Modeled Temperature Data

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Nicola Scafetta ◽  
Adriano Mazzarella
Keyword(s):  
Sea Ice ◽  
General Circulation ◽  
General Circulation Models ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Climate Indices ◽  
Area Index ◽  
Antarctic Sea Ice ◽  
Arctic Sea ◽  
The Antarctic

Here we study the Arctic and Antarctic sea-ice area records provided by the National Snow and Ice Data Center (NSIDC). These records reveal an opposite climatic behavior: since 1978 the Arctic sea-ice area index decreased, that is, the region has warmed, while the Antarctic sea-ice area index increased, that is, the region has cooled. During the last 7 years the Arctic sea-ice area has stabilized while the Antarctic sea-ice area has increased at a rate significantly higher than during the previous decades; that is, the sea-ice area of both regions has experienced a positive acceleration. This result is quite robust because it is confirmed by alternative temperature climate indices of the same regions. We also found that a significant 4-5-year natural oscillation characterizes the climate of these sea-ice polar areas. On the contrary, we found that the CMIP5 general circulation models have predicted significant warming in both polar sea regions and failed to reproduce the strong 4-5-year oscillation. Because the CMIP5 GCM simulations are inconsistent with the observations, we suggest that important natural mechanisms of climate change are missing in the models.

scholarly journals Evaluation and climate sensitivity of the PlaSim v.17 Earth System Model coupled with ocean model components of different complexity

2020 ◽  
Author(s):  
Michela Angeloni ◽  
Elisa Palazzi ◽  
Jost von Hardenberg
Keyword(s):  
Sea Ice ◽  
Heat Transport ◽  
Mixed Layer ◽  
Climate Sensitivity ◽  
Ice Cover ◽  
Earth System Model ◽  
Sea Surface ◽  
System Model ◽  
Earth System ◽  
Feedback Mechanisms

Abstract. A set of experiments is performed with coupled atmosphere-ocean configurations of the Planet Simulator, an Earth-system Model of Intermediate Complexity (EMIC), in order to identify under which set of parameters the model output better agrees with observations and reanalyses of the present climate. Different model configurations are explored, in which the atmospheric module of PlaSim is coupled with two possible ocean models, either a simple mixed-layer (ML) ocean with a diffusive transport parameterization or a more complex dynamical Large-Scale Geostrophic (LSG) ocean, together with a sea-ice module. In order to achieve a more realistic representation of present-day climate, we performed a preliminary tuning of the oceanic horizontal diffusion coefficient for the ML ocean and of the vertical oceanic diffusion profile when using LSG. Model runs under present-day conditions are compared, in terms of surface air temperature, sea surface temperature, sea ice cover, precipitation, radiation fluxes, ocean circulation, with a reference climate from observations and reanalyses. Our results indicate that, in all configurations, coupled PlaSim configurations are able to reproduce the main characteristics of the climate system, with the exception of the Southern Ocean region in the PlaSim-LSG model, where surface air and sea surface temperatures are warm-biased and sea ice cover is by consequence highly underestimated. The resulting sets of tuned parameters are used to perform a series of model equilibrium climate sensitivity (ECS) experiments, with the aim to identify the main mechanisms contributing to differences between the different configurations and leading to elevated values of ECS. In fact, high resulting global ECS values are found, positioned in the upper range of CMIP5 and recent CMIP6 estimates. Our analysis shows that a significant contribution to ECS is given by the sea-ice feedback mechanisms and by details of the parameterization of meridional oceanic heat transport. In particular, the configurations using a diffusive heat transport in the mixed layer present an important sensitivity in terms of radiative forcing to changes in sea-ice cover, leading to an important contribution of sea-ice feedback mechanisms to ECS.

scholarly journals Comparison of sea ice kinematics at different resolutions modeled with a grid hierarchy in the Community Earth System Model (version 1.2.1)

2021 ◽  
Vol 14 (1) ◽  
pp. 603-628
Author(s):  
Shiming Xu ◽  
Jialiang Ma ◽  
Lu Zhou ◽  
Yan Zhang ◽  
Jiping Liu ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Ice ◽  
Earth System Model ◽  
System Model ◽  
The Arctic ◽  
Small Scale ◽  
Earth System ◽  
Atmospheric Circulation Patterns ◽  
Community Earth System Model ◽  
Climate Studies

Abstract. High-resolution sea ice modeling is becoming widely available for both operational forecasts and climate studies. In traditional Eulerian grid-based models, small-scale sea ice kinematics represent the most prominent feature of high-resolution simulations, and with rheology models such as viscous–plastic (VP) and Maxwell elasto-brittle (MEB), sea ice models are able to reproduce multi-fractal sea ice deformation and linear kinematic features that are seen in high-resolution observational datasets. In this study, we carry out modeling of sea ice with multiple grid resolutions by using the Community Earth System Model (CESM) and a grid hierarchy (22, 7.3, and 2.4 km grid stepping in the Arctic). By using atmospherically forced experiments, we simulate consistent sea ice climatology across the three resolutions. Furthermore, the model reproduces reasonable sea ice kinematics, including multi-fractal spatial scaling of sea ice deformation that partially depends on atmospheric circulation patterns and forcings. By using high-resolution runs as references, we evaluate the model's effective resolution with respect to the statistics of sea ice kinematics. Specifically, we find the spatial scale at which the probability density function (PDF) of the scaled sea ice deformation rate of low-resolution runs matches that of high-resolution runs. This critical scale is treated as the effective resolution of the coarse-resolution grid, which is estimated to be about 6 to 7 times the grid's native resolution. We show that in our model, the convergence of the elastic–viscous–plastic (EVP) rheology scheme plays an important role in reproducing reasonable kinematics statistics and, more strikingly, simulates systematically thinner sea ice than the standard, non-convergent experiments in landfast ice regions of the Canadian Arctic Archipelago. Given the wide adoption of EVP and subcycling settings in current models, it highlights the importance of EVP convergence, especially for climate studies and projections. The new grids and the model integration in CESM are openly provided for public use.

scholarly journals Multi-Scale Sea Ice Kinematics Modeling with a Grid Hierarchy in Community Earth System Model (version 1.2.1)

2020 ◽  
Author(s):  
Shiming Xu ◽  
Jialiang Ma ◽  
Lu Zhou ◽  
Yan Zhang ◽  
Jiping Liu ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Ice ◽  
Earth System Model ◽  
System Model ◽  
The Arctic ◽  
Earth System ◽  
Multi Scale ◽  
Kinematics Modeling ◽  
Community Earth System Model ◽  
Climate Studies

Abstract. High-resolution sea ice modeling is becoming widely available for both operational forecasts and climate studies. Sea ice kinematics is the most prominent feature of high-resolution simulations, and with rheology models such as Viscous-Plastic, current models are able to reproduce multi-fractality and linear kinematic features in satellite observations. In this study, we carry out multi-scale sea ice modeling with Community Earth System Model (CESM) by using a grid hierarchy (22 km, 7.3 km, and 2.5 km grid stepping in the Arctic). By using atmospherically forced experiments, we simulate consistent sea ice climatology across the 3 resolutions. Furthermore, the model reproduces reasonable sea ice kinematics, including multi-fractal deformation and scaling properties that are temporally changing and dependent on circulation patterns and forcings (e.g., Arctic Oscillation). With the grid hierarchy, we are able to evaluate the model's effective spatial resolution regarding the statistics of kinematics, which is estimated to be about 6 to 7 times that of the grid's native resolution. Besides, we show that in our model, the convergence of the Elastic-Viscous-Plastic (EVP) rheology scheme plays an important role in reproducing reasonable kinematics statistics, and more strikingly, simulates systematically thinner sea ice than the standard, non-convergent experiments in landfast ice regions of Canadian Arctic Archipelago. Given the wide adoption of EVP and subcycling settings in current models, it highlights the importance of EVP convergence especially for climate studies and projections. The new grids and the model integration in CESM are openly provided for public use.

scholarly journals A Regime Shift in Seasonal Total Antarctic Sea Ice Extent in the 20th Century

2021 ◽  
Author(s):  
Ryan Fogt ◽  
Amanda Sleinkofer ◽  
Marilyn Raphael ◽  
Mark Handcock
Keyword(s):  
Sea Ice ◽  
20Th Century ◽  
Climate Models ◽  
Historical Context ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice ◽  
Coupled Climate Models ◽  
High Degree ◽  
The Antarctic

Abstract In stark contrast to the Arctic, there have been statistically significant positive trends in total Antarctic sea ice extent since 1979, despite a sudden decline in sea ice in 2016(1–5) and increasing greenhouse gas concentrations. Attributing Antarctic sea ice trends is complicated by the fact that most coupled climate models show negative trends in sea ice extent since 1979, opposite of that observed(6–8). Additionally, the short record of sea ice extent (beginning in 1979), coupled with the high degree of interannual variability, make the record too short to fully understand the historical context of these recent changes(9). Here we show, using new robust observation-based reconstructions, that 1) these observed recent increases in Antarctic sea ice extent are unique in the context of the 20th century and 2) the observed trends are juxtaposed against statistically significant decreases in sea ice extent throughout much of the early and middle 20th century. These reconstructions are the first to provide reliable estimates of total sea ice extent surrounding the continent; previous proxy-based reconstructions are limited(10). Importantly, the reconstructions continue to show the high degree of interannual Antarctic sea ice extent variability that is marked with frequent sudden changes, such as observed in 2016, which stress the importance of a longer historical context when assessing and attributing observed trends in Antarctic climate(9). Our reconstructions are skillful enough to be used in climate models to allow better understanding of the interconnected nature of the Antarctic climate system and to improve predictions of the future state of Antarctic climate.

The Interplay of Recent Vegetation and Sea Ice Dynamics—Results From a Regional Earth System Model Over the Arctic

2020 ◽  
Vol 47 (6) ◽  
Author(s):  
W. Zhang ◽  
R. Döscher ◽  
T. Koenigk ◽  
P.A. Miller ◽  
C. Jansson ◽  
...  
Keyword(s):  
Sea Ice ◽  
Earth System Model ◽  
System Model ◽  
The Arctic ◽  
Earth System ◽  
Ice Dynamics ◽  
Sea Ice Dynamics

Sensitivity of organic carbon fluxes from Arctic coastal erosion to climate change

2021 ◽  
Author(s):  
David Marcolino Nielsen ◽  
Patrick Pieper ◽  
Victor Brovkin ◽  
Paul Overduin ◽  
Tatiana Ilyina ◽  
...  
Keyword(s):  
Climate Change ◽  
Organic Carbon ◽  
Sea Ice ◽  
Coastal Erosion ◽  
Earth System Model ◽  
System Model ◽  
The Arctic ◽  
Earth System ◽  
Carbon Release ◽  
Arctic Coast

<p>When unprotected by sea-ice and exposed to the warm air and ocean waves, the Arctic coast erodes and releases organic carbon from permafrost to the surrounding ocean and atmosphere. This release is estimated to deliver similar amounts of organic carbon to the Arctic Ocean as all Arctic rivers combined, at the present-day climate. Depending on the degradation pathway of the eroded material, the erosion of the Arctic coast could represent a positive feedback loop in the climate system, to an extent still unknown. In addition, the organic carbon flux from Arctic coastal erosion is expected to increase in the future, mainly due to surface warming and sea-ice loss. In this work, we aim at addressing the following questions: How is Arctic coastal erosion projected to change in the future? How sensitive is Arctic coastal erosion to climate change?</p><p>To address these questions, we use a 10-member ensemble of climate change simulations performed with the Max Planck Institute Earth System Model (MPI-ESM) for the Coupled Model Intercomparison Project phase 6 (CMIP6) to make projections of coastal erosion at a pan-Arctic scale. We use a semi-empirical approach to model Arctic coastal erosion, assuming a linear contribution of its thermal and mechanical drivers. The pan-Arctic carbon release due to coastal erosion is projected to increase from 6.9 ± 5.4 TgC/year (mean estimate ± two standard deviations from the distribution of uncertainties) during the historical period (mean over 1850 -1950) to between 13.1 ± 6.7 TgC/year and 17.2 ± 8.2 TgC/year in the period 2081-2100 following an intermediate (SSP2.4-5) and a high-end (SSP5.8-5) climate change scenario, respectively. The sensitivity of the organic carbon release from Arctic coastal erosion to climate warming is estimated to range from 1.52 TgC/year/K to 2.79 TgC/year/K depending on the scenario. Our results present the first projections of Arctic coastal erosion, combining observations and Earth system model (ESM) simulations. This allows us to make first-order estimates of sensitivity and feedback magnitudes between Arctic coastal erosion and climate change, which can lay out pathways for future coupled ESM simulations.</p><p> </p>

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