Sea Ice in Coupled Climate Models

Under rising atmospheric greenhouse gas concentrations, the Arctic exhibits amplified warming relative to the globe. This Arctic amplification is a defining feature of global warming. However, the Arctic is also home to large internal variability, which can make the detection of a forced climate response difficult. Here we use results from seven model large ensembles, which have different rates of Arctic warming and sea ice loss, to assess the time of emergence of anthropogenically-forced Arctic amplification. We find that this time of emergence occurs at the turn of the century in all models, ranging across the models by a decade from 1994–2005. We also assess transient changes in this amplified signal across the 21st century and beyond. Over the 21st century, the projections indicate that the maximum Arctic warming will transition from fall to winter due to sea ice reductions that extend further into the fall. Additionally, the magnitude of the annual amplification signal declines over the 21st century associated in part with a weakening albedo feedback strength. In a simulation that extends to the 23rd century, we find that as sea ice cover is completely lost, there is little further reduction in the surface albedo and Arctic amplification saturates at a level that is reduced from its 21st century value.

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

10.21203/rs.3.rs-828060/v1 ◽

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.

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The sea ice mass budget of the Arctic and its future change as simulated by coupled climate models

Climate Dynamics ◽

10.1007/s00382-008-0493-4 ◽

2008 ◽

Vol 34 (2-3) ◽

pp. 185-200 ◽

Cited By ~ 110

Author(s):

Marika M. Holland ◽

Mark C. Serreze ◽

Julienne Stroeve

Keyword(s):

Sea Ice ◽

Climate Models ◽

The Arctic ◽

Future Change ◽

Mass Budget ◽

Coupled Climate Models

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Past and future interannual variability in Arctic sea ice in coupled climate models

The Cryosphere ◽

10.5194/tc-13-113-2019 ◽

2019 ◽

Vol 13 (1) ◽

pp. 113-124 ◽

Cited By ~ 8

Author(s):

John R. Mioduszewski ◽

Stephen Vavrus ◽

Muyin Wang ◽

Marika Holland ◽

Laura Landrum

Keyword(s):

Sea Ice ◽

Climate Models ◽

Coupled Model ◽

Arctic Sea Ice ◽

Cmip5 Models ◽

Coupled Climate Models ◽

Arctic Sea ◽

Ice Retreat ◽

Intercomparison Project ◽

Ice Pack

Abstract. The diminishing Arctic sea ice pack has been widely studied, but previous research has mostly focused on time-mean changes in sea ice rather than on short-term variations that also have important physical and societal consequences. In this study we test the hypothesis that future interannual Arctic sea ice area variability will increase by utilizing 40 independent simulations from the Community Earth System Model's Large Ensemble (CESM-LE) for the 1920–2100 period and augment this with simulations from 12 models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Both CESM-LE and CMIP5 models project that ice area variability will indeed grow substantially but not monotonically in every month. There is also a strong seasonal dependence in the magnitude and timing of future variability increases that is robust among CESM ensemble members. The variability generally correlates with the average ice retreat rate, before there is an eventual disappearance in both terms as the ice pack becomes seasonal in summer and autumn by late century. The peak in variability correlates best with the total area of ice between 0.2 and 0.6 m monthly thickness, indicating that substantial future thinning of the ice pack is required before variability maximizes. Within this range, the most favorable thickness for high areal variability depends on the season, especially whether ice growth or ice retreat processes dominate. Our findings suggest that thermodynamic melting (top, bottom, lateral) and growth (frazil, congelation) processes are more important than dynamical mechanisms, namely ice export and ridging, in controlling ice area variability.

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Supplementary material to "Future interannual variability of Arctic sea ice in coupled climate models"

10.5194/tc-2018-100-supplement ◽

2018 ◽

Author(s):

John R. Mioduszewski ◽

Steve Vavrus ◽

Muyin Wang ◽

Marika Holland ◽

Laura Landrum

Keyword(s):

Sea Ice ◽

Interannual Variability ◽

Climate Models ◽

Arctic Sea Ice ◽

Coupled Climate Models ◽

Arctic Sea ◽

Supplementary Material

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Network connectivity between the winter Arctic Oscillation and summer sea ice in CMIP6 models and observations

10.5194/tc-2021-387 ◽

2022 ◽

Author(s):

William Gregory ◽

Julienne Stroeve ◽

Michel Tsamados

Keyword(s):

Sea Ice ◽

Sea Level ◽

Arctic Oscillation ◽

Climate Models ◽

Sea Ice Concentration ◽

Sea Level Pressure ◽

The North ◽

Coupled Climate Models ◽

Ice Concentration ◽

Arctic Summer

Abstract. The indirect effect of winter Arctic Oscillation (AO) events on the proceeding summer Arctic sea ice extent suggests an inherent winter-to-summer mechanism for sea ice predictability. On the other hand, operational regional summer sea ice forecasts in a large number of coupled climate models show a considerable drop in predictive skill for forecasts initialised prior to the date of melt onset in spring, suggesting that some drivers of sea ice variability on longer time scales may not be well represented in these models. To this end, we introduce an unsupervised learning approach based on cluster analysis and complex networks to establish how well the latest generation of coupled climate models participating in phase 6 of the World Climate Research Programme Coupled Model Intercomparison Project (CMIP6) are able to reflect the spatio-temporal patterns of variability in northern-hemisphere winter sea-level pressure and Arctic summer sea ice concentration over the period 1979–2020, relative to ERA5 atmospheric reanalysis and satellite-derived sea ice observations respectively. Two specific global metrics are introduced as ways to compare patterns of variability between models and observations/reanalysis: the Adjusted Rand Index – a method for comparing spatial patterns of variability, and a network distance metric – a method for comparing the degree of connectivity between two geographic regions. We find that CMIP6 models generally reflect the spatial pattern of variability of the AO relatively well, although over-estimate the magnitude of sea-level pressure variability over the north-western Pacific Ocean, and under-estimate the variability over the north Africa and southern Europe. They also under-estimate the importance of regions such as the Beaufort, East Siberian and Laptev seas in explaining pan-Arctic summer sea ice area variability, which we hypothesise is due to regional biases in sea ice thickness. Finally, observations show that historically, winter AO events (negatively) covary strongly with summer sea ice concentration in the eastern Pacific sector of the Arctic, although now under a thinning ice regime, both the eastern and western Pacific sectors exhibit similar behaviour. CMIP6 models however do not show this transition on average, which may hinder their ability to make skilful seasonal to inter-annual predictions of summer sea ice.

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Sensitivity of Antarctic sea ice to the Southern Annular Mode in coupled climate models

Climate Dynamics ◽

10.1007/s00382-016-3424-9 ◽

2016 ◽

Vol 49 (5-6) ◽

pp. 1813-1831 ◽

Cited By ~ 30

Author(s):

Marika M. Holland ◽

Laura Landrum ◽

Yavor Kostov ◽

John Marshall

Keyword(s):

Sea Ice ◽

Climate Models ◽

Southern Annular Mode ◽

Annular Mode ◽

Antarctic Sea Ice ◽

Coupled Climate Models

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Future interannual variability of Arctic sea ice in coupled climate models

10.5194/tc-2018-100 ◽

2018 ◽

Author(s):

John R. Mioduszewski ◽

Steve Vavrus ◽

Muyin Wang ◽

Marika Holland ◽

Laura Landrum

Keyword(s):

Sea Ice ◽

Climate Models ◽

Coupled Model ◽

Arctic Sea Ice ◽

Cmip5 Models ◽

Coupled Climate Models ◽

Arctic Sea ◽

Ice Retreat ◽

Intercomparison Project ◽

Ice Pack

Abstract. The diminishing Arctic sea ice pack has been widely studied, but mostly focused on time-mean changes in sea ice rather than on short-term variations that also have important physical and societal consequences. In this study we test the hypothesis that future interannual Arctic sea ice area variability will increase by utilizing a set of 40 independent simulations from the Community Earth System Model's Large Ensemble (CESM-LE) for the 1920–2100 period, and augment this with simulations from 12 models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Both CESM-LE and CMIP5 models project that ice area variability will indeed grow substantially, but not monotonically, in all months, and with a strong seasonal dependence in magnitude and timing that is robust among CESM ensemble members. The variability in every month is inversely correlated with the average ice retreat rate before there is an eventual disappearance in both terms as the ice pack becomes seasonal in summer and autumn by late century. The peak in variability correlates best with the total area of ice between 0.2 m and 0.6 m monthly thickness, indicating that substantial future thinning of the ice pack is required before variability maximizes. Within this range, the most favorable thickness for high areal variability depends on the season, primarily due to whether ice growth or ice retreat processes dominate. Thermodynamic processes are found to be more important than dynamical mechanisms, namely ice export and ridging, in controlling ice area variability.

Download Full-text