Surface Salinity Under Transitioning Ice Cover in the Canada Basin: Climate Model Biases Linked to Vertical Distribution of Fresh Water

Rosenblum, Erica; Fajber, Robert; Stroeve, Julienne; Gille, Sarah T.; Tremblay, L. Bruno; Carmack, Eddy C.

doi:10.1029/2021gl094739

Cited by 16 publications

(17 citation statements)

References 57 publications

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“…The lower multidecadal variability is associated with the buoyancy forcing (W. M. Kim et al., 2017), and is also partially related to the wind forcing (Yan et al., 2018; J. Zhao & Johns, 2014). Recent reconstructions of the long‐term mean AMOC structure suggests that the Arctic is the northern terminus of the mean AMOC (Zhang & Thomas, 2021), and the simulated lower multidecadal AMOC variability is likely related to the underestimated multidecadal Arctic salinity variations in climate models due to the model biases in the Arctic (Rosenblum et al., 2021). Nevertheless, detailed discussion on the underlying reasons for the muted multidecadal AMOC variability is beyond the scope of this study.…”

Section: Model Simulations and Resultsmentioning

confidence: 99%

Performance of Two‐Moment Stratiform Microphysics With Prognostic Precipitation in GFDL's CM4.0

Guo

Ming

Fan

et al. 2022

J Adv Model Earth Syst

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We describe the model performance of a new global coupled climate model configuration, CM4‐MG2. Beginning with the Geophysical Fluid Dynamics Laboratory's fourth‐generation physical climate model (CM4.0), we incorporate a two‐moment Morrison‐Gettelman bulk stratiform microphysics scheme with prognostic precipitation (MG2), and a mineral dust and temperature‐dependent cloud ice nucleation scheme. We then conduct and analyze a set of fully coupled atmosphere‐ocean‐land‐sea ice simulations, following Coupled Model Intercomparison Project Phase 6 protocols. CM4‐MG2 generally captures CM4.0's baseline simulation characteristics, but with several improvements, including better marine stratocumulus clouds off the west coasts of Africa and North and South America, a reduced bias toward “double” Intertropical Convergence Zones south of the equator, and a stronger Madden‐Julian Oscillation (MJO). Some degraded features are also identified, including excessive Arctic sea ice extent and a stronger‐than‐observed El Nitruen∼ $\tilde{\mathrm{n}}$o‐Southern Oscillation. Compared to CM4.0, the climate sensitivity is reduced by about 10% in CM4‐MG2.

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Section: Model Simulations and Resultsmentioning

confidence: 99%

Performance of Two‐Moment Stratiform Microphysics With Prognostic Precipitation in GFDL's CM4.0

Guo

Ming

Fan

et al. 2022

J Adv Model Earth Syst

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“…Climate models often underestimate the amplitude of multidecadal AMOC variability (e.g., Kim et al., 2018; Yan et al., 2018), which might be related to the underestimated Arctic salinity anomalies in climate models (Rosenblum et al., 2021). Recent observations show significant negative salinity anomalies in the Arctic (e.g., Rosenblum et al., 2021; J. Zhang et al., 2021).…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Section: Conclusion and Discussionmentioning

confidence: 99%

A Simple Conceptual Model for the Self‐Sustained Multidecadal AMOC Variability

Wei

Zhang

2022

Geophysical Research Letters

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Multidecadal variability of Atlantic Meridional Overturning Circulation (AMOC) has been reconstructed by various proxies, simulated in climate models, and linked to multidecadal Arctic salinity variability. Here we construct a simple conceptual model to understand the two‐way interactions of the Arctic with multidecadal AMOC variability through a delayed oscillator mechanism. We revise Stommel's Two‐Box Model by including an advective time delay for the Arctic density/salinity anomalies to reach the subpolar North Atlantic and a coupled negative feedback between the AMOC and the freshwater flux entering the Arctic through atmosphere and/or sea ice responses. Self‐sustained multidecadal AMOC oscillations exist in the revised Stommel's Two‐Box model if the oceanic advective time delay is longer than the oscillation threshold, and the periods of the AMOC delayed oscillator depend crucially on this advective time delay. The coupled freshwater feedback provides additional delayed negative feedback and reduces the advective time delay threshold required for the oscillations.

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“…Yet the loss of Arctic Ocean stratification, which is required to prevent winter sea ice formation, may impart hysteresis to subsequent winter sea ice reformation, a possibility that climate modeling studies have not yet investigated in sufficient detail. Indeed, global ice‐ocean models and state‐of‐the‐art coupled climate models struggle to accurately simulate an upper‐ocean stratification that is as stable as observed (G. Holloway et al., 2007; Ilıcak et al., 2016; Rosenblum et al., 2021).…”

Section: Regional Candidate Tipping Elementsmentioning

confidence: 99%

Mechanisms and Impacts of Earth System Tipping Elements

Wang

Foster

Lenz

et al. 2023

Reviews of Geophysics

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Tipping elements are components of the Earth system which may respond nonlinearly to anthropogenic climate change by transitioning toward substantially different long-term states upon passing key thresholds or "tipping points." In some cases, such changes could produce additional greenhouse gas emissions or radiative forcing that could compound global warming. Improved understanding of tipping elements is important for predicting future climate risks and their impacts. Here we review mechanisms, predictions, impacts, and knowledge gaps associated with 10 notable Earth system components proposed to be tipping elements. We evaluate which tipping elements are approaching critical thresholds and whether shifts may manifest rapidly or over longer timescales. Some tipping elements have a higher risk of crossing tipping points under middle-of-the-road emissions pathways and will possibly affect major ecosystems, climate patterns, and/or carbon cycling within the 21st century. However, literature assessing different emissions scenarios indicates a strong potential to reduce impacts associated with many tipping elements through climate change mitigation. The studies synthesized in our review suggest most tipping elements do not possess the potential for abrupt future change within years, and some proposed tipping elements may not exhibit tipping behavior, rather responding more predictably and directly to the magnitude of forcing. Nevertheless, uncertainties remain associated with many tipping elements, highlighting an acute need for further research and modeling to better constrain risks. Plain Language SummaryIn recent years, discussions of climate change have shown growing interest in "tipping elements" of the Earth system, also imprecisely referred to as "tipping points." This refers to Earth system components like the tropical rainforests of Amazonia or the Greenland and Antarctic ice sheets which may exhibit large-scale, long-term changes upon reaching critical global warming, greenhouse gas, or other thresholds. Once such thresholds are passed, some tipping elements could in turn produce additional greenhouse gas emissions or change the Earth's energy balance in ways that moderately reinforce warming. In this review, we summarize the current state of scientific knowledge on 10 systems that some have referred to as potential tipping elements of the climate system. We describe the mechanisms important to each system, highlight the response of these systems to climate change so far, and explain the dynamics of potential future changes that these systems could undergo in response to further climate change. Overall, even considering remaining scientific uncertainties, tipping elements will influence future climate change and may involve major impacts on ecosystems, climate patterns, and the carbon cycle starting later this century. Aggressive efforts to stabilize climate change could significantly reduce such impacts.

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Surface Salinity Under Transitioning Ice Cover in the Canada Basin: Climate Model Biases Linked to Vertical Distribution of Fresh Water

Abstract: Rapid sea ice retreat has been extensively observed in the Canada Basin over the past several decades (F. McLaughlin et al., 2011). The increased sea ice melt and river runoff that has collected toward the center of the anticyclonic (convergent)

Cited by 16 publications

References 57 publications

Performance of Two‐Moment Stratiform Microphysics With Prognostic Precipitation in GFDL's CM4.0

Performance of Two‐Moment Stratiform Microphysics With Prognostic Precipitation in GFDL's CM4.0

A Simple Conceptual Model for the Self‐Sustained Multidecadal AMOC Variability

Mechanisms and Impacts of Earth System Tipping Elements

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