AMOC Recovery in a Multicentennial Scenario Using a Coupled Atmosphere‐Ocean‐Ice Sheet Model

Ackermann, Lars; Danek, Christopher; Gierz, Paul; Lohmann, Gerrit

doi:10.1029/2019gl086810

Cited by 25 publications

(13 citation statements)

References 66 publications

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“…The rate of ice sheet mass loss (and hence freshwater input to the ocean) is likely to become even larger in the future and thus exceed the maximum rates of the past 12,000 years (Briner et al., 2020). Incorporating the relevant cryosphere processes into climate models will be necessary for improving simulation results and providing more faithful freshwater‐related projections in the future (e.g., Ackermann et al., 2020; Muntjewerf et al., 2020).…”

Section: Discussionmentioning

confidence: 99%

Arctic Ocean Freshwater in CMIP6 Coupled Models

Wang

et al. 2022

Earth's Future

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In this study we assessed the representation of the sea surface salinity (SSS) and liquid freshwater content (LFWC) of the Arctic Ocean in the historical simulation of 31 CMIP6 models with comparison to 39 Coupled Model Intercomparison Project phase 5 (CMIP5) models, and investigated the projected changes in Arctic liquid and solid freshwater content and freshwater budget in scenarios with two different shared socioeconomic pathways (SSP2‐4.5 and SSP5‐8.5). No significant improvement was found in the SSS and LFWC simulation from CMIP5 to CMIP6, given the large model spreads in both CMIP phases. The overestimation of LFWC continues to be a common bias in CMIP6. In the historical simulation, the multi‐model mean river runoff, net precipitation, Bering Strait and Barents Sea Opening (BSO) freshwater transports are 2,928 ± 1,068, 1,839 ± 3,424, 2,538 ± 1,009, and −636 ± 553 km3/year, respectively. In the last decade of the 21st century, CMIP6 MMM projects these budget terms to rise to 4,346 ± 1,484 km3/year (3,678 ± 1,255 km3/year), 3,866 ± 2,935 km3/year (3,145 ± 2,651 km3/year), 2,631 ± 1,119 km3/year (2,649 ± 1,141 km3/year) and 1,033 ± 1,496 km3/year (449 ± 1,222 km3/year) under SSP5‐8.5 (SSP2‐4.5). Arctic sea ice is expected to continue declining in the future, and sea ice meltwater flux is likely to decrease to about zero in the mid‐21st century under both SSP2‐4.5 and SSP5‐8.5 scenarios. Liquid freshwater exiting Fram and Davis straits will be higher in the future, and the Fram Strait export will remain larger. The Arctic Ocean is projected to hold a total of 160,300 ± 62,330 km3 (141,590 ± 50,310 km3) liquid freshwater under SSP5‐8.5 (SSP2‐4.5) by 2100, about 60% (40%) more than its historical climatology.

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Section: Discussionmentioning

confidence: 99%

Arctic Ocean Freshwater in CMIP6 Coupled Models

Wang

et al. 2022

Earth's Future

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“…Some more recent earth system models demonstrate similar behaviour with the inclusion of dynamic ice sheet models (e.g. see Lofverstrom and Liakka 2018;Lofverstrom et al 2020;Ackermann et al 2020;Gregory et al 2020), and some groups have developed dynamiccontinent components within this framework (Meccia and Mikolajewicz 2018). However, ice sheets and their associated geographical features are still mostly externally prescribed in palaeoclimate simulations.…”

Section: Introductionmentioning

confidence: 89%

Effect of orographic gravity wave drag on Northern Hemisphere climate in transient simulations of the last deglaciation

et al. 2022

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Long transient simulations of the last deglaciation are increasingly being performed to identify the drivers of multiple rapid Earth system changes that occurred in this period. Such simulations frequently prescribe temporal variations in ice sheet properties, which can play an important role in controlling atmospheric and surface climate. To preserve a model’s standard performance in simulating climate, it is common to apply time dependent orographic variations, including parameterised sub-grid scale orographic variances, as anomalies from the pre-industrial state. This study investigates the causes of two abrupt climate change events in the Northern Hemisphere extratropics occurring between 16 and 14 thousand years ago in transient simulations of the last deglaciation from the Hadley Centre coupled general circulation model (HadCM3). One event is characterized by regional Northern Hemisphere changes comprising a centennial scale cooling of ~ 10 °C across Fennoscandia followed by rapid warming in less than 50 years as well as synchronous shifts in the Northern Annular Mode. The second event has comparable but temporally reversed characteristics. Sensitivity experiments reveal the climate anomalies are exclusively caused by artificially large values of orographic gravity wave drag, resulting from the combined use of the orographic anomaly method along with a unique inclusion of transient orography that linearly interpolates between timesteps in the ice sheet reconstruction. Palaeoclimate modelling groups should therefore carefully check the effects of their sub-grid scale orographic terms in transient palaeoclimate simulations with prescribed topographic evolution.

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“…The Langevin equation has been posited before as being suitable to capture the essential dynamics of an AMOC collapse (Ditlevsen and Johnsen, 2010;Berglund and Gentz, 2002). It has also been used elsewhere as the basis for describing the dynamics of climate subsystems (Kwasniok and Lohmann, 2009;Livina et al, 2010) and the AMOC in particular (Kleinen et al, 2003;Held and Kleinen, 2004).…”

Section: Introductionmentioning

confidence: 99%

“…It has also been used elsewhere as the basis for describing the dynamics of climate subsystems (Kwasniok and Lohmann, 2009;Livina et al, 2010) and the AMOC in particular (Kleinen et al, 2003;Held and Kleinen, 2004). A fourthorder potential function is used in Ditlevsen and Johnsen (2010); Berglund and Gentz (2002) because it is the minimum required for having three distinct solutions (double wells). This potential function has two parameters, which are presumed to be functions of the freshwater forcing.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of Atlantic meridional overturning hysteresis using Langevin dynamics

2021

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Abstract. Hysteresis diagrams of the Atlantic meridional overturning circulation (AMOC) under freshwater forcing from climate models of intermediate complexity are fitted to a simple model based on the Langevin equation. A total of six parameters are sufficient to quantitatively describe the collapses seen in these simulations. Reversing the freshwater forcing results in asymmetric behaviour that is less well captured and appears to require a more complicated model. The Langevin model allows for comparison between models that display an AMOC collapse. Differences between the climate models studied here are mainly due to the strength of the stable AMOC and the strength of the response to a freshwater forcing.

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AMOC Recovery in a Multicentennial Scenario Using a Coupled Atmosphere‐Ocean‐Ice Sheet Model

Cited by 25 publications

References 66 publications

Arctic Ocean Freshwater in CMIP6 Coupled Models

Arctic Ocean Freshwater in CMIP6 Coupled Models

Effect of orographic gravity wave drag on Northern Hemisphere climate in transient simulations of the last deglaciation

Characterisation of Atlantic meridional overturning hysteresis using Langevin dynamics

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