Simulating AMOC tipping driven by internal climate variability with a rare event algorithm

npj Climate and Atmospheric Science, Год журнала: 2024, Номер 7(1)

Опубликована: Янв. 29, 2024

Abstract This study investigates the possibility of Atlantic Meridional Overturning Circulation (AMOC) noise-induced tipping solely driven by internal climate variability without applying external forcing that alter radiative or North freshwater budget. We address this hypothesis a rare event algorithm to ensemble simulations present-day with an intermediate complexity model. The successfully identifies trajectories leading abrupt AMOC slowdowns, which are unprecedented in 2000-year control run. Part these weakened states lead collapsed state evidence recovery on multi-centennial time scales. temperature and Northern Hemisphere jet stream responses internally-induced slowdowns show strong similarities those found externally forced state-of-the-art models. slowdown seems be initially Ekman transport due westerly wind stress anomalies subsequently sustained complete collapse oceanic convection Labrador Sea. These results demonstrate transitions purely model simulation but theoretically possible. Additionally, algorithms tool valuable general interest points since they introduce collecting large number events cannot sampled using traditional approaches. opens identifying mechanisms driving complex systems little a-priori knowledge is available.

Язык: Английский

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Climate tipping point interactions and cascades: A review

Опубликована: Авг. 1, 2023

Abstract. Climate tipping elements are large-scale subsystems of the Earth that may transgress critical thresholds (tipping points) under ongoing global warming, with substantial impacts on biosphere and human societies. Frequently studied examples such include Greenland Ice Sheet, Atlantic Meridional Overturning Circulation, permafrost, monsoon systems, Amazon rainforest. While recent scientific efforts have improved our knowledge about individual elements, interactions between them less well understood. Also, potential events to induce additional elsewhere, or stabilize other is largely unknown. Here, we map out current state literature climate review influences them. To do so, gathered evidence from model simulations, observations conceptual understanding, as archetypal paleoclimate reconstructions where multi-component spatially propagating transitions were potentially at play. Lastly, identify crucial gaps in element outline how future research could address those gaps.

Язык: Английский

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Impacts and State‐Dependence of AMOC Weakening in a Warming Climate

Geophysical Research Letters, Год журнала: 2024, Номер 51(10)

Опубликована: Май 13, 2024

Abstract All climate models project a weakening of the Atlantic Meridional Overturning Circulation (AMOC) strength in response to greenhouse gas forcing. However, impacts AMOC decline alone cannot be isolated from other drivers change using existing Coupled Model Intercomparison Project simulations. To address this issue, we conduct idealized experiments EC‐Earth3 model. We compare an abrupt 4×CO 2 simulation with same experiment, except artificially fix at preindustrial levels. With design, can formally attribute differences between these two decline. In addition, quantify state‐dependence by comparing aforementioned which reduce strength. Our findings demonstrate that are state‐dependent, thus understanding on future requires targeted model experiments.

Язык: Английский

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Opportunities for Earth Observation to Inform Risk Management for Ocean Tipping Points

Surveys in Geophysics, Год журнала: 2024, Номер 46(2), С. 443 - 502

Опубликована: Ноя. 6, 2024

Abstract As climate change continues, the likelihood of passing critical thresholds or tipping points increases. Hence, there is a need to advance science for detecting such thresholds. In this paper, we assess needs and opportunities Earth Observation (EO, here understood refer satellite observations) inform society in responding risks associated with ten potential large-scale ocean elements: Atlantic Meridional Overturning Circulation; Subpolar Gyre; Beaufort Arctic halocline; Kuroshio Large Meander; deoxygenation; phytoplankton; zooplankton; higher level ecosystems (including fisheries); marine biodiversity. We review current scientific understanding identify specific EO related modelling each these elements. draw out some generic that apply across several These common include importance maintaining long-term, consistent time series; combine data consistently situ types subsurface), example through assimilation; reduce work mismatches resolution (in both directions) between models datasets. Our analysis shows developing EO, prediction systems together, strengths limitations each, provides many promising paths towards monitoring early warning tipping, development next generation models.

Язык: Английский

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Persistently Elevated High‐Latitude Ocean Temperatures and Global Sea Level Following Temporary Temperature Overshoots

Earth s Future, Год журнала: 2024, Номер 12(10)

Опубликована: Окт. 1, 2024

Abstract As exceeding the 1.5°C level of global warming is likely to happen in near future, understanding response ocean‐climate system temporarily overshooting this critical importance. Here, we apply Adaptive Emissions Reduction Approach Earth System Model GFDL‐ESM2M conduct novel overshoot scenarios that reach 2.0, 2.5 and 3.0°C before returning over time period 1861–2500. We also perform a complementary scenario stabilizes temperature at 1.5°C, allowing isolate impacts caused by overshoots alone, both during their peaks after reversals. The simulations indicate substantial residual ocean surface persists high latitudes overshoots, with most notable regional anomalies occurring North Atlantic (up +3.1°C 3°C compared stabilization scenario) Southern Ocean (+1.2°C). primarily driven recoveries meridional overturning circulation associated increases heat transport. Excess subsurface storage low mid‐latitudes prevents steric sea rise (SLR) from reverting levels any scenario, remaining up 32% higher on centennial scales. Both peak persistent changes reversal bear significant implications for future assessments coastlines, climates, marine ecosystems, ice sheets.

Язык: Английский

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Contrasting internally and externally generated Atlantic Multidecadal Variability and the role for AMOC in CMIP6 historical simulations

Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences, Год журнала: 2023, Номер 381(2262)

Опубликована: Окт. 22, 2023

Atlantic multidecadal variability (AMV) has long been thought to be an expression of low-frequency in the Meridional Overturning Circulation (AMOC). However, alternative hypotheses have forwarded, including that AMV is primarily externally forced. Here, we review current state play by assessing historical simulations made for sixth coupled model intercomparison project (CMIP6). Overall, importance external forcing sensitive type index used, due globally coherent forced signals models. There are also significant contrasts between processes drive internally and AMV, but these can isolated exploring multivariate AMV. Specifically, internal CMIP6 models consistent with important role ocean circulation AMOC largely a surface-flux mechanism little ocean. fingerprint similar observed, appears inconsistent observations. Therefore, climate still suggest key dynamics, specifically AMOC, observed Nevertheless, remain deficient number areas, stronger dynamical changes cannot ruled out. This article part discussion meeting issue 'Atlantic overturning: new observations challenges'.

Язык: Английский

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A novel conceptual model for Dansgaard–Oeschger event dynamics based on ice-core data

Climate of the past, Год журнала: 2025, Номер 21(1), С. 115 - 132

Опубликована: Янв. 16, 2025

Abstract. This study introduces a novel dynamical systems model designed to capture the highly non-periodic nature of Dansgaard–Oeschger (DO) events. Such events are difficult adequately due their variable durations (some lasting around 1 century, while others span multiple millennia) and occurrence short precursor that precede longer DO despite similar boundary climate conditions. Utilising simplified two-equation framework derived from Stommel model, our approach integrates an internal control parameter which acts as feedback on Antarctic Bottom Water (AABW) formation. Through both analytical numerical methods, we establish suitable domain within newly adjusted models can accurately replicate palaeoclimatic records described by summary statistics ice-core data. The analysis also shows that, without parameter, does not have in it reproduce wide range event characteristics seen record. provides new insights into underlying mechanisms driving these significant phenomena necessary timescale they forced allowing model's parameters vary through time. allows achieve unprecedented precision capturing realistic sequence with timing matching those observational refined only enhances understanding cycles but demonstrates potential simple simulate complex interactions.

Язык: Английский

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Comparing the impacts of vertical mixing enhancement on AMOC at the eastern and western boundaries of Atlantic

Climate Dynamics, Год журнала: 2025, Номер 63(2)

Опубликована: Фев. 1, 2025

Язык: Английский

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Noise-shaped hysteresis cycles of the AMOC under increasing CO2 forcing

Chaos An Interdisciplinary Journal of Nonlinear Science, Год журнала: 2025, Номер 35(2)

Опубликована: Фев. 1, 2025

The Atlantic Meridional Overturning Circulation (AMOC) stability landscape is commonly investigated with single-realization hysteresis diagrams driven by freshwater input in the North Ocean. However, effect of CO2 forcing on one side and role internal climate variability timing tipping AMOC other remain less explored. Here, we address this gap running three independent simulations, consisting a slow ramp-up plus ramp-down concentration (0.2 ppm/year) within PlaSim-Large-Scale Geostrophic (LSG) intermediate complexity model. We show that realizations CO2-driven cycle, particularly, recovery, are remarkably affected variability. In even observe reversed where recovers at higher level than collapse point. While statistical Early Warning Signals (EWSs) some success detecting points, also find EWS considerably reduces predictability leads to false positives an approaching tipping. suggest presence may have characteristics deviate substantially from behavior seen simple models caution needed when interpreting results single-experiment realization. Our findings highlight need for probabilistic approach defining “safe operating space” stability, since it might not be possible define single critical threshold prevent collapse.

Язык: Английский

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Extreme cold events in Europe under a reduced AMOC

Environmental Research Letters, Год журнала: 2023, Номер 19(1), С. 014054 - 014054

Опубликована: Дек. 12, 2023

Abstract There is a consensus that weakened Atlantic Meridional Overturning Circulation (AMOC) decreases mean surface temperature in the Northern Hemisphere, both over ocean and continents. However, impacts of reduced AMOC on cold extreme events have not yet been examined. We analyse strength Europe using targeted sensitivity experiments with EC-Earth3 climate model. Starting from fully coupled ocean-atmosphere simulation which was artificially reduced, set atmosphere-only integrations prescribed sea sea-ice cover conducted to evaluate effects weakly strongly strength. Despite overall cooling, leads fewer winter spells Europe. find intensifies near-surface meridional gradient North Europe, thus providing energy boost jet stream. A stronger stream less atmospheric blocking, reducing frequency Although limited output one model, our results indicate may play role shaping future change by modulating blocking.

Язык: Английский

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