Understanding AMOC stability: the North Atlantic Hosing Model Intercomparison Project

Geoscientific model development, Journal Year: 2023, Volume and Issue: 16(7), P. 1975 - 1995

Published: April 6, 2023

Abstract. The Atlantic meridional overturning circulation (AMOC) is an important part of our climate system. AMOC predicted to weaken under change; however, theories suggest that it may have a tipping point beyond which recovery difficult, hence showing quasi-irreversibility (hysteresis). Although hysteresis has been seen in simple models, difficult demonstrate comprehensive global models. Here, we outline set experiments designed explore and sensitivity additional freshwater input as the North Hosing Model Intercomparison Project (NAHosMIP). These include adding (hosing) for fixed length time examine rate mechanisms weakening whether subsequently recovers once hosing stops. Initial results are shown from eight models participating Sixth Coupled (CMIP6). weakens all result freshening, but freshening ceases, half other stays weakened state. difference model behaviour cannot be explained by ocean resolution or type nor details subgrid-scale parameterisations. Likewise, previously proposed properties mean state such strength salinity advection feedback. Instead, determined reached when stops, with those where weakest not experiencing recovery.

Language: Английский

---

Remotely sensing potential climate change tipping points across scales

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: Jan. 6, 2024

Potential climate tipping points pose a growing risk for societies, and policy is calling improved anticipation of them. Satellite remote sensing can play unique role in identifying anticipating phenomena across scales. Where satellite records are too short temporal early warning points, complementary spatial indicators leverage the exceptional spatial-temporal coverage remotely sensed data to detect changing resilience vulnerable systems. Combining Earth observation with system models improve process-based understanding their interactions, potential cascades. Such fine-resolution support point management

Language: Английский

---

Climate tipping point interactions and cascades: a review

Earth System Dynamics, Journal Year: 2024, Volume and Issue: 15(1), P. 41 - 74

Published: Jan. 26, 2024

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 (AMOC), 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 paleoclimate reconstructions where multi-component spatially propagating transitions were potentially at play. uncertainties large, find indications many destabilizing. Therefore, conclude should not only be in isolation, but also more emphasis has put interactions. This means cascades cannot ruled centennial millennial timescales warming levels 1.5 2.0 ∘C shorter if surpassed ∘C. At these higher then fast AMOC address crucial gaps element interactions, propose four strategies combining observation-based approaches, system modeling expertise, computational advances, expert knowledge.

Language: Английский

---

Ubiquitous acceleration in Greenland Ice Sheet calving from 1985 to 2022

Nature, Journal Year: 2024, Volume and Issue: 625(7995), P. 523 - 528

Published: Jan. 17, 2024

Language: Английский

---

Impacts of a weakened AMOC on precipitation over the Euro-Atlantic region in the EC-Earth3 climate model

Climate Dynamics, Journal Year: 2023, Volume and Issue: 61(7-8), P. 3397 - 3416

Published: March 16, 2023

Abstract Given paleoclimatic evidence that the Atlantic Meridional Overturning Circulation (AMOC) may affect global climate system, we conduct model experiments with EC-Earth3, a state-of-the-art GCM, to specifically investigate, for first time, mechanisms of precipitation change over Euro-Atlantic sector induced by weakened AMOC. We artificially weaken strength AMOC in through release freshwater anomaly into Northern Hemisphere high latitude ocean, thereby obtaining ~ 57% weaker respect its preindustrial 60 years. Similar prior studies, find decreases response However, also frequency wet days increases some regions. By computing atmospheric moisture budget, intensified but drier storms cause less land. Nevertheless, changes jet stream tend enhance northwestern Europe. further investigate association anomalies large-scale circulations weather regimes clustering geopotential height daily anomalies. an increase positive phase North Oscillation (NAO+), which is associated occurrence northern Europe and conditions southern Since reduction within inter-model range projected declines end twenty-first century, our results have implications understanding role future hydrological changes.

Language: Английский

---

Understanding AMOC stability: the North Atlantic Hosing Model Intercomparison Project

Published: Nov. 25, 2022

Abstract. The Atlantic meridional overturning circulation (AMOC) is an important part of our climate system. AMOC predicted to weaken under change, however there are theories that it may have a tipping point beyond which recovery difficult, hence showing quasi-irreversibility (hysteresis). Although hysteresis has been seen in simple models, difficult demonstrate comprehensive global models. Here we outline set experiments designed explore and sensitivity additional freshwater input as the North hosing model intercomparison project (NAHosMIP). These include adding (hosing) for fixed length time examine rate mechanisms or weakening, whether subsequently recovers once stops. Initial results shown from eight models participating Sixth Coupled Model Intercomparison Project (CMIP6). weakens all freshening, but freshening ceases, half other stays weakened state. difference behaviour cannot be explained by ocean resolution type, details subgridscale parameterizations. Nor can previously proposed properties mean state such strength salinity advection feedback. Instead determined reached when stops, with those where weakest not experiencing recovery.

Language: Английский

---

On the ocean's response to enhanced Greenland runoff in model experiments: relevance of mesoscale dynamics and atmospheric coupling

Ocean science, Journal Year: 2023, Volume and Issue: 19(1), P. 141 - 167

Published: Feb. 20, 2023

Abstract. Increasing Greenland Ice Sheet melting is anticipated to impact water mass transformation in the subpolar North Atlantic and ultimately meridional overturning circulation. Complex ocean climate models are widely applied estimate magnitude timing of related impacts under global warming. We discuss role mean state, transformation, mesoscale eddies, atmospheric coupling shaping response Ocean enhanced runoff. In a suite eight dedicated 60- 100-year-long model experiments with without coupling, eddy processes parameterized explicitly simulated regular significantly enlarged runoff, we find (1) major by interactive atmosphere enabling compensating temperature feedback, (2) non-negligible influence state biased towards greater stability coupled simulations, both which make circulation less susceptible freshwater perturbation applied, (3) more even spreading deeper mixing runoff tracer inter-gyre exchange subtropics strongly eddying simulations. Overall, our demonstrate important dynamics feedback projections system hence underline necessity advance scale-aware parameterizations for next-generation models.

Language: Английский

---

Climate tipping point interactions and cascades: A review

Published: Aug. 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.

Language: Английский

---

Role of multi-decadal variability of the winter North Atlantic Oscillation on Northern Hemisphere climate

Environmental Research Letters, Journal Year: 2023, Volume and Issue: 18(4), P. 044046 - 044046

Published: March 15, 2023

Abstract The North Atlantic Oscillation (NAO) plays a leading role in modulating wintertime climate over the and surrounding continents of Europe America. Here we show that observed evolution NAO displays larger multi-decadal variability than simulated by nearly all CMIP6 models. To investigate as pacemaker variability, analyse simulations are constrained to follow NAO. We use particle filter data-assimilation technique sub-selects members among an ensemble simulations, well El Niño Southern Annular Mode global model, without nudging terms. Since model also contains external forcings, these can be used compare forced response effect three assimilated modes. Concentrating on 28 year periods strongest trends, leads large trends temperature precipitation Northern Hemisphere land sea-ice concentration. subpolar gyre region is particularly strongly influenced NAO, with links found both concurrent atmospheric Meridional Overturning Circulation (AMOC). Care thus needs taken account for impacts when using sea surface this proxy AMOC strength decadal time-scales. Our results have important implications analyses highlight need further work understand causes variability.

Language: Английский

---

Can we trust projections of AMOC weakening based on climate models that cannot reproduce the past?

Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences, Journal Year: 2023, Volume and Issue: 381(2262)

Published: Oct. 22, 2023

The Atlantic Meridional Overturning Circulation (AMOC), a crucial element of the Earth's climate system, is projected to weaken over course twenty-first century which could have far reaching consequences for occurrence extreme weather events, regional sea level rise, monsoon regions and marine ecosystem. latest IPCC report puts likelihood such weakening as 'very likely'. As our confidence in future projections depends largely on ability model past climate, we take an in-depth look at difference twentieth evolution AMOC based observational data (including direct observations various proxy data) from ensembles. We show that both magnitude trend different time periods often even sign differs between ensemble mean, with becoming greater when looking CMIP6 compared CMIP5. discuss possible reasons this observation-model discrepancy question what it means higher than historical reproductions. This article part discussion meeting issue 'Atlantic overturning: new challenges'.

Language: Английский

---