Multiple Equilibria of the Global Thermohaline Circulation

Marotzke, Jochem; Willebrand, Jürgen

doi:10.1175/1520-0485(1991)021<1372:meotgt>2.0.co;2

Cited by 246 publications

(167 citation statements)

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“…The possibility for an AMOC switching between an AMOC on state and AMOC off state (a collapsed or weak AMOC) has been a subject of modelling studies for many years, beginning with simple box model studies (Stommel, 1961;Marotzke, 1990;Rahmstorf, 1996) and continuing up to complex climate model studies (Manabe and Stouffer, 1988;Stouffer et al, 2006;Mecking et al, 2016). The freshwater transport by the AMOC has been proposed as an indicator of AMOC bi-stability (Rahmstorf, 1996;de Vries and Weber, 2005) and is referred to as M ov (F ov in some studies).…”

Section: Introductionmentioning

confidence: 99%

The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability

Mecking¹,

Drijfhout²,

Jackson³

et al. 2017

Tellus A: Dynamic Meteorology and Oceanography

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Evidence from paleo-proxy records suggests that the Atlantic Meridional Overturning Circulation (AMOC) can be in both an AMOC on state, the AMOC as we observe it today, and an AMOC off state, where the AMOC becomes extremely weak or even collapses. The freshwater transport due to the AMOC (M ov ) at 34°S in the Atlantic has often been used as an indicator for bi-stability, with a positive M ov suggesting a monostable AMOC and a negative M ov suggesting a bi-stable AMOC. Often studies have shown that the sign of the divergence of the M ov might be a good indicator of AMOC bi-stability. In this study we investigate how model bias affects the sign of M ov across all latitudes in the Atlantic basin, through a detailed analysis of the Coupled Model Inter-Comparison Project 5 (CMIP5) model ensemble. M ov , in the CMIP5 models is generally too positive in the southern Atlantic due to a salinity bias, while in the subtropical North Atlantic the values of M ov are influenced by a combination of velocity and salinity biases. We compare these results to observations, reanalysis products and Hadley Centre Global Environmental Model version 3 global configuration version 2, a current generation coupled model which exhibits a stable AMOC off state, and discuss the differences that can lead to the possibility of a bi-stable AMOC as opposed to a monostable AMOC.

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Section: Introductionmentioning

confidence: 99%

The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability

Mecking¹,

Drijfhout²,

Jackson³

et al. 2017

Tellus A: Dynamic Meteorology and Oceanography

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“…Model studies have shown that in the Nordic Seas changes in the freshwater flux (including sea ice) may inhibit convection and in turn have major impact on the patterns and strength of the thermohaline circulation (e.g. Broecker et al, 1990;Marotzke and Willebrand, 1991).…”

Section: Introductionmentioning

confidence: 99%

Inter-ocean fluxes south of Africa in an eddy-permitting model

Reason

Lütjeharms

Hermes

et al. 2003

Deep Sea Research Part II: Topical Studies in Oceanography

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“…Marotzke and Willebrand, 1991;Power and Kleeman, 1993;Mikolajewicz and Maier-Reimer, 1994;Bigg et al, 1998). More recent coupled model results (Rahmstorf, 1995;Ganopolski and Rahmstorf, 2001;Rind et al, 2001a,b) have suggested that there are bifurcation points in the dependence of THC overturning strength on freshwater forcing, so that the THC could exist in more than one stable, or quasi-stable, state.…”

Section: Thermohaline Catastrophesmentioning

confidence: 99%

The role of the oceans in climate

Bigg

Jickells

Liss

et al. 2003

Intl Journal of Climatology

124

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The ocean is increasingly seen as a vital component of the climate system. It exchanges with the atmosphere large quantities of heat, water, gases, particles and momentum. It is an important part of the global redistribution of heat from tropics to polar regions keeping our planet habitable, particularly equatorward of about 30°. In this article we review recent work examining the role of the oceans in climate, focusing on research in the Third Assessment Report of the IPCC and later. We discuss the general nature of oceanic climate variability and the large role played by stochastic variability in the interaction of the atmosphere and ocean. We consider the growing evidence for biogeochemical interaction of climatic significance between ocean and atmosphere. Air-sea exchange of several radiatively important gases, in particular CO 2 , is a major mechanism for altering their atmospheric concentrations. Some more reactive gases, such as dimethyl sulphide, can alter cloud formation and hence albedo. Particulates containing iron and originating over land can alter ocean primary productivity and hence feedbacks to other biogeochemical exchanges. We show that not only the tropical Pacific Ocean basin can exhibit coupled ocean-atmosphere interaction, but also the tropical Atlantic and Indian Oceans. Longer lived interactions in the North Pacific and Southern Ocean (the circumpolar wave) are also reviewed. The role of the thermohaline circulation in long-term and abrupt climatic change is examined, with the freshwater budget of the ocean being a key factor for the degree, and longevity, of change. The potential for the Mediterranean outflow to contribute to abrupt change is raised. We end by examining the probability of thermohaline changes in a future of global warming.

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Multiple Equilibria of the Global Thermohaline Circulation

Cited by 246 publications

References 0 publications

The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability

The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability

Inter-ocean fluxes south of Africa in an eddy-permitting model

The role of the oceans in climate

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