Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation

Rahmstorf, Stefan; Box, Jason E.; Feulner, Georg; Mann, Michael; Robinson, Alexander; Rutherford, Scott; Schaffernicht, Erik

doi:10.1038/nclimate2554

Cited by 855 publications

(853 citation statements)

References 52 publications

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“…Yet these reconstructions generally disagree with the one in Lund et al (2006). Rahmstorf et al (2015), for example, showed instead an AMOC weakening during the industrial period as compared to the LIA, in agreement with results from instrumental records (Dima and Lohmann 2010) and CMIP5 historical model simulations (Drijfhout et al 2012;Cheng et al 2013;Jungclaus et al 2014). These latter however generally disagree on the mechanisms underlying the AMOC variability, as well as on the AMOC sensitivity to external forcing (e.g., Servonnat et al 2010;Ortega et al 2012;Hofer et al 2011).…”

Section: Introductionsupporting

confidence: 66%

“…Some reconstructions simply rely on the use of geological proxy archives to some extent sensitive to changes in the AMOC or its components (e.g., Wanamaker et al 2012;Dylmer et al 2013). Others are based on model-based covariances between the AMOC and other oceanic variables that are easier to quantify, like Labrador Sea deep densities (Robson et al 2014) or mean surface temperatures in the warming hole region (Rahmstorf et al 2015). Yet these reconstructions generally disagree with the one in Lund et al (2006).…”

Section: Introductionmentioning

confidence: 99%

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Assessing reconstruction techniques of the Atlantic Ocean circulation variability during the last millennium

et al. 2016

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the simulated variability at deep/shallow levels. Density changes responsible for the pseudo-reconstructed FCT are mainly driven by zonal temperature differences; salinity differences oppose but play a minor role. These results thus support the use of the thermal-wind relationship to reconstruct the oceanic circulation past variability, in particular at multidecadal timescales. Yet model-data comparison highlights important differences between the simulated and the proxy-based FCT variability. ECHO-G simulates a prominent weakening in the North Atlantic circulation that contrasts with the reconstructed enhancement. Our model results thus do not support the reconstructed FC minimum during the Little Ice Age. This points to a failure in the reconstruction, misrepresented processes in the model, or an important role of internal ocean dynamics.

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Section: Introductionsupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Assessing reconstruction techniques of the Atlantic Ocean circulation variability during the last millennium

et al. 2016

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“…In the abyssal realm, seafloor habitats under areas of deep-water formation (e.g., those in the North Atlantic and Southern Oceans) could experience a maximum decline in O 2 concentration of 0.03 mL L -1 by 2100 (i.e., a 0.5% drop from current levels; Tables 2, 3; Figures 2, 3). Greenhouse warming may also exert an effect on abyssal O 2 levels (as well as pH and temperature) by changing thermohaline circulation (Rahmstorf et al, 2015;Yamamoto et al, 2015). Reduced Atlantic Ocean overturning circulation will initially lead to lower O 2 levels at the deep seafloor, and may alter the intensity of Pacific and Indian Ocean OMZs (Schmittner et al, 2007).…”

Section: Oxygenationmentioning

confidence: 99%

Major impacts of climate change on deep-sea benthic ecosystems

Sweetman

Thurber

Smith

et al. 2017

Elementa: Science of the Anthropocene

282

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The deep sea encompasses the largest ecosystems on Earth. Although poorly known, deep seafloor ecosystems provide services that are vitally important to the entire ocean and biosphere. Rising atmospheric greenhouse gases are bringing about significant changes in the environmental properties of the ocean realm in terms of water column oxygenation, temperature, pH and food supply, with concomitant impacts on deep-sea ecosystems. Projections suggest that abyssal (3000-6000 m) ocean temperatures could increase by 1°C over the next 84 years, while abyssal seafloor habitats under areas of deep-water formation may experience reductions in water column oxygen concentrations by as much as 0.03 mL L -1 by 2100. Bathyal depths (200-3000 m) worldwide will undergo the most significant reductions in pH in all oceans by the year 2100 (0.29 to 0.37 pH units). O 2 concentrations will also decline in the bathyal NE Pacific and Southern Oceans, with losses up to 3.7% or more, especially at intermediate depths. Another important environmental parameter, the flux of particulate organic matter to the seafloor, is likely to decline significantly in most oceans, most notably in the abyssal and bathyal Indian Ocean where it is predicted to decrease by 40-55% by the end of the century. Unfortunately, how these major changes will affect deep-seafloor ecosystems is, in some cases, very poorly understood. In this paper, we provide a detailed overview of the impacts of these changing environmental parameters on deep-seafloor ecosystems that will most likely be seen by 2100 in continental margin, abyssal and polar settings. We also consider how these changes may combine with other anthropogenic stressors (e.g., fishing, mineral mining, oil and gas extraction) to further impact deep-seafloor ecosystems and discuss the possible societal implications.

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“…Such cooling is likely related to a slowdown of the Atlantic meridional overturning circulation (AMOC). Several observational studies (e.g., Rahmstorf et al 2015;Kelly et al 2016) have documented that a slowdown of the AMOC has already begun to occur in the 20th century, particularly after 1970.…”

Section: Climate Change Projectionsmentioning

confidence: 99%

Dynamical downscaling with the fifth-generation Canadian regional climate model (CRCM5) over the CORDEX Arctic domain: effect of large-scale spectral nudging and of empirical correction of sea-surface temperature

et al. 2017

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most notable positive effect over the Arctic is a reduction of the T2m bias over the North Pacific Ocean and the North Atlantic Ocean in all seasons. Future projections using this method are compared with the results obtained with the traditional 2-step dynamical downscaling (CGCM-RCM) to assess the impact of correcting systematic biases of SST upon future-climate projections. The future projections are mostly similar for the two methods, except for precipitation.

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Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation

Cited by 855 publications

References 52 publications

Assessing reconstruction techniques of the Atlantic Ocean circulation variability during the last millennium

Assessing reconstruction techniques of the Atlantic Ocean circulation variability during the last millennium

Major impacts of climate change on deep-sea benthic ecosystems

Dynamical downscaling with the fifth-generation Canadian regional climate model (CRCM5) over the CORDEX Arctic domain: effect of large-scale spectral nudging and of empirical correction of sea-surface temperature

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