Warm saline bottom water in the ancient ocean

Brass, Garrett W.; Southam, John R.; Peterson, W. H.

doi:10.1038/296620a0

Cited by 341 publications

(120 citation statements)

References 8 publications

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“…This perhaps reflects cessa tion of temperate conditions on Maud Rise and replacement by subpolar conditions (Kennett and Kennett, this volume). Com parison with other regions also suggests that, during the late Eocene, the Earth was still characterized by warm, equable cli mates with relatively low pole-to-equator temperature gradients (Kennett, 1977;Wolfe, 1978;Frakes, 1979;Brass et al, 1982).…”

Section: Late Eocene: Further Coolingmentioning

confidence: 99%

“…The occurrence of warm, saline deep waters in the geologic past was anticipated by Chamberlin in 1906 and later considered to be feasible in modeling experiments carried out by Brass et al (1982). These conclusions were based upon the assumption that, at some time in the past, the polar regions (including the Weddell Sea) may have been too warm to provide a major source of cold, deep waters to the ocean basins.…”

Section: Paleogene Deep Water Formation: High or Lowmentioning

confidence: 99%

See 1 more Smart Citation

Latest Cretaceous to Cenozoic Climate and Oceanographic Developments in the Weddell Sea, Antarctica: an Ocean-Drilling Perspective

Kennett¹,

Barker²

1990

Proceedings of the Ocean Drilling Program

162

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Section: Late Eocene: Further Coolingmentioning

confidence: 99%

Section: Paleogene Deep Water Formation: High or Lowmentioning

confidence: 99%

Latest Cretaceous to Cenozoic Climate and Oceanographic Developments in the Weddell Sea, Antarctica: an Ocean-Drilling Perspective

Kennett¹,

Barker²

1990

Proceedings of the Ocean Drilling Program

162

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“…Further, Kennett and Stott (1989) and Zachos et al (1989b) suggest that the oceans may have been characterized by warm, saline bottom water that formed under the sub-tropical highs, perhaps in the Tethys, and moved poleward in the deep ocean. In the past, this sort of salinity-driven ocean circulation has been postulated for the warm Cretaceous (Brass et al, 1982). However, Woodruff and Savin (1989) have demonstrated that warm, saline waters may have been a significant component of ocean deep waters as recently as the early Miocene.…”

Section: Oceanic and Atmospheric Circulation And The Early Eocenementioning

confidence: 99%

Global change at the Paleocene-Eocene boundary: climatic and evolutionary consequences of tectonic events

Rea

Zachos

Owen

et al. 1990

Palaeogeography, Palaeoclimatology, Palaeoecology

194

101

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Rea, D. K., Zachos, J. C., Owen, R. M. and Gingerich, P. D., 1990. Global change at the Paleocene-Eocene boundary:climatic and evolutionary consequences of tectonic events. Palaeogeogr., Palaeoclimatol., Palaeoecol., 79: 117-128.Events of the Paleocene-Eocene boundary provide the clearest example to date of how a tectonic event may have global climatic consequences. Recent advances permit well-constrained stratigraphic determination of several events that occurred at that boundary, in chron C24R: a many-fold increase in sea-floor hydrothermal activity, a global warming, a reduction in the intensity of atmospheric circulation, a conversion to salinity-driven deep ocean circulation, a marked lightening of oceanic 313C values, extinction and evolution of both benthic foraminifera and land mammals, and important plate-boundary reorganizations including the outpouring of the east Greenland volcanics and the initiation of the oceanic rift between Norway and Greenland.We hypothesize that enhanced sea-floor hydrothermal activity occasioned by global tectonism resulted in a flooding of the atmosphere with COz, causing a reduced pole-to-equator temperature gradient and increased evaporation at low latitudes. Increased formation of warm, salty, probably low-nutrient waters coupled with the warm temperatures at high latitudes occasioned a salinity-driven, rather than temperature-driven, deep-water circulation. This newly-evolved ocean circulation pattern changed the apportionment of global heat transport from the atmosphere to the ocean, with concomitant changes in the circulation intensity of both. Reduced intensity of atmospheric circulation resulted in lower oceanic biological productivity and enhanced seasonality of climate on the continents. A major extinction event among benthic foraminifera was probably a response to the new low-nutrient and chemically changed bottom waters, and endemism following rapid evolution and dispersal of mammalian orders may have been in response to the new continental climate regime.

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“…An example of this occurring could be on a planet whose atmosphere is considerably denser than that of Earth, which results in a significantly smaller equator-pole temperature gradient (8,24). This idea has featured in attempts to explain the evidence for the presence of warm deep water in the Cretaceous, hypothesized to be the result of significantly higher evaporation rates rather than a higher mean salinity (25).…”

Section: Resultsmentioning

confidence: 99%

Importance of ocean salinity for climate and habitability

Cullum

Stevens

Joshi

2016

Proc. Natl. Acad. Sci. U.S.A.

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Modeling studies of terrestrial extrasolar planetary climates are now including the effects of ocean circulation due to a recognition of the importance of oceans for climate; indeed, the peak equatorpole ocean heat transport on Earth peaks at almost half that of the atmosphere. However, such studies have made the assumption that fundamental oceanic properties, such as salinity, temperature, and depth, are similar to Earth. This assumption results in Earth-like circulations: a meridional overturning with warm water moving poleward at the surface, being cooled, sinking at high latitudes, and traveling equatorward at depth. Here it is shown that an exoplanetary ocean with a different salinity can circulate in the opposite direction: an equatorward flow of polar water at the surface, sinking in the tropics, and filling the deep ocean with warm water. This alternative flow regime results in a dramatic warming in the polar regions, demonstrated here using both a conceptual model and an ocean general circulation model. These results highlight the importance of ocean salinity for exoplanetary climate and consequent habitability and the need for its consideration in future studies.exoplanet | habitability | planetary climate | ocean circulation W ith the ongoing discovery of exoplanets, it is natural to question their habitability. The most widely accepted definition of a habitable planet is one that can sustain liquid water on its surface (1), which usually implies a range of orbital radii in which a planet receives a level of stellar radiation that enables surface liquid water to be sustained (2, 3). Habitability and climate also depend on heat being transported effectively around the planet, which is achieved through the circulation of the atmosphere and ocean. There are many studies describing simulations of exoplanetary atmospheric circulations and climate (4), but most incorporate either no ocean (5-7) or a heavily simplified slab ocean (8-12). Only recently have studies considered a dynamical ocean (13-16), and even in these studies, the ocean is consistently assumed to have similar properties to the oceans on Earth. Such an assumption may prove to be an oversimplification. More recently changes in ocean properties have begun to be investigated, for example, ocean depth (17), and here, salinity, which has significant influence on density.There is evidence on Earth that the mean ocean salinity has decreased from up to double the present day level since the Archean (18,19). In addition, modeling of water delivery during planetary formation concludes that there could be an extensive range of possible ocean masses (20,21). Planets in the habitable zone may have oceans with a small fraction to hundreds of times the volume of the oceans on Earth, which will have important implications for the geological evolution of the planet and the salinity of any oceans. Ocean salinity can also be influenced by planetary properties, for example, the immense pressures at the floor of a very deep ocean could maintain a layer of ice at...

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Warm saline bottom water in the ancient ocean

Cited by 341 publications

References 8 publications

Latest Cretaceous to Cenozoic Climate and Oceanographic Developments in the Weddell Sea, Antarctica: an Ocean-Drilling Perspective

Latest Cretaceous to Cenozoic Climate and Oceanographic Developments in the Weddell Sea, Antarctica: an Ocean-Drilling Perspective

Global change at the Paleocene-Eocene boundary: climatic and evolutionary consequences of tectonic events

Importance of ocean salinity for climate and habitability

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