The ocean circulation in the southern hemisphere and its climatic impacts in the Eocene

Huber, Matthew; Nof, Doron

doi:10.1016/j.palaeo.2005.07.037

Cited by 121 publications

(130 citation statements)

References 97 publications

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“…Tropical Eocene sea surface temperatures simulated by the fully coupled CCSM1.4 Eocene run of Huber and Nof (2006) were found to be consistent with SST estimates of 33°C (Pearson et al, 2007) from Tanzanian sediments from the Early/Middle Eocene. These mean annual SSTs at 19ºS paleolatitude, were reconstructed based on TEX 86 measurements using the Schouten et al (2003) Fig.…”

Section: Boundary Conditions and Experimental Designsupporting

confidence: 61%

“…Orbital parameters were set to modern day configuration. The EO-AZOLLA simulation was initialized using the atmospheric state from the equilibrium simulation of a fully coupled CCSM1.4 Eocene run (as described in Huber and Nof, 2006). Estimates for Early/Middle Eocene atmospheric pCO 2 are uncertain, varying between~400 and~3 500 ppm (c.f.…”

Section: Boundary Conditions and Experimental Designmentioning

confidence: 99%

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Modeling the influence of a reduced equator-to-pole sea surface temperature gradient on the distribution of water isotopes in the Early/Middle Eocene

Speelman

Sewall

Noone

et al. 2010

Earth and Planetary Science Letters

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Editor: P. DeMenocalKeywords: hydrogen isotopes climate modeling hydrological cycling paleoclimate Eocene Azolla Proxy-based climate reconstructions suggest the existence of a strongly reduced equator-to-pole temperature gradient during the Azolla interval in the Early/Middle Eocene, compared to modern. Changes in the hydrological cycle, as a consequence of a reduced temperature gradient, are expected to be reflected in the isotopic composition of precipitation (δD, δ 18 O). The interpretation of water isotopic records to quantitatively reconstruct past precipitation patterns is, however, hampered by a lack of detailed information on changes in their spatial and temporal distribution. Using the isotope-enabled version of the National Center for Atmospheric Research (NCAR) atmospheric general circulation model, Community Atmosphere Model v.3 (isoCAM3), relationships between water isotopes and past climates can be simulated. Here we examine the influence of an imposed reduced meridional sea surface temperature gradient on the spatial distribution of precipitation and its isotopic composition in an Early/Middle Eocene setting. As a result of the applied forcings, the Eocene simulation predicts the occurrence of less depleted high latitude precipitation, with δD values ranging only between 0 and −140‰ (compared to Present-day 0 to −300‰).Comparison with Early/Middle Eocene-age isotopic proxy data shows that the simulation accurately captures the main features of the spatial distribution of the isotopic composition of Early/Middle Eocene precipitation over land in conjunction with the aspects of the modeled Early/Middle Eocene climate. Hence, the included stable isotope module quantitatively supports the existence of a reduced meridional temperature gradient during this interval.

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Section: Boundary Conditions and Experimental Designsupporting

confidence: 61%

Section: Boundary Conditions and Experimental Designmentioning

confidence: 99%

Modeling the influence of a reduced equator-to-pole sea surface temperature gradient on the distribution of water isotopes in the Early/Middle Eocene

Speelman

Sewall

Noone

et al. 2010

Earth and Planetary Science Letters

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“…A long-held view is that this permitted the development of the Antarctic Circumpolar Current, which introduced conditions favorable for glaciation (i.e., cooler temperatures and increased precipitation) (Kennett, 1977). In addition, recent climate modeling studies have suggested that a reduction in atmospheric greenhouse gases may have played an important role in the triggering of Antarctic glaciation (DeConto and Pollard, 2003;Huber and Nof, 2006). Critical dates for the development of ocean gateways are ~33 Ma, when a significant seaway opened up between Antarctica and Australia (Stickley et al, 2004), and ~31 Ma, when Drake Strait between the Antarctic Peninsula and South America became a significant seaway (Lawver and Gahagan, 2003).…”

Section: Wider Contextmentioning

confidence: 99%

Landscape evolution of Antarctica

Jamieson¹,

Sugden²

2007

Open-File Report

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The relative roles of fluvial versus glacial processes in shaping the landscape of Antarctica have been debated since the expeditions of Robert Scott and Ernest Shackleton in the early years of the 20th century. Here we build a synthesis of Antarctic landscape evolution based on the geomorphology of passive continental margins and former northern mid-latitude Pleistocene ice sheets. What makes Antarctica so interesting is that the terrestrial landscape retains elements of a record of change that extends back to the Oligocene. Thus there is the potential to link conditions on land with those in the oceans and atmosphere as the world switched from a greenhouse to a glacial world and the Antarctic ice sheet evolved to its present state. In common with other continental fragments of Gondwana there is a fluvial signature to the landscape in the form of the coastal erosion surfaces and escarpments, incised river valleys, and a continent-wide network of river basins. A selective superimposed glacial signature reflects the presence or absence of ice at the pressure melting point. Earliest continental-scale ice sheets formed around 34 Ma, growing from local ice caps centered on mountain massifs, and featured phases of ice-sheet expansion and contraction. These ice masses were most likely cold-based over uplands and warm-based across lowlands and near their margins. For 20 million years ice sheets fluctuated on Croll-Milankovitch frequencies. At ~14 Ma the ice sheet expanded to its maximum and deepened a preexisting radial array of troughs selectively through the coastal mountains and eroded the continental shelf before retreating to its present dimensions at ~13.5 Ma. Subsequent changes in ice extent have been forced mainly by sea-level change. Weathering rates of exposed bedrock have been remarkably slow at high elevations around the margin of East Antarctica under the hyperarid polar climate of the last ~13.5 Ma, offering potential for a long quantitative record of ice-sheet evolution with techniques such as cosmogenic isotope analysis.

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“…These values are similar to, or slightly higher than, other late Palaeocene and Eocene floral, faunal and isotopic proxy evidence for mean annual temperature in the Arctic [22][23][24][25][26] . Among several hypotheses to explain such high-latitude warmth, the leading (and not incompatible) two are increased heat transport and increased atmospheric greenhouse gas concentrations, as well as their associated feedbacks [27][28][29][30] .…”

mentioning

confidence: 99%