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1

Digitale Medien

Tectonic forcing of late Cenozoic climate (1992)

Raymo, M. E. ; Ruddiman, W. F.

[s.l.] : Nature Publishing Group

Nature 359 (1992), S. 117-122

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ISSN: 1476-4687

Quelle: Nature Archives 1869 - 2009

Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik

Notizen: [Auszug] Global cooling in the Cenozoic, which led to the growth of large continental ice sheets in both hemispheres, may have been caused by the uplift of the Tibetan plateau and the positive feedbacks initiated by this event. In particular, tectonically driven increases in chemical weathering may have ...

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1038/359117a0

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Digitale Medien

Evidence bearing on the mechanism of rapid deglaciation (1990)

Ruddiman, W. F. ; Molfino, B. ; Esmay, A. ; [weitere]

Springer

Climatic change 3 (1990), S. 65-87

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ISSN: 1573-1480

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: Abstract Six northeast Atlantic cores contain planktonic foraminiferal records implying a very abrupt glacial/interglacial surface-ocean warming roughly coincident with the last deglaciation (isotopic termination II) at 127 000 yr B.P. These faunal composition curves have, however, been substantially altered by sediment mixing processes on the sea floor; they are translated downward in the core record and made to look steeper than they actually were. The reason for this abnormally large mixing impact is an interval of sediment with very low to negligible concentrations of all microfossils (surface ocean and bottom living). These low concentrations reflect a several-thousand-year interval of low productivity and little or no life in the overlying surface waters. We interpret this thorough suppression of productivity as a consequence of meltwater and icebergs flooding into the subpolar Atlantic gyre from the surrounding Northern Hemisphere ice sheets during deglaciation. The meltwater influx inhibited warm-season productivity by maintaining a well-stratified low-salinity surface layer; in winter, the low salinity layer froze, stopping nutrientrich deep waters from surfacing in normal cold-season convection. The earth's orbital configuration during this deglaciation created an unusually strong summer insolation maximum and winter insolation minimum in the Northern Hemisphere. Rapid melting and disintegration of the Northern Hemisphere ice sheets induced by strong summer insolation apparently created the meltwater influx; combined with very low winter insolation, the presence of this low-salinity meltwater layer led to unusually extensive sea-ice formation. The existence of a large region of winter sea ice across the subpolar North Atlantic during deglaciation implies a reduced supply of moisture in winter to the wasting Northern Hemisphere ice sheets. This includes the loss of winter moisture both locally from ice-covered northern waters and regionally from low-latitude winter storms no longer penetrating northward. The winter sea-ice cover thus acts as an amplifier providing positive feedback to the insolation-driven deglaciation process.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00144986

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Digitale Medien

Evidence bearing on the mechanism of rapid deglaciation (1980)

Ruddiman, W. F. ; Molfino, B. ; Esmay, A. ; [weitere]

Springer

Climatic change 3 (1980), S. 65-87

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ISSN: 1573-1480

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: Abstract Six northeast Atlantic cores contain planktonic foraminiferal records implying a very abrupt glacial/interglacial surface-ocean warming roughly coincident with the last deglaciation (isotopic termination II) at 127 000 yr B.P. These faunal composition curves have, however, been substantially altered by sediment mixing processes on the sea floor; they are translated downward in the core record and made to look steeper than they actually were. The reason for this abnormally large mixing impact is an interval of sediment with very low to negligible concentrations of all microfossils (surface ocean and bottom living). These low concentrations reflect a several-thousand-year interval of low productivity and little or no life in the overlying surface waters. We interpret this thorough suppression of productivity as a consequence of meltwater and icebergs flooding into the subpolar Atlantic gyre from the surrounding Northern Hemisphere ice sheets during deglaciation. The meltwater influx inhibited warm-season productivity by maintaining a well-stratified low-salinity surface layer; in winter, the low salinity layer froze, stopping nutrientrich deep waters from surfacing in normal cold-season convection. The earth's orbital configuration during this deglaciation created an unusually strong summer insolation maximum and winter insolation minimum in the Northern Hemisphere. Rapid melting and disintegration of the Northern Hemisphere ice sheets induced by strong summer insolation apparently created the meltwater influx; combined with very low winter insolation, the presence of this low-salinity meltwater layer led to unusually extensive sea-ice formation. The existence of a large region of winter sea ice across the subpolar North Atlantic during deglaciation implies a reduced supply of moisture in winter to the wasting Northern Hemisphere ice sheets. This includes the loss of winter moisture both locally from ice-covered northern waters and regionally from low-latitude winter storms no longer penetrating northward. The winter sea-ice cover thus acts as an amplifier providing positive feedback to the insolation-driven deglaciation process.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02423169

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Northern Hemisphere Climate Regimes During the Past 3 Ma: Possible Tectonic Connections (1988)

Ruddiman, W. F. ; Raymo, M. E.

Royal Society of London

In: Philosophical Transactions of the Royal Society B: Biological Sciences, 318 (1191). pp. 411-430.

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Publikationsdatum: 2020-06-11

Beschreibung: The 100 ka rhythm of orbital eccentricity has dominated large-amplitude climatic variations in the high-latitude North Atlantic during the Brunhes magnetic chron (0-0.735 Ma BP). Earlier, during the Matuyama chron (0.735-2.47 Ma BP), climatic variations in this region were lower in amplitude and concentrated mainly at the 41 ka rhythm of orbital obliquity. These rhythmic climatic responses to orbital forcing are evident both in stable isotopic (δ18O) indicators of ice volume or temperature and in biotic and lithologic indicators of local North Atlantic surfaceocean variability. The synchronous responses of these indicators are consistent with results from atmospheric general circulation models showing that the North American ice sheet directly controls North Atlantic surface-ocean responses via strong cold winds that are generated on the northern ice-sheet flanks and blow out across the ocean, chilling its surface. Before 2.47 Ma BP, smaller-scale quasiperiodic oscillations of the planktonic fauna and flora occurred, but the cause of these variations in the absence of significant ice sheets is unclear.

Materialart: Article , PeerReviewed

Format: text

DOI: 10.1098/rstb.1988.0017

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