(NAS Colloquium) Carbon Dioxide and Climate Change (1997) / Chapter Skim
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Pages 90-97
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From page 90... ...
Keeling, held November 13-15, 1995, at the National Academy of Sciences, Irvine, CA. A long marine history of carbon cycle modulation by orbital-climatic changes TIMOTHY D
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From page 91... ...
By itself, such a transfer would have tended to promote a higher CO2 content of the atmosphere. Ice core records, however, indicate the reverse; the paradox must be resolved by changes in the carbon cycle in the ocean that favor increasing carbon storage in the ocean during glacial periods.
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From page 92... ...
that this cycle has been an important paleoclimatic frequency since the inception of glaciation in the Southern Hemisphere at the end of the Eocene Epoch, ~33.5 Ma. Low Frequency Components in the Tertiary Carbon Cycle The importance of 100-kyr cyclicity in the late Pleistocene is a puzzle in the Milankovitch theory of climate.
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From page 93... ...
and deeper locations, it seems likely that they reflect in large part changes in the productivity of calcareous organisms rather than in the alkalinity of deep waters. Simple models of sediment accumulation suggest that the carbonate cycles reflect increases both in carbonate accumulation (high carbonate beds)
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From page 94... ...
can be applied to other mid-Cretaceous ocean basins because studies of pelagic sediments outcropping in the Mediterranean region and recovered by deep-sea drilling show similar patterns (40~. Time series sampling demonstrates that organic carbonenriched beds fall in a consistent position in a hierarchy of sedimentary oscillations linked to orbital forcing.
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From page 95... ...
The organic carbon-enriched layers are actually impoverished in the remains of hard parts of the marine plankton. The covariance of both siliceous and carbonate deposition makes it unlikely, therefore, that the carbonate oscillations reflect changes in the saturation state of the deep basin waters.
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From page 96... ...
For the carbon cycle, small changes in the density structure of deep waters can modulate the basin-basin fractionation of alkalinity and nutrients (cf.
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From page 97... ...
(1985) in The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present, eds.
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