Low-latitude climate variability in the Heinrich frequency band of the Late Cretaceous greenhouse world

Abstract. Deep marine successions of early Campanian age from DSDP (Deep Sea Drilling Project) site 516F drilled at low paleolatitudes in the South Atlantic reveal distinct sub-Milankovitch variability in addition to precession, obliquity and eccentricity-related variations. Elemental abundance ratios point to a similar climatic origin for these variations and exclude a quadripartite structure as an explanation for the inferred semi-precession cyclicity in the magnetic susceptibility (MS) signal as observed in the Mediterranean Neogene for precession-related cycles. However, semi-precession cycles as suggested by previous work are likely an artifact reflecting the first harmonic of the precession signal. The sub-Milankovitch variability, especially in MS, is best approximated by a ~7 kyr cycle as shown by spectral analysis and bandpass filtering. The presence of sub-Milankovitch cycles with a period similar to that of Heinrich events of the last glacial cycle is consistent with linking the latter to low-latitude climate change caused by a non-linear response to precession-induced variations in insolation between the tropics.

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Low-latitude climate variability in the Heinrich frequency band of the Late Cretaceous Greenhouse world

Climate of the Past Discussions ◽

10.5194/cpd-9-4475-2013 ◽

2013 ◽

Vol 9 (4) ◽

pp. 4475-4498 ◽

Cited By ~ 1

Author(s):

N. J. de Winter ◽

C. Zeeden ◽

F. J. Hilgen

Keyword(s):

Linear Response ◽

Elemental Abundance ◽

Milankovitch Cycles ◽

Glacial Cycle ◽

Low Latitude ◽

Heinrich Events ◽

Precession Cycle ◽

The Tropics ◽

The Last Glacial ◽

Dsdp Site

Abstract. Deep marine successions of early Campanian age from DSDP site 516F drilled at low paleolatitudes in the South Atlantic reveal distinct sub-Milankovitch variability in addition to precession and eccentricity related variations. Elemental abundance ratios point to a similar climatic origin for these variations and exclude a quadripartite structure – as observed in the Mediterranean Neogene – of the precession related cycles as an explanation for the inferred semi-precession cyclicity in MS. However, the semi-precession cycle itself is likely an artifact, reflecting the first harmonic of the precession signal. The sub-Milankovitch variability is best approximated by a ~ 7 kyr cycle as shown by spectral analysis and bandpass filtering. The presence of sub-Milankovitch cycles with a period similar to that of Heinrich events of the last glacial cycle is consistent with linking the latter to low-latitude climate change caused by a non-linear response to precession induced variations in insolation between the tropics.

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Carbon burial in deep-sea sediment and implications for oceanic inventories of carbon and alkalinity over the last glacial cycle

Climate of the Past ◽

10.5194/cp-14-1819-2018 ◽

2018 ◽

Vol 14 (11) ◽

pp. 1819-1850 ◽

Cited By ~ 11

Author(s):

Olivier Cartapanis ◽

Eric D. Galbraith ◽

Daniele Bianchi ◽

Samuel L. Jaccard

Keyword(s):

Marine Sediments ◽

Active Carbon ◽

Deep Sea ◽

Dissolved Inorganic Carbon ◽

Glacial Cycle ◽

Last Glacial ◽

Carbon Burial ◽

Order Constraint ◽

The Last Glacial ◽

Carbon Inventory

Abstract. Although it has long been assumed that the glacial–interglacial cycles of atmospheric CO2 occurred due to increased storage of CO2 in the ocean, with no change in the size of the “active” carbon inventory, there are signs that the geological CO2 supply rate to the active pool varied significantly. The resulting changes of the carbon inventory cannot be assessed without constraining the rate of carbon removal from the system, which largely occurs in marine sediments. The oceanic supply of alkalinity is also removed by the burial of calcium carbonate in marine sediments, which plays a major role in air–sea partitioning of the active carbon inventory. Here, we present the first global reconstruction of carbon and alkalinity burial in deep-sea sediments over the last glacial cycle. Although subject to large uncertainties, the reconstruction provides a first-order constraint on the effects of changes in deep-sea burial fluxes on global carbon and alkalinity inventories over the last glacial cycle. The results suggest that reduced burial of carbonate in the Atlantic Ocean was not entirely compensated by the increased burial in the Pacific basin during the last glacial period, which would have caused a gradual buildup of alkalinity in the ocean. We also consider the magnitude of possible changes in the larger but poorly constrained rates of burial on continental shelves, and show that these could have been significantly larger than the deep-sea burial changes. The burial-driven inventory variations are sufficiently large to have significantly altered the δ13C of the ocean–atmosphere carbon and changed the average dissolved inorganic carbon (DIC) and alkalinity concentrations of the ocean by more than 100 µM, confirming that carbon burial fluxes were a dynamic, interactive component of the glacial cycles that significantly modified the size of the active carbon pool. Our results also suggest that geological sources and sinks were significantly unbalanced during the late Holocene, leading to a slow net removal flux on the order of 0.1 PgC yr−1 prior to the rapid input of carbon during the industrial period.

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