Limits...
Ocean lead at the termination of the Younger Dryas cold spell.

Pearce C, Seidenkrantz MS, Kuijpers A, Massé G, Reynisson NF, Kristiansen SM - Nat Commun (2013)

Bottom Line: The origin of this rapid, severe cooling episode is still widely debated, but it was probably triggered by a large freshwater influx to the North Atlantic resulting in disruption of the Atlantic Meridional Overturning Circulation.The YD termination, despite having been even more abrupt than the onset has, however, received significantly less attention.Our data indicate a stepwise sequence of events with changes in ocean circulation clearly preceding those in atmospheric conditions, in contrast to the hitherto commonly assumed single-event rapid climatic shift at the YD-Holocene transition.

View Article: PubMed Central - PubMed

Affiliation: Centre for Past Climate Studies, Department of Geoscience, Aarhus University, Høegh-Guldbergs Gade 2, 8000 Aarhus, Denmark. christof.pearce@geo.au.dk

ABSTRACT
The Younger Dryas (YD) cold interval is one of the most abrupt climate events of Earth's recent history. The origin of this rapid, severe cooling episode is still widely debated, but it was probably triggered by a large freshwater influx to the North Atlantic resulting in disruption of the Atlantic Meridional Overturning Circulation. The YD termination, despite having been even more abrupt than the onset has, however, received significantly less attention. Here using multi-proxy data from a high-resolution marine sediment record, we present evidence for a gradual decrease of the Labrador Current influence, northward migration of the Gulf Stream oceanic front and a rapid decline of sea-ice cover at the YD termination. Our data indicate a stepwise sequence of events with changes in ocean circulation clearly preceding those in atmospheric conditions, in contrast to the hitherto commonly assumed single-event rapid climatic shift at the YD-Holocene transition.

No MeSH data available.


Related in: MedlinePlus

Age-depth model for core AI07-14G.The model starts from 78 cm depth in the core and is based on six radiocarbon measurements (Table 1). Light and dark green areas illustrate the 68% and 95% probability range, respectively. cal. yr BP, calibrated years before present.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3644072&req=5

f2: Age-depth model for core AI07-14G.The model starts from 78 cm depth in the core and is based on six radiocarbon measurements (Table 1). Light and dark green areas illustrate the 68% and 95% probability range, respectively. cal. yr BP, calibrated years before present.

Mentions: Our reconstruction of the sequence of events at the YD termination is based on the analysis of marine sediment core AI07-14G from 239 m water depth in Placentia Bay, Newfoundland (Fig. 1). The age of the core ranges from ca. 10–13 kyr BP (thousand years before present, defined as AD 1950) with an average chronological resolution of 6.3 years cm−1 (Fig. 2), allowing the study of the YD–Holocene transition at a sub-decadal temporal resolution. The core was investigated using a multi-proxy approach consisting of sedimentological, micropaleontological and geochemical analyses (Fig. 3). The Ca/Sr ratio, calculated from X-ray fluorescence core scan measurements, was used to identify the presence of a peak in detrital carbonate, associated with H0 around 11.6 kyr BP141516. The presence of H0 was confirmed by X-ray diffraction (XRD) analyses, which showed increased concentrations of calcite and dolomite within the carbonate peak, characteristic of H0 sediments17. Fossil diatom assemblages were used to infer past surface-water conditions and provide information on the relative influence of the main ocean currents. Thalassiosira gravida, an arctic cold-water diatom species, documents the influence of the LC, whereas the warmer-water species Thalassionema nitzschioides was used to track the influence of GS waters1819. The abundance of IP25, a biomarker synthesized by diatoms living in sea ice2021, was measured to reconstruct past variability in spring sea-ice cover.


Ocean lead at the termination of the Younger Dryas cold spell.

Pearce C, Seidenkrantz MS, Kuijpers A, Massé G, Reynisson NF, Kristiansen SM - Nat Commun (2013)

Age-depth model for core AI07-14G.The model starts from 78 cm depth in the core and is based on six radiocarbon measurements (Table 1). Light and dark green areas illustrate the 68% and 95% probability range, respectively. cal. yr BP, calibrated years before present.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3644072&req=5

f2: Age-depth model for core AI07-14G.The model starts from 78 cm depth in the core and is based on six radiocarbon measurements (Table 1). Light and dark green areas illustrate the 68% and 95% probability range, respectively. cal. yr BP, calibrated years before present.
Mentions: Our reconstruction of the sequence of events at the YD termination is based on the analysis of marine sediment core AI07-14G from 239 m water depth in Placentia Bay, Newfoundland (Fig. 1). The age of the core ranges from ca. 10–13 kyr BP (thousand years before present, defined as AD 1950) with an average chronological resolution of 6.3 years cm−1 (Fig. 2), allowing the study of the YD–Holocene transition at a sub-decadal temporal resolution. The core was investigated using a multi-proxy approach consisting of sedimentological, micropaleontological and geochemical analyses (Fig. 3). The Ca/Sr ratio, calculated from X-ray fluorescence core scan measurements, was used to identify the presence of a peak in detrital carbonate, associated with H0 around 11.6 kyr BP141516. The presence of H0 was confirmed by X-ray diffraction (XRD) analyses, which showed increased concentrations of calcite and dolomite within the carbonate peak, characteristic of H0 sediments17. Fossil diatom assemblages were used to infer past surface-water conditions and provide information on the relative influence of the main ocean currents. Thalassiosira gravida, an arctic cold-water diatom species, documents the influence of the LC, whereas the warmer-water species Thalassionema nitzschioides was used to track the influence of GS waters1819. The abundance of IP25, a biomarker synthesized by diatoms living in sea ice2021, was measured to reconstruct past variability in spring sea-ice cover.

Bottom Line: The origin of this rapid, severe cooling episode is still widely debated, but it was probably triggered by a large freshwater influx to the North Atlantic resulting in disruption of the Atlantic Meridional Overturning Circulation.The YD termination, despite having been even more abrupt than the onset has, however, received significantly less attention.Our data indicate a stepwise sequence of events with changes in ocean circulation clearly preceding those in atmospheric conditions, in contrast to the hitherto commonly assumed single-event rapid climatic shift at the YD-Holocene transition.

View Article: PubMed Central - PubMed

Affiliation: Centre for Past Climate Studies, Department of Geoscience, Aarhus University, Høegh-Guldbergs Gade 2, 8000 Aarhus, Denmark. christof.pearce@geo.au.dk

ABSTRACT
The Younger Dryas (YD) cold interval is one of the most abrupt climate events of Earth's recent history. The origin of this rapid, severe cooling episode is still widely debated, but it was probably triggered by a large freshwater influx to the North Atlantic resulting in disruption of the Atlantic Meridional Overturning Circulation. The YD termination, despite having been even more abrupt than the onset has, however, received significantly less attention. Here using multi-proxy data from a high-resolution marine sediment record, we present evidence for a gradual decrease of the Labrador Current influence, northward migration of the Gulf Stream oceanic front and a rapid decline of sea-ice cover at the YD termination. Our data indicate a stepwise sequence of events with changes in ocean circulation clearly preceding those in atmospheric conditions, in contrast to the hitherto commonly assumed single-event rapid climatic shift at the YD-Holocene transition.

No MeSH data available.


Related in: MedlinePlus