scholarly journals Radiocarbon/Tree-Ring Calibration, Solar Activity, and Upwelling of Ocean Water

Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 987-995 ◽  
Author(s):  
F B Knox ◽  
B G McFadgen
Keyword(s):  
Solar Activity ◽  
Tree Ring ◽  
North Atlantic ◽  
Little Ice Age ◽  
Ice Age ◽  
Calibration Data ◽  
Ocean Water ◽  
Smooth Curves ◽  
The North ◽  
Oceanic Upwelling

Least-squares fitted smooth curves to radiocarbon versus tree-ring calibration data for the period AD 1140 to 1950 are compared with climatic warming and cooling of the North Atlantic (Little Ice Age), and with recorded sunspot numbers over the period AD 1670 to 1950.Calibration curves from different parts of the globe are not identical, and appear to be determined by a combination of variable solar activity and variable oceanic upwelling of 14C-depleted water, with the variable upwelling itself partly determined by solar activity.

scholarly journals Tree-ring radiocarbon reveals reduced solar activity during Younger Dryas cooling

2020 ◽  
Author(s):  
Adam Sookdeo ◽  
Bernd Kromer ◽  
Florian Adolphi ◽  
Jürg Beer ◽  
Nicolas Brehm ◽  
...  
Keyword(s):  
Solar Activity ◽  
Tree Ring ◽  
North Atlantic ◽  
Little Ice Age ◽  
Ice Core ◽  
Younger Dryas ◽  
Ice Age ◽  
The North ◽  
Long Duration ◽  
Clear Sign

<p>The Younger Dryas stadial (YD) was a return to glacial-like conditions in the North Atlantic region that interrupted deglacial warming around 12900 cal BP (before 1950 AD). Terrestrial and marine records suggest this event was initiated by the interruption of deep-water formation arising from North American freshwater runoff, but the causes of the millennia-long duration remain unclear. To investigate the solar activity, a possible YD driver, we exploit the cosmic production signals of tree-ring radiocarbon (<sup>14</sup>C) and ice-core beryllium-10 (<sup>10</sup>Be). Here we present the highest temporally resolved dataset of <sup>14</sup>C measurements (n = 1558) derived from European tree rings that have been accurately extended back to 14226 cal BP (±8, 2-σ), allowing precise alignment of ice-core records across this period. We identify a substantial increase in <sup>14</sup>C and <sup>10</sup>Be production starting at 12780 cal BP is comparable in magnitude to the historic Little Ice Age, being a clear sign of grand solar minima. We hypothesize the timing of the grand solar minima provides a significant amplifying factor leading to the harsh sustained glacial-like conditions seen in the YD.</p>

scholarly journals Bunker Cave stalagmites: an archive for central European Holocene climate variability

2012 ◽  
Vol 8 (3) ◽  
pp. 1687-1720 ◽  
Author(s):  
J. Fohlmeister ◽  
A. Schröder-Ritzrau ◽  
D. Scholz ◽  
C. Spötl ◽  
D. F. C. Riechelmann ◽  
...  
Keyword(s):  
Climate Variability ◽  
North Atlantic ◽  
Little Ice Age ◽  
Ice Age ◽  
Holocene Climate ◽  
Central European ◽  
The North ◽  
The North Atlantic ◽  
Meteoric Precipitation ◽  
Precipitation And Temperature

Abstract. Holocene climate was characterised by variability on multi-centennial to multi-decadal time scales. In central Europe, these fluctuations were most pronounced during winter. Here we present a new record of past winter climate variability for the last 10.8 ka based on four speleothems from Bunker Cave, Western Germany. Due to its central European location, the cave site is particularly well suited to record changes in precipitation and temperature in response to changes in the North Atlantic realm. We present high resolution records of δ18O, δ13C values and Mg/Ca ratios. We attribute changes in the Mg/Ca ratio to variations in the meteoric precipitation. The stable C isotope composition of the speleothems most likely reflects changes in vegetation and precipitation and variations in the δ18O signal are interpreted as variations in meteoric precipitation and temperature. We found cold and dry periods between 9 and 7 ka, 6.5 and 5.5 ka, 4 and 3 ka as well as between 0.7 to 0.2 ka. The proxy signals in our stalagmites compare well with other isotope records and, thus, seem representative for central European Holocene climate variability. The prominent 8.2 ka event and the Little Ice Age cold events are both recorded in the Bunker cave record. However, these events show a contrasting relationship between climate and δ18O, which is explained by different causes underlying the two climate anomalies. Whereas the Little Ice Age is attributed to a pronounced negative phase of the North Atlantic Oscillation, the 8.2 ka event was triggered by cooler conditions in the North Atlantic due to a slowdown of the Thermohaline Circulation.

Cuban stalagmite suggests relationship between Caribbean precipitation and the Atlantic Multidecadal Oscillation during the past 1.3 ka

The Holocene ◽  
2012 ◽  
Vol 22 (12) ◽  
pp. 1405-1412 ◽  
Author(s):  
Claudia Fensterer ◽  
Denis Scholz ◽  
Dirk Hoffmann ◽  
Christoph Spötl ◽  
Jesús M Pajón ◽  
...  
Keyword(s):  
North Atlantic ◽  
Little Ice Age ◽  
Rainfall Intensity ◽  
Thermohaline Circulation ◽  
Atlantic Multidecadal Oscillation ◽  
Ice Age ◽  
The Past ◽  
The North ◽  
Southward Shift ◽  
The North Atlantic

Here we present the first high-resolution δ18O record of a stalagmite from western Cuba. The record reflects precipitation variability in the northwestern Caribbean during the last 1.3 ka and exhibits a correlation to the Atlantic Multidecadal Oscillation (AMO). This suggests a relationship between Caribbean rainfall intensity and North Atlantic sea-surface temperature (SST) anomalies. A potential mechanism for this relationship may be the strength of the Thermohaline Circulation (THC). For a weaker THC, lower SSTs in the North Atlantic possibly lead to a southward shift of the Intertropical Convergence Zone and drier conditions in Cuba. Thus, this Cuban stalagmite records drier conditions during cold phases in the North Atlantic such as the ‘Little Ice Age’. This study contributes to the understanding of teleconnections between North Atlantic SSTs and northern Caribbean climate variability during the past 1.3 ka.

scholarly journals Late Holocene climate variability in the southwestern Mediterranean region: an integrated marine and terrestrial geochemical approach

2010 ◽  
Vol 6 (5) ◽  
pp. 1655-1683 ◽  
Author(s):  
C. Martín-Puertas ◽  
F. Jiménez-Espejo ◽  
F. Martínez-Ruiz ◽  
V. Nieto-Moreno ◽  
M. Rodrigo ◽  
...  
Keyword(s):  
Climate Variability ◽  
North Atlantic ◽  
Little Ice Age ◽  
Mediterranean Region ◽  
Late Holocene ◽  
Western Mediterranean ◽  
Warm Period ◽  
Ice Age ◽  
The North ◽  
The North Atlantic

Abstract. A combination of marine (Alboran Sea cores, ODP 976 and TTR 300 G) and terrestrial (Zoñar Lake, Andalucia, Spain) paleoclimate information using geochemical proxies provides a high resolution reconstruction of climate variability and human influence in southwestern Mediterranean region for the last 4000 years at inter-centennial resolution. Proxies respond to changes in precipitation rather than temperature alone. Our archive documents a succession of dry and wet periods coherent with the North Atlantic climate signal. Drier stages occurred prior to 2.7 cal ka BP, well-correlated with the global aridity crisis of the third-millennium BC, and during the Medieval Warm Period (1.4–0.7 cal ka BP). Wetter conditions prevailed from 2.7 to 1.4 cal ka BP and after the Medieval Warm Period and the onset of the Little Ice Age. Hydrological signatures during the Little Ice Age are highly variable but consistent with more humidity that the period before. Additionally, Pb anomalies in sediments at the end of Bronze Age suggest anthropogenic pollution earlier than the Roman Empire development in the Iberian Peninsula. The evolution of the climate in the study area during the Late Holocene confirms the see-saw pattern previously shown between eastern and western Mediterranean regions and suggests a higher influence of the North Atlantic dynamics in the western Mediterranean.

scholarly journals The origin of glacial alpine landscape in Tröllaskagi Peninsula (North Iceland)

2016 ◽  
Vol 42 (2) ◽  
pp. 341 ◽  
Author(s):  
N. Andrés ◽  
L. M. Tanarro ◽  
J. M. Fernández ◽  
D. Palacios
Keyword(s):  
North Atlantic ◽  
Little Ice Age ◽  
Ice Age ◽  
Important Advance ◽  
North Central ◽  
The North ◽  
Significant Difference ◽  
Rock Glaciers ◽  
Basalt Plateau ◽  
Tertiary Basalt

The Tröllaskagi peninsula is located in north central Iceland, between meridians 19º30’W and 18º10’W , limited by Skagafjödur fiord to the west and the Eyjafjödur fiord to the east, jutting out into the North Atlantic to latitude 66º12’N and linked to the central Icelandic highlands to the south. The peninsula is a Tertiary basalt plateau topped by flat summits with altitudes of 1000-1500 m, intensely dissected by the drainage network. The aim of this present study is to synthesize the recent advances in our understanding of the landscape and its dynamics in the Tröllaskagi peninsula and find the origin of its significant difference from the rest of Iceland. Results of the most recent research suggest the situation of Tröllaskagi as ice-free, delimited by the two great glacial outlets flowing down from the Icelandic Ice Sheet through the Skagafjödur and Eyjafjödur fiords, from at least the Oldest Dryas to the end of the Early Preboreal. Inland in Tröllaskagi, the glaciers formed in the north-facing cirques without losing their alpine characteristics during the Late Pleistocene and Holocene. The advances of these glaciers during the Oldest, Older and Youngest Dryas and the Early Preboreal were only a few hundred metres greater than the most important advance in the second half of the Holocene, during the Little Ice Age. Only a few of these glaciers remained debris-free and are sensitive to the minor climate oscillations. The rest, due to the important geomorphological activity on their walls, developed into debris-covered and rock glaciers and lost this significant dynamism.

Bivalves indicate that the North Atlantic was under stress before the onset of the Little Ice Age

2021 ◽  
Author(s):  
Beatriz Arellano Nava ◽  
Paul R. Halloran ◽  
Chris A. Boulton ◽  
Timothy M. Lenton
Keyword(s):  
Marine Environment ◽  
North Atlantic ◽  
Little Ice Age ◽  
Stable State ◽  
Volcanic Eruptions ◽  
Ice Age ◽  
Last Millennium ◽  
The North ◽  
Growth Increments ◽  
Negative Feedbacks

<p>The last millennium was characterised by a cooling from the Medieval Warm Period into the Little Ice Age. While strong volcanic eruptions could have triggered the onset of the Little Ice Age by reducing solar irradiance, modelling experiments suggest that it was amplified and maintained by sea ice-ocean feedbacks, including a potential abrupt weakening of the subpolar gyre. The weakening of negative feedbacks that maintain a system in a stable state, prior to an abrupt transition, can be detected as an increase in temporal autocorrelation and variability. Here we use an annually-resolved and absolutely dated shell-derived record from the North Icelandic Shelf that spans the last millennium, to detect such a loss of resilience in the marine environment leading up to the Little Ice Age transition. We find a significant increase in autocorrelation and variance in bivalve growth increments and oxygen isotopes before the transition, providing evidence consistent with loss of stability in the marine environment. This supports the idea that internal feedbacks played an important role in the Little Ice Age onset.</p>

scholarly journals Bunker Cave stalagmites: an archive for central European Holocene climate variability

2012 ◽  
Vol 8 (5) ◽  
pp. 1751-1764 ◽  
Author(s):  
J. Fohlmeister ◽  
A. Schröder-Ritzrau ◽  
D. Scholz ◽  
C. Spötl ◽  
D. F. C. Riechelmann ◽  
...  
Keyword(s):  
Climate Variability ◽  
North Atlantic ◽  
Little Ice Age ◽  
Ice Age ◽  
Holocene Climate ◽  
Central European ◽  
The North ◽  
The North Atlantic ◽  
Meteoric Precipitation ◽  
Precipitation And Temperature

Abstract. Holocene climate was characterised by variability on multi-centennial to multi-decadal time scales. In central Europe, these fluctuations were most pronounced during winter. Here we present a record of past winter climate variability for the last 10.8 ka based on four speleothems from Bunker Cave, western Germany. Due to its central European location, the cave site is particularly well suited to record changes in precipitation and temperature in response to changes in the North Atlantic realm. We present high-resolution records of δ18O, δ13C values and Mg/Ca ratios. Changes in the Mg/Ca ratio are attributed to past meteoric precipitation variability. The stable C isotope composition of the speleothems most likely reflects changes in vegetation and precipitation, and variations in the δ18O signal are interpreted as variations in meteoric precipitation and temperature. We found cold and dry periods between 8 and 7 ka, 6.5 and 5.5 ka, 4 and 3 ka as well as between 0.7 and 0.2 ka. The proxy signals in the Bunker Cave stalagmites compare well with other isotope records and, thus, seem representative for central European Holocene climate variability. The prominent 8.2 ka event and the Little Ice Age cold events are both recorded in the Bunker Cave record. However, these events show a contrasting relationship between climate and δ18O, which is explained by different causes underlying the two climate anomalies. Whereas the Little Ice Age is attributed to a pronounced negative phase of the North Atlantic Oscillation, the 8.2 ka event was triggered by cooler conditions in the North Atlantic due to a slowdown of the thermohaline circulation.

Slope Water Current over the Laurentian Fan on Interannual to Millennial Time Scales

Science ◽  
1999 ◽  
Vol 286 (5439) ◽  
pp. 520-523 ◽  
Author(s):  
L. D. Keigwin ◽  
R. S. Pickart
Keyword(s):  
North Atlantic ◽  
Gulf Stream ◽  
Little Ice Age ◽  
Coupled System ◽  
Ice Age ◽  
Water Current ◽  
Sea Level Pressure ◽  
Ocean Variability ◽  
The North ◽  
The North Atlantic Oscillation

The strength and position of surface and deep currents in the slope water south of Newfoundland are thought to vary as a coupled system in relation to the dipole in atmospheric sea level pressure known as the North Atlantic oscillation (NAO). Paleoceanographic data from the Laurentian Fan, used as a proxy for sea surface temperature, reveal that surface slope waters north of the Gulf Stream experienced warming during the Little Ice Age of the 16th to 19th centuries and support the notion of an NAO-driven coupled system. The NAO may be a useful model for millennial-scale ocean variability during interglacial climate states.

scholarly journals Hydrological evidence for a North Atlantic oscillation during the Little Ice Age outside its range observed since 1850

2011 ◽  
Vol 7 (6) ◽  
pp. 4149-4171 ◽  
Author(s):  
C. Martín-Puertas ◽  
I. Dorado-Liñán ◽  
A. Brauer ◽  
E. Zorita ◽  
B. L. Valero-Garcés ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Little Ice Age ◽  
Stable Carbon Isotope ◽  
Low Frequency ◽  
Ice Age ◽  
The South ◽  
Activity Maximum ◽  
The North ◽  
The North Atlantic

Abstract. An annual-resolved precipitation reconstruction for the last 800 yr in Southern Spain has been performed using stable carbon isotope (δ13C) of Pinus nigra tree rings. The reconstruction exhibits high- to low-frequency variability and distinguishes a Little Ice Age (LIA, AD 1350–1850) characterized by lower averaged rainfall than both in the transition from the Medieval Climate Anomaly to the LIA and in the 20th century. The driest conditions are recorded during the Maunder solar Minimum (mid 17th–early 18th centuries), in good agreement with the Spanish documentary archive. Similar linkage between solar activity (maximum/minimum) and precipitation (increase/decrease) is observed throughout the entire LIA. Additionally, the relationship between the hydrological pattern in the Iberian Peninsula and Morocco during the LIA suggests different spatial distribution of precipitation in the south-eastern sector of the North Atlantic region such as it is known currently. Whereas in the instrumental record the precipitation evolves similarly in both regions and opposite to the North Atlantic oscillation (NAO) index, the coldest periods of the LIA shows a contrasting pattern with drier conditions in the South of Spain and wetter in Northern Africa. We suggest an extreme negative NAO conditions, accompanied by a southward excursion of the winter rainfall band beyond that observed in the last century, can explain this contrast. The sustained NAO conditions could have been triggered by solar minima and higher volcanic activity during the LIA.

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