scholarly journals Bayesian Evaluation of the Southern Hemisphere Radiocarbon Offset during the Holocene

Radiocarbon ◽  
2009 ◽  
Vol 51 (4) ◽  
pp. 1165-1176 ◽  
Author(s):  
Alan Hogg ◽  
Christopher Bronk Ramsey ◽  
Chris Turney ◽  
Jonathan Palmer
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Calibration Curve ◽  
Early Holocene ◽  
Data Sets ◽  
Bayesian Calibration ◽  
The Holocene ◽  
Calibration Program

While an interhemispheric offset in atmospheric radiocarbon levels from AD 1950–950 is now well established, its existence earlier in the Holocene is less clear, with some studies reporting globally uniform 14C levels while others finding Southern Hemisphere samples older by a few decades. In this paper, we present a method for wiggle-matching Southern Hemisphere data sets against Northern Hemisphere curves, using the Bayesian calibration program OxCal 4.1 with the Reservoir Offset function accommodating a potential interhemispheric offset. The accuracy and robustness of this approach is confirmed by wiggle-matching known-calendar age sequences of the Southern Hemisphere calibration curve SHCal04 against the Northern Hemisphere curve IntCal04. We also show that 5 of 9 Holocene Southern Hemisphere data sets are capable of yielding reliable offset information. Those data sets that are accurate and precise show that interhemispheric offset levels in the Early Holocene are similar to modern levels, confirming SHCal04 as the curve of choice for calibrating Southern Hemisphere samples.

scholarly journals SHCal20 Southern Hemisphere Calibration, 0–55,000 Years cal BP

Radiocarbon ◽  
2020 ◽  
Vol 62 (4) ◽  
pp. 759-778 ◽  
Author(s):  
Alan G Hogg ◽  
Timothy J Heaton ◽  
Quan Hua ◽  
Jonathan G Palmer ◽  
Chris SM Turney ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Tree Ring ◽  
Calibration Curve ◽  
Data Sets ◽  
Errors In Variables ◽  
Time Intervals ◽  
Tree Ring Data ◽  
The Mean ◽  
Statistical Approaches

ABSTRACTEarly researchers of radiocarbon levels in Southern Hemisphere tree rings identified a variable North-South hemispheric offset, necessitating construction of a separate radiocarbon calibration curve for the South. We present here SHCal20, a revised calibration curve from 0–55,000 cal BP, based upon SHCal13 and fortified by the addition of 14 new tree-ring data sets in the 2140–0, 3520–3453, 3608–3590 and 13,140–11,375 cal BP time intervals. We detail the statistical approaches used for curve construction and present recommendations for the use of the Northern Hemisphere curve (IntCal20), the Southern Hemisphere curve (SHCal20) and suggest where application of an equal mixture of the curves might be more appropriate. Using our Bayesian spline with errors-in-variables methodology, and based upon a comparison of Southern Hemisphere tree-ring data compared with contemporaneous Northern Hemisphere data, we estimate the mean Southern Hemisphere offset to be 36 ± 27 14C yrs older.

scholarly journals Radiocarbon Variations from Tasmanian Conifers: Results from Three Early Holocene Logs

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 361-369 ◽  
Author(s):  
Mike Barbetti ◽  
Trevor Bird ◽  
George Dolezal ◽  
Gillian Taylor ◽  
Roger Francey ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Calibration Curve ◽  
The Other ◽  
Early Holocene ◽  
Conifer Species ◽  
Middle Holocene ◽  
Calibration Curves ◽  
Lagarostrobos Franklinii ◽  
Floodplain Sediments ◽  
Good Coverage

Dendrochronological studies are being carried out on two conifer species in the Stanley River area of western Tasmania. The chronology for Huon pine (Lagarostrobos franklinii), with living trees up to 1400 yr old, extends back to 571 bc. Living celery-top pine (Phyllocladus aspleniifolius) trees are up to 500 yr old. Apart from living or recently felled trees, sections have been taken from 350 subfossil logs preserved in floodplain sediments. They range in age from >38 ka to modern, with good coverage for the periods 9–3.5 ka and from 2.5 ka to the present. We report here on 14C measurements of decadal samples from three early Holocene logs, between 10 and 9 ka bp, providing short (ca. 300-yr) records of atmospheric 14C variations when plotted against ring numbers. The southern hemisphere data from Tasmania can be compared and wiggle-matched with published 14C calibration curves from German oak and pine. One set of measurements covers the period, ca. 9280–8990 cal bp, overlapping the link between the Hohenheim “Main 9” and middle Holocene master oak chronologies. The other sets of measurements from Tasmania coincide; they span the period, ca. 9840–9480 cal bp, overlapping the end of the German Preboreal pine and the beginning of the oak chronologies. Our measurements confirm that this part of the calibration curve is a gently sloping 14C-age plateau (ca. 8900–8700 bp, between 10,000 and 9500 cal bp), and suggest interhemispheric 14C differences close to zero.

scholarly journals The movements of Alpine glaciers throughout the last 10,000 years as sensitive proxies of temperature and climate changes

2020 ◽  
Vol 232 ◽  
pp. 02002
Author(s):  
Walter Kutschera ◽  
Gernot Patzelt ◽  
Joerg M. Schaefer ◽  
Christian Schlüchter ◽  
Peter Steier ◽  
...  
Keyword(s):  
New Zealand ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Climate Changes ◽  
European Alps ◽  
Cosmogenic Isotopes ◽  
The Holocene ◽  
Surface Exposure Dating ◽  
Exposure Dating ◽  
Alpine Glaciers

A brief review of the movements of Alpine glaciers throughout the Holocene in the Northern Hemisphere (European Alps) and in the Southern Hemisphere (New Zealand Southern Alps) is presented. It is mainly based on glacier studies where 14C dating, dendrochronology and surface exposure dating with cosmogenic isotopes is used to establish the chronology of advances and retreats of glaciers. An attempt is made to draw some general conclusions on the temperature and climate differences between the Northern and Southern Hemisphere.

scholarly journals Atmospheric Radiocarbon for the Period 1950–2010

Radiocarbon ◽  
2013 ◽  
Vol 55 (4) ◽  
pp. 2059-2072 ◽  
Author(s):  
Quan Hua ◽  
Mike Barbetti ◽  
Andrzej Z Rakowski
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Tree Ring ◽  
Organic Materials ◽  
Annual Data ◽  
Data Sets ◽  
Model Calculations ◽  
Monthly Data ◽  
Radiocarbon Data ◽  
Global Carbon

We present a compilation of tropospheric 14CO2 for the period 1950–2010, based on published radiocarbon data from selected records of atmospheric CO2 sampling and tree-ring series. This compilation is a new version of the compilation by Hua and Barbetti (2004) and consists of yearly summer data sets for zonal, hemispheric, and global levels of atmospheric 14C. In addition, compiled (and extended) monthly data sets for 5 atmospheric zones (3 in the Northern Hemisphere and 2 in the Southern Hemisphere) are reported. The annual data sets are for use in regional and global carbon model calculations, while the extended monthly data sets serve as calibration curves for 14C dating of recent, short-lived terrestrial organic materials.

scholarly journals Holocene History of Río Tranquilo Glacier, Monte San Lorenzo (47°S), Central Patagonia

2021 ◽  
Vol 9 ◽  
Author(s):  
Esteban A. Sagredo ◽  
Scott A. Reynhout ◽  
Michael R. Kaplan ◽  
Juan C. Aravena ◽  
Paola S. Araya ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Late Holocene ◽  
Time Frame ◽  
Ice Age ◽  
European Alps ◽  
Mountain Glacier ◽  
The Holocene ◽  
San Lorenzo ◽  
Southern Patagonia

The causes underlying Holocene glacier fluctuations remain elusive, despite decades of research efforts. Cosmogenic nuclide dating has allowed systematic study and thus improved knowledge of glacier-climate dynamics during this time frame, in part by filling in geographical gaps in both hemispheres. Here we present a new comprehensive Holocene moraine chronology from Mt. San Lorenzo (47°S) in central Patagonia, Southern Hemisphere. Twenty-four new 10Be ages, together with three published ages, indicate that the Río Tranquilo glacier approached its Holocene maximum position sometime, or possibly on multiple occasions, between 9,860 ± 180 and 6,730 ± 130 years. This event(s) was followed by a sequence of slightly smaller advances at 5,750 ± 220, 4,290 ± 100 (?), 3,490 ± 140, 1,440 ± 60, between 670 ± 20 and 430 ± 20, and at 390 ± 10 years ago. The Tranquilo record documents centennial to millennial-scale glacier advances throughout the Holocene, and is consistent with recent glacier chronologies from central and southern Patagonia. This pattern correlates well with that of multiple moraine-building events with slightly decreasing net extent, as is observed at other sites in the Southern Hemisphere (i.e., Patagonia, New Zealand and Antarctic Peninsula) throughout the early, middle and late Holocene. This is in stark contrast to the typical Holocene mountain glacier pattern in the Northern Hemisphere, as documented in the European Alps, Scandinavia and Canada, where small glaciers in the early-to-mid Holocene gave way to more-extensive glacier advances during the late Holocene, culminating in the Little Ice Age expansion. We posit that this past asymmetry between the Southern and Northern hemisphere glacier patterns is due to natural forcing that has been recently overwhelmed by anthropogenic greenhouse gas driven warming, which is causing interhemispherically synchronized glacier retreat unprecedented during the Holocene.

ATMOSPHERIC RADIOCARBON FOR THE PERIOD 1950–2019

Radiocarbon ◽  
2021 ◽  
pp. 1-23
Author(s):  
Quan Hua ◽  
Jocelyn C Turnbull ◽  
Guaciara M Santos ◽  
Andrzej Z Rakowski ◽  
Santiago Ancapichún ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Tree Rings ◽  
Data Sets ◽  
Previous Approach ◽  
Monthly Data ◽  
Smooth Curves ◽  
Clean Air ◽  
Increasing Demand

ABSTRACT This paper presents a compilation of atmospheric radiocarbon for the period 1950–2019, derived from atmospheric CO2 sampling and tree rings from clean-air sites. Following the approach taken by Hua et al. (2013), our revised and extended compilation consists of zonal, hemispheric and global radiocarbon (14C) data sets, with monthly data sets for 5 zones (Northern Hemisphere zones 1, 2, and 3, and Southern Hemisphere zones 3 and 1–2). Our new compilation includes smooth curves for zonal data sets that are more suitable for dating applications than the previous approach based on simple averaging. Our new radiocarbon dataset is intended to help facilitate the use of atmospheric bomb 14C in carbon cycle studies and to accommodate increasing demand for accurate dating of recent (post-1950) terrestrial samples.

scholarly journals Effects of melting ice sheets and orbital forcing on the early Holocene warming in the extratropical Northern Hemisphere

2016 ◽  
Vol 12 (5) ◽  
pp. 1119-1135 ◽  
Author(s):  
Yurui Zhang ◽  
Hans Renssen ◽  
Heikki Seppä
Keyword(s):  
Northern Hemisphere ◽  
Spatial Patterns ◽  
Regional Differences ◽  
Climate Model ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Early Holocene ◽  
Orbital Forcing ◽  
The Holocene ◽  
Northern Canada

Abstract. The early Holocene is marked by the final transition from the last deglaciation to the relatively warm Holocene. Proxy-based temperature reconstructions suggest a Northern Hemisphere warming, but also indicate important regional differences. Model studies have analyzed the influence of diminishing ice sheets and other forcings on the climate system during the Holocene. The climate response to forcings before 9 kyr BP (referred to hereafter as kyr), however, remains not fully comprehended. We therefore studied, by employing the LOVECLIM climate model, how orbital and ice-sheet forcings contributed to climate change and to these regional differences during the earliest part of the Holocene (11.5–7 kyr). Our equilibrium experiment for 11.5 kyr suggests lower annual mean temperatures at the onset of the Holocene than in the preindustrial era with the exception of Alaska. The magnitude of this cool anomaly varied regionally, and these spatial patterns are broadly consistent with proxy-based reconstructions. Temperatures throughout the whole year in northern Canada and northwestern Europe for 11.5 kyr were 2–5 °C lower than those of the preindustrial era as the climate was strongly influenced by the cooling effect of the ice sheets, which was caused by enhanced surface albedo and ice-sheet orography. In contrast, temperatures in Alaska for all seasons for the same period were 0.5–3 °C higher than the control run, which were caused by a combination of orbital forcing and stronger southerly winds that advected warm air from the south in response to prevailing high air pressure over the Laurentide Ice Sheet (LIS). The transient experiments indicate a highly inhomogeneous early Holocene temperature warming over different regions. The climate in Alaska was constantly cooling over the whole Holocene, whereas there was an overall fast early Holocene warming in northern Canada by more than 1 °C kyr−1 as a consequence of progressive LIS decay. Comparisons of simulated temperatures with proxy records illustrate uncertainties related to the reconstruction of ice-sheet melting, and such a kind of comparison has the potential to constrain the uncertainties in ice-sheet reconstruction. Overall, our results demonstrate the variability of the climate during the early Holocene, both in terms of spatial patterns and temporal evolution.

Speleothem records of changes in tropical hydrology over the Holocene and possible implications for atmospheric methane

The Holocene ◽  
2011 ◽  
Vol 21 (5) ◽  
pp. 735-741 ◽  
Author(s):  
Stephen J. Burns
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Methane Production ◽  
Methane Emissions ◽  
Atmospheric Methane ◽  
Direct Response ◽  
The Holocene ◽  
Tropical Hydrology ◽  
The Tropics ◽  
Methane Concentrations

Recent speleothem records from the tropics of both hemispheres document a gradual decrease in the intensity of the monsoons in the Northern Hemisphere and increase in the Southern Hemisphere monsoons over the Holocene. These changes are a direct response of the monsoons to precession-driven insolation variability. With regard to atmospheric methane, this shift should result in a decrease in Northern Hemisphere tropical methane emissions and increase in Southern Hemisphere emissions. It is plausible that that overall tropical methane production experienced a minimum in the mid-Holocene because of decreased seasonality in rainfall at the margins of the tropics. Changes in tropical methane production alone might, therefore, explain many of the characteristics of Holocene methane concentrations and isotopic chemistry.

scholarly journals 14C Calibration in the Southern Hemisphere and the Date of the Last Taupo Eruption: Evidence from Tree-Ring Sequences

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 155-163 ◽  
Author(s):  
R. J. Sparks ◽  
W. H. Melhuish ◽  
J.W. A. McKee ◽  
John Ogden ◽  
J. G. Palmer ◽  
...  
Keyword(s):  
New Zealand ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Tree Ring ◽  
Tree Rings ◽  
Calibration Curve ◽  
Systematic Difference ◽  
Calibration Data ◽  
Northern And Southern Hemispheres

Tree rings from a section of Prumnopitys taxifolia (matai) covering the period ad 1335–1745 have been radiocarbon dated and used to generate a 14C calibration curve for southern hemisphere wood. Comparison of this curve with calibration data for northern hemisphere wood does not show a systematic difference between 14C ages measured in the northern and southern hemispheres. A floating chronology covering 270 yr and terminating at the last Taupo (New Zealand) eruption, derived from a sequence of 10-yr samples of tree rings from Phyllocladus trichomanoides (celery pine, or tanekaha), is also consistent with the absence of a systematic north-south difference, and together with the matai data, fixes the date of the Taupo eruption at ad 232 ± 15.

scholarly journals SHCal13 Southern Hemisphere Calibration, 0–50,000 Years cal BP

Radiocarbon ◽  
2013 ◽  
Vol 55 (4) ◽  
pp. 1889-1903 ◽  
Author(s):  
Alan G Hogg ◽  
Quan Hua ◽  
Paul G Blackwell ◽  
Mu Niu ◽  
Caitlin E Buck ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Calibration Curve ◽  
Younger Dryas ◽  
Autoregressive Process ◽  
Measured Data ◽  
Data Sets ◽  
Short Term ◽  
Data Set ◽  
Radiocarbon Calibration

The Southern Hemisphere SHCal04 radiocarbon calibration curve has been updated with the addition of new data sets extending measurements to 2145 cal BP and including the ANSTO Younger Dryas Huon pine data set. Outside the range of measured data, the curve is based upon the ern Hemisphere data sets as presented in IntCal13, with an interhemispheric offset averaging 43 ± 23 yr modeled by an autoregressive process to represent the short-term correlations in the offset.

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