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.

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 Eastern Andean environmental and climate synthesis for the last 2000 years BP from terrestrial pollen and charcoal records of Patagonia

2015 ◽  
Vol 11 (3) ◽  
pp. 2121-2157 ◽  
Author(s):  
G. D. Sottile ◽  
M. E. Echeverria ◽  
M. V. Mancini ◽  
M. M. Bianchi ◽  
M. A. Marcos ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Environmental Changes ◽  
Fire Regime ◽  
Ice Age ◽  
Circulation System ◽  
Forest Steppe ◽  
Proxy Records ◽  
The Andes ◽  
Precipitation Regimes ◽  
Southern Patagonia

Abstract. The Southern Hemisphere Westerly Winds (SWW) constitute an important zonal circulation system that dominates the dynamics of Southern Hemisphere mid-latitude climate. Little is known about climatic changes in the Southern South America in comparison to the Northern Hemisphere due to the low density of proxy records, and adequate chronology and sampling resolution to address environmental changes of the last 2000 years. Since 2009, new pollen and charcoal records from bog and lakes in northern and southern Patagonia at the east side of the Andes have been published with an adequate calibration of pollen assemblages related to modern vegetation and ecological behaviour. In this work we improve the chronological control of some eastern Andean previously published sequences and integrate pollen and charcoal dataset available east of the Andes to interpret possible environmental and SWW variability at centennial time scales. Through the analysis of modern and past hydric balance dynamics we compare these scenarios with other western Andean SWW sensitive proxy records for the last 2000 years. Due to the distinct precipitation regimes that exist between Northern (40–45° S) and Southern Patagonia (48–52° S) pollen sites locations, shifts on latitudinal and strength of the SWW results in large changes on hydric availability on forest and steppe communities. Therefore, we can interpret fossil pollen dataset as changes on paleohydric balance at every single site by the construction of paleohydric indices and comparison to charcoal records during the last 2000 cal yrs BP. Our composite pollen-based Northern and Southern Patagonia indices can be interpreted as changes in latitudinal variation and intensity of the SWW respectively. Dataset integration suggest poleward SWW between 2000 and 750 cal yrs BP and northward-weaker SWW during the Little Ice Age (750–200 cal yrs BP). These SWW variations are synchronous to Patagonian fire activity major shifts. We found an in phase fire regime (in terms of timing of biomass burning) between northern Patagonia Monte shrubland and Southern Patagonia steppe environments. Conversely, there is an antiphase fire regime between Northern and Southern Patagonia forest and forest-steppe ecotone environments. SWW variability may be associated to ENSO variability especially during the last millennia. For the last 200 cal yrs BP we can concluded that the SWW belt were more intense and poleward than the previous interval. Our composite pollen-based SWW indices show the potential of pollen dataset integration to improve the understanding of paleohydric variability especially for the last 2000 millennial in Patagonia.

Pattern and Forcing of Northern Hemisphere Glacier Variations During the Last Millennium

1986 ◽  
Vol 26 (1) ◽  
pp. 27-48 ◽  
Author(s):  
Stephen C. Porter
Keyword(s):  
Northern Hemisphere ◽  
Little Ice Age ◽  
Ice Core ◽  
Volcanic Eruptions ◽  
Ice Age ◽  
Phase Lag ◽  
Mountain Glacier ◽  
Radiocarbon Dates ◽  
Glacier Fluctuations ◽  
Decadal Scale

Time series depicting mountain glacier fluctuations in the Alps display generally similar patterns over the last two centuries, as do chronologies of glacier variations for the same interval from elsewhere in the Northern Hemisphere. Episodes of glacier advance consistently are associated with intervals of high average volcanic aerosol production, as inferred from acidity variations in a Greenland ice core. Advances occur whenever acidity levels rise sharply from background values to reach concentrations ≥1.2 μequiv H+/kg above background. A phase lag of about 10–15 yr, equivalent to reported response lags of Alpine glacier termini, separates the beginning of acidity increases from the beginning of subsequent ice advances. A similar relationship, but based on limited and less-reliable historical data and on lichenometric ages, is found for the preceding 2 centuries. Calibrated radiocarbon dates related to advances of non-calving and non-surging glaciers during the earlier part of the Little Ice Age display a comparable consistent pattern. An interval of reduced acidity values between about 1090 and 1230 A.D. correlates with a time of inferred glacier contraction during the Medieval Optimum. The observed close relation between Noothern Hemisphere glacier fluctuations and variations in Greenland ice-core acidity suggests that sulfur-rich aerosols generated by volcanic eruptions are a primary forcing mechanism of glacier fluctuations, and therefore of climate, on a decadal scale. The amount of surface cooling attributable to individual large eruptions or to episodes of eruptions is simlar to the probable average temperature reduction during culminations of Little Ice Age alacier advances (ca. 0.5°–1.2°C), as inferred from depression of equilibrium-line altitudes.

scholarly journals Glacier response to North Atlantic climate variability during the Holocene

2015 ◽  
Vol 11 (3) ◽  
pp. 2009-2036 ◽  
Author(s):  
N. L. Balascio ◽  
W. J. D'Andrea ◽  
R. S. Bradley
Keyword(s):  
Climate Variability ◽  
20Th Century ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
Late Holocene ◽  
North Atlantic Ocean ◽  
The Holocene ◽  
The Past ◽  
Summer Insolation ◽  
Geochemical Parameters

Abstract. Small glaciers and ice caps respond rapidly to climate variations and records of their past extent provide information on the natural envelope of past climate variability. Millennial-scale trends in Holocene glacier size are well documented and correspond with changes in Northern Hemisphere summer insolation. However, there is only sparse and fragmentary evidence for higher frequency variations in glacier size because in many Northern Hemisphere regions glacier advances of the past few hundred years were the most extensive and destroyed the geomorphic evidence of ice growth and retreat during the past several thousand years. Thus, most glacier records have been of limited use for investigating centennial scale climate forcing and feedback mechanisms. Here we report a continuous record of glacier activity for the last 9.5 ka from southeast Greenland, derived from high-resolution measurements on a proglacial lake sediment sequence. Physical and geochemical parameters show that the glaciers responded to previously documented Northern Hemisphere climatic excursions, including the "8.2 ka" cooling event, the Holocene Thermal Maximum, Neoglacial cooling, and 20th Century warming. In addition, the sediments indicate centennial-scale oscillations in glacier size during the late Holocene. Beginning at 4.1 ka, a series of abrupt glacier advances occurred, each lasting ~100 years and followed by a period of retreat, that were superimposed on a gradual trend toward larger glacier size. Thus, while declining summer insolation caused long-term cooling and glacier expansions during the late Holocene, climate system dynamics resulted in repeated episodes of glacier expansion and retreat on multi-decadal to centennial timescales. These episodes coincided with ice rafting events in the North Atlantic Ocean and periods of regional ice cap expansion, which confirms their regional significance and indicates that considerable glacier activity on these timescales is a normal feature of the cryosphere. The data provide a longer-term perspective on the rate of 20th century glacier retreat and indicate that recent anthropogenic-driven warming has already impacted the regional cryosphere in a manner outside the natural range of Holocene variability.

scholarly journals Glacier response to Holocene warmth inferred from in situ <sup>10</sup>Be and <sup>14</sup>C bedrock analyses in Steingletscher’s forefield (central Swiss Alps)

2021 ◽  
Author(s):  
Irene Schimmelpfennig ◽  
Joerg Schaefer ◽  
Jennifer Lamp ◽  
Vincent Godard ◽  
Roseanne Schwartz ◽  
...  
Keyword(s):  
Warm Season ◽  
Summer Temperature ◽  
Swiss Alps ◽  
Ice Age ◽  
European Alps ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Mountain Glaciers ◽  
Driving Mechanisms

Abstract. Mid-latitude mountain glaciers sensitively respond to local summer temperature changes. Chronologies of past glacier fluctuations based on the investigation of glacial landforms therefore allows for a better understanding of warm-season climate variability at local scale. In this study, we focus on the Holocene, the current interglacial of the last 11,700 years, which remains matter of dispute regarding its temperature evolution and underlying driving mechanisms. In particular, the nature and significance of the transition from the early to mid-Holocene and of the Holocene Thermal Maximum (HTM) are still debated. Here, we apply a new approach by combining in situ cosmogenic 10Be moraine and 10Be-14C bedrock dating from the same site, the forefield of Steingletscher (European Alps), and reconstruct the glacier’s millennial recession and advance periods. The results suggest that subsequent to the final deglaciation at ~10 ka, the glacier was mostly smaller than its 2000 CE extent until ~3 ka, followed by the predominant occurrence of glacier advances until the end of the Little Ice Age in the 19th century. These findings agree with existing proxy records of Holocene summer temperature and glacier evolution in the Alps, showing that glaciers throughout the region retreated beyond modern extents for most of the Early and mid-Holocene. This implies that at least the summer climate of the HTM was warmer than that of the end of the 20th century for several millennia. Further investigations are necessary to refine the magnitude of warming and the potential HTM seasonality.

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.

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 Glacier response to Holocene warmth inferred from in situ <sup>10</sup>Be and <sup>14</sup>C bedrock analyses in Steingletscher's forefield (central Swiss Alps)

2022 ◽  
Vol 18 (1) ◽  
pp. 23-44
Author(s):  
Irene Schimmelpfennig ◽  
Joerg M. Schaefer ◽  
Jennifer Lamp ◽  
Vincent Godard ◽  
Roseanne Schwartz ◽  
...  
Keyword(s):  
Swiss Alps ◽  
Ice Age ◽  
European Alps ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Mountain Glaciers ◽  
Driving Mechanisms ◽  
Summer Temperatures ◽  
The Alps

Abstract. Mid-latitude mountain glaciers are sensitive to local summer temperature changes. Chronologies of past glacier fluctuations based on the investigation of glacial landforms therefore allow for a better understanding of natural climate variability at local scale, which is relevant for the assessment of the ongoing anthropogenic climate warming. In this study, we focus on the Holocene, the current interglacial of the last 11 700 years, which remains a matter of dispute regarding its temperature evolution and underlying driving mechanisms. In particular, the nature and significance of the transition from the early to mid-Holocene and of the Holocene Thermal Maximum (HTM) are still debated. Here, we apply an emerging approach by combining in situ cosmogenic 10Be moraine and 10Be–14C bedrock dating from the same site, the forefield of Steingletscher (European Alps), and reconstruct the glacier's millennial recession and advance periods. The results suggest that, subsequent to the final deglaciation at ∼10 ka, the glacier was similar to or smaller than its 2000 CE extent for ∼7 kyr. At ∼3 ka, Steingletscher advanced to an extent slightly outside the maximum Little Ice Age (LIA) position and until the 19th century experienced sizes that were mainly confined between the LIA and 2000 CE extents. These findings agree with existing Holocene glacier chronologies and proxy records of summer temperatures in the Alps, suggesting that glaciers throughout the region were similar to or even smaller than their 2000 CE extent for most of the early and mid-Holocene. Although glaciers in the Alps are currently far from equilibrium with the accelerating anthropogenic warming, thus hindering a simple comparison of summer temperatures associated with modern and paleo-glacier sizes, our findings imply that the summer temperatures during most of the Holocene, including the HTM, were similar to those at the end of the 20th century. Further investigations are necessary to refine the magnitude of warming and the potential HTM seasonality.

scholarly journals Sedimentary archives of climate and sea-level changes during the Holocene in the Rhone prodelta (NW Mediterranean Sea)

2016 ◽  
Author(s):  
Anne-Sophie Fanget ◽  
Maria-Angela Bassetti ◽  
Christophe Fontanier ◽  
Alina Tudryn ◽  
Serge Berné
Keyword(s):  
Sea Level ◽  
Water Depth ◽  
Late Holocene ◽  
Ice Age ◽  
Sea Level Changes ◽  
The Holocene ◽  
The Core ◽  
Core Site ◽  
Nw Mediterranean ◽  
And Sea Level

Abstract. A 7.38 m-long sediment core was collected from the eastern part of the Rhone prodelta (NW Mediterranean) at 67 m water depth. A multi-proxy study (sedimentary facies, benthic foraminifera and ostracods, clay mineralogy, and major elements from XRF) provides a multi-decadal to century-scale record of climate and sea-level changes during the Holocene. The early Holocene is marked by alternative silt and clay layers interpreted as distal tempestites deposited in a context of rising sea level. This interval contains shallow infra-littoral benthic meiofauna (e.g. Pontocythere elongata, Elphidium spp., Quinqueloculina lata) and formed between ca. 20 and 50 m water depth. The middle Holocene (ca. 8.3 to 4.5 ka cal. BP), is characterized, at the core site, by a period of sediment starvation (accumulation rate of ca. 0.01 cm yr−1) resulting from the maximum landward shift of the shoreline and the Rhone outlet(s). From a sequence stratigraphic point of view, this condensed interval, about 35 cm-thick, is a Maximum Flooding Surface that can be identified on seismic profiles as the transition between delta retrogradation and delta progradation. It is marked by very distinct changes in all proxy records. Following the stabilization of the global sea level, the late Holocene is marked by the establishment of prodeltaic conditions at the core site, as shown by the lithofacies and by the presence of benthic meiofauna typical of the modern Rhone prodelta (e.g. Valvulineria bradyana, Cassidulina carinata, Bulimina marginata). Several periods of increased fluvial discharge are also emphasized by the presence of species commonly found in brackish and shallow water environments (e.g. Leptocythere). Some of these periods correspond to the multi-decadal to centennial late Holocene humid periods recognized in Europe (i.e. the 2.8 ka event and the Little Ice Age). Two other periods of increased runoffs at ca. 1.3 and 1.1 ka cal. BP are recognized, and are likely to reflect periods of regional climate deterioration that are observed in the Rhone watershed.

Global Ice-Sheet System Interlocked by Sea Level

1986 ◽  
Vol 26 (1) ◽  
pp. 3-26 ◽  
Author(s):  
George H. Denton ◽  
Terence J. Hughes ◽  
Wibjörn Karlén
Keyword(s):  
Carbon Dioxide ◽  
Sea Level ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
High Frequency ◽  
Atmospheric Carbon Dioxide ◽  
Ice Sheet ◽  
Ice Age ◽  
Atmospheric Carbon

Denton and Hughes (1983, Quaternary Research 20, 125–144) postulated that sea level linked a global ice-sheet system with both terrestrial and grounded marine components during late Quaternary ice ages. Summer temperature changes near Northern Hemisphere melting margins initiated sea-level fluctuations that controlled marine components in both polar hemispheres. It was further proposed that variations of this ice-sheet system amplified and transmitted Milankovitch summer half-year insolation changes between 45 and 75°N into global climatic changes. New tests of this hypothesis implicate sea level as a major control of the areal extent of grounded portions of the Antarctic Ice Sheet, thus fitting the concept of a globally interlocked ice-sheet system. But recent atmospheric modeling results (Manabe and Broccoli, 1985, Journal of Geophysical Research 90, 2167–2190) suggest that factors other than areal changes of the grounded Antarctic Ice Sheet strongly influenced Southern Hemisphere climate and terminated the last ice age simultaneously in both polar hemispheres. Atmospheric carbon dioxide linked to high-latitude oceans is the most likely candidate (Shackleton and Pisias, 1985, Atmospheric carbon dioxide, orbital forcing, and climate. In “The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present” (E. T. Sundquest and W. S. Broecker, Eds.), pp. 303–318. Geophysical Monograph 32, American Geophysical Union, Washington, D.C.), but another potential influence was high-frequency climatic oscillations (2500 yr). It is postulated that variations in atmospheric carbon dioxide acted through an Antarctic ice shelf linked to the grounded ice sheet to produce and terminate Southern Hemisphere ice-age climate. It is further postulated that Milankovitch summer insolation combined with a warm high-frequency oscillation caused marked recession of Northern Hemisphere ice-sheet melting margins and the North Atlantic polar front about 14,000 14C yr B.P. This permitted renewed formation of North Atlantic Deep Water, which could well have controlled atmospheric carbon dioxide (W. S. Broecker, D. M. Peteet, and D. Rind, 1985, Nature (London) 315, 21–26). Combined melting and consequent sea-level rise from the three warming factors initiated irreversible collapse of the interlocked global ice-sheet system, which was at its largest but most vulnerable configuration.

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