scholarly journals Cryogenic cave carbonates in the Dolomites (Northern Italy): insights into Younger Dryas cooling and seasonal precipitation

2020 ◽  
Author(s):  
Gabriella Koltai ◽  
Christoph Spötl ◽  
Hai Cheng
Keyword(s):  
Freezing Point ◽  
Younger Dryas ◽  
Negative Temperature ◽  
Northern Italy ◽  
Ice Age ◽  
Thermal Modelling ◽  
European Alps ◽  
Shallow Subsurface ◽  
Geomorphic Features ◽  
Glacier Advance

Abstract. In the European Alps, the Younger Dryas (YD) was characterized by the last major glacier advance with equilibrium line altitudes being ~ 220 to 290 m lower than during the Little Ice Age and also by the development of rock glaciers. Dating of these geomorphic features, however, is associated with substantial uncertainties leading to considerable ambiguities on the internal structure of this stadial, the most intensively studied one of the last glacial period. Here we provide robust physical evidence based on precise 230Th-dated cryogenic cave carbonates (CCC) coupled with thermal modelling indicating that early YD winters were only moderately cold in the Southern Alps, challenging the commonly held view of extreme YD seasonality. Our data argue for a negative temperature anomaly of ≤ 3 °C in mean annual air temperature at the Allerød-YD transition in a mountain cave (Cioccherloch, 2274 m a.s.l.) in the Dolomites of northern Italy. Our data suggest that autumns and early winters in the early part of the YD were relatively snow-rich, resulting in a stable winter snow cover. The latter insulated the shallow subsurface in winter and allowed the cave interior to remain close to the freezing point (0 °C) year-round, promoting CCC formation. The main phase of CCCs precipitation at ~ 12.2 ka BP coincides with the mid-YD transition recorded in other archives across Europe. Based on thermal modelling we propose that CCC formation at ~ 12.2 ka BP was most likely associated with a slight warming of approximately +1 °C in conjunction with drier autumns and early winters in the second half of the YD. These changes triggered CCC formation in this alpine cave as well as ice glacier retreat and rock glacier expansion in the Alps.

scholarly journals Cryogenic cave carbonates in the Dolomites (northern Italy): insights into Younger Dryas cooling and seasonal precipitation

2021 ◽  
Vol 17 (2) ◽  
pp. 775-789
Author(s):  
Gabriella Koltai ◽  
Christoph Spötl ◽  
Alexander H. Jarosch ◽  
Hai Cheng
Keyword(s):  
Freezing Point ◽  
Younger Dryas ◽  
Northern Italy ◽  
Ice Age ◽  
Thermal Modelling ◽  
European Alps ◽  
Shallow Subsurface ◽  
Geomorphic Features ◽  
The Alps ◽  
Glacier Advance

Abstract. In the European Alps, the Younger Dryas (YD) was characterised by the last major glacier advance, with equilibrium line altitudes being ∼ 220 to 290 m lower than during the Little Ice Age, and also by the development of rock glaciers. Dating of these geomorphic features, however, is associated with substantial uncertainties, leading to considerable ambiguities regarding the internal structure of this stadial, which is the most intensively studied one of the last glacial period. Here, we provide robust physical evidence based on 230Th-dated cryogenic cave carbonates (CCCs) from a cave located at 2274 m a.s.l. in the Dolomites of northern Italy coupled with thermal modelling, indicating that early YD winters were only moderately cold in this part of the Alps. More precisely, we find that the mean annual air temperature dropped ≤ 3 ∘C at the Allerød–YD transition. Our data suggest that autumns and early winters in the early part of the YD were relatively snow-rich, resulting in stable winter snow cover. The latter insulated the shallow subsurface in winter and allowed the cave interior to remain close to the freezing point (0 ∘C) year-round, promoting CCC formation. The main phase of CCC precipitation at ∼ 12.2 ka coincided with the mid-YD transition recorded in other archives across Europe. Based on thermal modelling we propose that CCC formation at ∼ 12.2 ka was most likely associated with a slight warming of approximately +1 ∘C in conjunction with drier autumns and early winters in the second half of the YD. These changes triggered CCC formation in this Alpine cave as well as ice glacier retreat and rock glacier expansion across the Alps.

Cryogenic cave carbonates in the Dolomites (Northern Italy): insights into Younger Dryas cooling and seasonal precipitation

2021 ◽  
Author(s):  
Gabriella Koltai ◽  
Christoph Spötl ◽  
Alexander H. Jarosch ◽  
Hai Cheng
Keyword(s):  
Snow Cover ◽  
Freezing Point ◽  
Younger Dryas ◽  
First Record ◽  
Southern Alps ◽  
Ice Age ◽  
Thermal Modelling ◽  
European Alps ◽  
Shallow Subsurface ◽  
Glacier Advance

<p>In the European Alps, the Younger Dryas (YD) was characterized by the last major glacier advance with equilibrium line altitudes being ~220 to 290 m lower than during the Little Ice Age and also by the development of rock glaciers. Dating of these geomorphic features, however, is associated with substantial uncertainties leading to considerable ambiguities on the internal structure of this stadial, the most intensively studied one of the last glacial period.</p><p>Our study utilizes a novel paleoclimate archive, coarse crystalline cryogenic cave carbonates (hereafter CCC), that allows to precisely constrain when ~ 0°C conditions prevailed in the shallow subsurface in the past, often related to permafrost thawing events.</p><p>Here we presents the first record of CCC from the Dolomites (Southern Alps). In contrast to many studies from Central European caves these speleothems formed not during a major climate warming but within a prominent stadial. <sup>230</sup>Th-dating of the CCC indicates sustained negative temperatures close to  ~0°C between ~12.6 and ~12.2 ka BP at about 50 m below the surface, initiating the slow freezing of dripwater-induced meltwater pockets in perennial cave ice. This in combination with thermal modelling argues for a cooling of ≤ 3°C at the Allerød-YD transition at this high-alpine site in the Southern Alps. Our data suggest that autumns and early winters in the early part of the YD were relatively snow-rich, resulting in a stable winter snow cover at this site. The snow cover insulated the subsurface and allowed the cave interior to remain close to the freezing point (0°C) year-round, promoting CCC formation.</p><p>The main phase of CCC precipitation at ~12.2 ka BP coincides with the mid-YD transition recorded in other archives across Europe. Based on thermal modelling we propose that CCC formation at ~12.2 ka BP was most likely associated with a slight warming of approximately +1°C in conjunction with drier autumns and early winters in the second half of the YD. These changes triggered CCC formation in this alpine cave as well as ice glacier retreat and rock glacier expansion in the Alps. Our study demonstrates that CCCs can provide quantitative constraints on paleotemperature and seasonally resolved precipitation changes.</p>

Changing winter conditions in the Alps during the Younger Dryas cold period

2020 ◽  
Author(s):  
Gabriella Koltai ◽  
Christoph Spötl ◽  
Hai Cheng
Keyword(s):  
Younger Dryas ◽  
Meridional Overturning Circulation ◽  
Cold Trap ◽  
Northern Spain ◽  
Winter Climate ◽  
Shallow Subsurface ◽  
The Alps ◽  
Glacier Advance ◽  
Extreme Seasonality ◽  
Perennial Ice

<p>The Younger Dryas (YD, GS-1) is the latest of the canonical millennial-scale stadials of the last glacial period. Proxy data from terrestrial archives point to a climate dominated by extreme seasonality and continentality across Europe. YD summers were characterised by large meridional temperature gradients and remained quite warm despite the prominent slowdown of the Atlantic Meridional Overturning Circulation. The few available winter proxy records point to cold and dry winters.</p><p>In the Alps, the YD was characterised by the last major glacier advance and the development of rock glaciers. Dating these cryogenic geomorphological features, however, is associated with substantial uncertainties. A new type of secondary carbonate archive (coarsely crystalline cryogenic cave carbonates, or CCC<sub>coarse</sub>) has received increasing attention as a promising quantitative cryogenic indicator for the shallow subsurface environment. CCC<sub>coarse</sub> are found in karst caves and their formation is directly linked to thawing of perennial cave ice and U-series disequilibrium methods allow to date these events at high precision.</p><p>CCC<sub>coarse</sub> formed during the YD were found in three caves covering an approximately 170 km-long SW-NE transect. The entrance of Cioccherloch cave is located at 2245 m in the Dolomites; Frauenofen opens in the Tennengebirge at 1635 m, while the third cave, Großes Almbergloch, is situated in Totes Gebirge at an elevation of 1475 m. The thermal regime in Cioccherloch reflects the ambient mean annual air temperature, while the cave microclimate of Frauenofen and Großes Almbergloch is partially influenced by cold air intrusions in winter.</p><p><sup>230</sup>Th dating of twenty-two CCC<sub>coarse</sub> samples demonstrates that perennial ice was present in these caves during the first part of the YD, and Großes Almbergloch, Cioccherloch and Frauenofen warmed to 0°C at 12.32 ±0.09, 12.20 ±0.09, and 12.01 ±0.04 ka BP (weighted means), respectively, initiating slow thawing of cave ice bodies. Due to the partial cold trap behaviour of Frauenofen and Großes Almbergloch, a delay in cave ice demise and thus CCC<sub>coarse </sub>formation is likely. This and the higher elevation could explain the centennial lag observed in CCC<sub>coarse </sub>deposition in Frauenofen compared to Großes Almbergloch.</p><p>The change in the thermal condition of these caves commencing at ~12.3 ±0.1 ka BP is attributed to a change in the winter climate in the Alps, from dry to snow-rich and/or from extremely cold to milder winters. A snowpack could effectively insulate the shallow subsurface from the YD winter coldness, allowing the subsurface to slowly warm. The timing of this warming of the subsurface coincides with the mid-YD transition recorded in other archives across Europe (e.g., Meerfelder Maar, central Germany; El Soplao cave, northern Spain) and corroborates the hypothesis of a northward movement of the Westerlies during the mid-YD, bringing warmer air and moisture to the Alps. Our study also demonstrates that the interpretation of CCC<sub>coarse</sub> data requires a sound understanding of the cave geometry and the resulting mode of air exchange, since both the onset of perennial ice build-up and the eventual thawing may lag the atmospheric forcing outside the cave.</p>

scholarly journals Millennial‐scale deglaciation across the European Alps at the transition between the Younger Dryas and the Early Holocene – evidence from a new cosmogenic nuclide chronology

Boreas ◽  
2021 ◽  
Author(s):  
Marie Protin ◽  
Irene Schimmelpfennig ◽  
Jean‐Louis Mugnier ◽  
Jean‐François Buoncristiani ◽  
Melaine Le Roy ◽  
...  
Keyword(s):  
Younger Dryas ◽  
Early Holocene ◽  
European Alps ◽  
Cosmogenic Nuclide ◽  
Millennial Scale

scholarly journals High‐resolution proglacial lake records of pre‐Little Ice Age glacier advance, northeast Greenland

Boreas ◽  
2018 ◽  
Vol 48 (3) ◽  
pp. 535-550 ◽  
Author(s):  
Kathryn Adamson ◽  
Timothy Lane ◽  
Matthew Carney ◽  
Thomas Bishop ◽  
Cathy Delaney
Keyword(s):  
High Resolution ◽  
Little Ice Age ◽  
Ice Age ◽  
Proglacial Lake ◽  
Glacier Advance

scholarly journals Neoglacial history of Robson Glacier, British Columbia

2017 ◽  
Vol 54 (11) ◽  
pp. 1153-1164 ◽  
Author(s):  
B.H. Luckman ◽  
M.H. Masiokas ◽  
K. Nicolussi
Keyword(s):  
British Columbia ◽  
Little Ice Age ◽  
Ice Age ◽  
Tree Line ◽  
Canadian Rockies ◽  
The Holocene ◽  
Forest Sites ◽  
History Of ◽  
Subfossil Wood ◽  
Glacier Advance

As glaciers in the Canadian Rockies recede, glacier forefields continue to yield subfossil wood from sites overridden by these glaciers during the Holocene. Robson Glacier in British Columbia formerly extended below tree line, and recession over the last century has progressively revealed a number of buried forest sites that are providing one of the more complete records of glacier history in the Canadian Rockies during the latter half of the Holocene. The glacier was advancing ca. 5.5 km upvalley of the Little Ice Age terminus ca. 5.26 cal ka BP, at sites ca. 2 km upvalley ca. 4.02 cal ka BP and ca. 3.55 cal ka BP, and 0.5–1 km upvalley between 1140 and 1350 A.D. There is also limited evidence based on detrital wood of an additional period of glacier advance ca. 3.24 cal ka BP. This record is more similar to glacier histories further west in British Columbia than elsewhere in the Rockies and provides the first evidence for a post-Hypsithermal glacier advance at ca. 5.26 cal ka BP in the Rockies. The utilization of the wiggle-matching approach using multiple 14C dates from sample locations determined by dendrochronological analyses enabled the recognition of 14C outliers and an increase in the precision and accuracy of the dating of glacier advances.

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 3D structural and thermal modelling of Mesozoic petroleum systems in the Po Valley Basin, northern Italy

2017 ◽  
Vol 24 (2) ◽  
pp. 172-196 ◽  
Author(s):  
Claudio Turrini ◽  
Barbara Bosica ◽  
Paul Ryan ◽  
Peter Shiner ◽  
Olivier Lacombe ◽  
...  
Keyword(s):  
Northern Italy ◽  
Thermal Modelling ◽  
Petroleum Systems ◽  
Po Valley

Holocene and latest Pleistocene fluctuations of Stutfield Glacier, Canadian Rockies

2001 ◽  
Vol 38 (8) ◽  
pp. 1141-1155 ◽  
Author(s):  
G D Osborn ◽  
B J Robinson ◽  
B H Luckman
Keyword(s):  
19Th Century ◽  
18Th Century ◽  
Late Glacial ◽  
Ice Age ◽  
Late 19Th Century ◽  
Canadian Rockies ◽  
The Holocene ◽  
The North ◽  
History Of ◽  
Glacier Advance

The Holocene and late glacial history of fluctuations of Stutfield Glacier are reconstructed using moraine stratigraphy, tephrochronology, and dendroglaciology. Stratigraphic sections in the lateral moraines contain tills from at least three glacier advances separated by volcanic tephras and paleosols. The oldest, pre-Mazama till is correlated with the Crowfoot Advance (dated elsewhere to be Younger Dryas equivalent). A Neoglacial till is found between the Mazama tephra and a paleosol developed on the Bridge River tephra. A log dating 2400 BP from the upper part of this till indicates that this glacier advance, correlated with the Peyto Advance, culminated shortly before deposition of the Bridge River tephra. Radiocarbon and tree-ring dates from overridden trees exposed in moraine sections indicate that the initial Cavell (Little Ice Age (LIA)) Advance overrode this paleosol and trees after A.D. 1271. Three subsequent phases of the Cavell Advance were dated by dendrochronology. The maximum glacier extent occurred in the mid-18th century, predating 1743 on the southern lateral, although ice still occupied and tilted a tree on the north lateral in 1758. Subsequent glacier advances occurred ca. 1800–1816 and in the late 19th century. The relative extent of the LIA advances at Stutfield differs from that of other major eastward flowing outlets of the Columbia Icefield, which have maxima in the mid–late 19th century. This is the first study from the Canadian Rockies to demonstrate that the large, morphologically simple, lateral moraines defining the LIA glacier limits are actually composite features, built up progressively (but discontinuously) over the Holocene and contain evidence of multiple Holocene- and Crowfoot-age glacier advances.

scholarly journals Temperature and mineral dust variability recorded in two low-accumulation Alpine ice cores over the last millennium

2018 ◽  
Vol 14 (1) ◽  
pp. 21-37 ◽  
Author(s):  
Pascal Bohleber ◽  
Tobias Erhardt ◽  
Nicole Spaulding ◽  
Helene Hoffmann ◽  
Hubertus Fischer ◽  
...  
Keyword(s):  
Time Series ◽  
Mineral Dust ◽  
Ice Core ◽  
Ice Cores ◽  
Temperature Reconstruction ◽  
Relative Increase ◽  
Ice Age ◽  
European Alps ◽  
Stable Water Isotopes ◽  
Annual Layer

Abstract. Among ice core drilling sites in the European Alps, Colle Gnifetti (CG) is the only non-temperate glacier to offer climate records dating back at least 1000 years. This unique long-term archive is the result of an exceptionally low net accumulation driven by wind erosion and rapid annual layer thinning. However, the full exploitation of the CG time series has been hampered by considerable dating uncertainties and the seasonal summer bias in snow preservation. Using a new core drilled in 2013 we extend annual layer counting, for the first time at CG, over the last 1000 years and add additional constraints to the resulting age scale from radiocarbon dating. Based on this improved age scale, and using a multi-core approach with a neighbouring ice core, we explore the time series of stable water isotopes and the mineral dust proxies Ca2+ and insoluble particles. Also in our latest ice core we face the already known limitation to the quantitative use of the stable isotope variability based on a high and potentially non-stationary isotope/temperature sensitivity at CG. Decadal trends in Ca2+ reveal substantial agreement with instrumental temperature and are explored here as a potential site-specific supplement to the isotope-based temperature reconstruction. The observed coupling between temperature and Ca2+ trends likely results from snow preservation effects and the advection of dust-rich air masses coinciding with warm temperatures. We find that if calibrated against instrumental data, the Ca2+-based temperature reconstruction is in robust agreement with the latest proxy-based summer temperature reconstruction, including a “Little Ice Age” cold period as well as a medieval climate anomaly. Part of the medieval climate period around AD 1100–1200 clearly stands out through an increased occurrence of dust events, potentially resulting from a relative increase in meridional flow and/or dry conditions over the Mediterranean.

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