Younger dryas and holocene glacier fluctuations and equilibrium-line altitude variations in the Jostedalsbre region, western Norway

1992 ◽  
Vol 6 (3-4) ◽  
pp. 221-227 ◽  
Author(s):  
Atle Nesje
Keyword(s):  
Younger Dryas ◽  
Equilibrium Line ◽  
Equilibrium Line Altitude ◽  
Glacier Fluctuations ◽  
Western Norway

scholarly journals Equilibrium-line altitudes and rock glaciers during the Younger Dryas cooling event, Ferwall group, western Tyrol, Austria

1999 ◽  
Vol 28 ◽  
pp. 141-145 ◽  
Author(s):  
Rudolf Sailer ◽  
Hanns Kerschner
Keyword(s):  
Little Ice Age ◽  
Younger Dryas ◽  
Late Glacial ◽  
Ice Age ◽  
Equilibrium Line ◽  
Rock Glacier ◽  
Equilibrium Line Altitude ◽  
Discontinuous Permafrost ◽  
Rock Glaciers ◽  
Temperature Depression

AbstractThree cirques in the Ferwall group, western Tyrol, Austria, which are characterized by distinct Late-glacial moraines and rock glaciers, are discussed. The morphology of the moraines and the depression of the equilibrium-line altitude suggest they were deposited during the Egesen Stadial (Younger Dryas), which can be subdivided into three substages. Rock-glacier formation was initialized during or after the Egesen II substage. They became inactive at the Pleistocene—Holocene transition. ELA values are 290–320 m lower than the Little Ice Age ELA during the Egesen I substage, 190–230 m lower during the Egesen II substage and 120 —160 m lower during the Egesen III substage. The lowering of the rock-glacier belt (discontinuous permafrost) during and after the Egesen II substage is about 400 m, indicating a mean annual air-temperature depression in the order of 3 K. During the Egesen I (earlyYounger Dryas), the climate seems to have been rather cold and wet with precipitation similar to present-day values. During later phases (Egesen II and III), the climate remained cold and became increasingly drier. The rise of the ELA during the Egesen I—III substages seems to have been mainly caused by a decrease in precipitation.

Morphostratigraphic principles in glacier reconstruction -a perspective from the British Younger Dryas

2006 ◽  
Vol 30 (6) ◽  
pp. 719-736 ◽  
Author(s):  
Sven Lukas
Keyword(s):  
Numerical Models ◽  
Younger Dryas ◽  
Equilibrium Line ◽  
River Terrace ◽  
Equilibrium Line Altitude ◽  
Glacier Reconstruction ◽  
Sediment Cover ◽  
Input Variables ◽  
Raised Beaches ◽  
Numerical Dating

Glacier reconstruction enables the calculation of palaeoglaciological and palaeoclimatic variables such as the equilibrium-line altitude and palaeo-precipitation values. Such data are important for our understanding of past atmosphere-cryosphere interactions and as input variables to constrain numerical models effectively. Numerical dating is crucial to constrain the age of glacial events, but, due to absence of dateable material and/or contamination problems, ice masses can frequently be constrained satisfactorily only in a few locations. Thus, extrapolation and interpolation of geomorphological evidence is required to establish the extent of glaciers at a given time for the whole ice mass. Using examples from areas in Britain that were last covered by glaciers during the Younger Dryas, geomorphological approaches are reviewed and potential pitfalls highlighted. A multiproxy morphostratigraphic approach that utilizes clear landsystem contrasts inside and outside dated glacial limits is developed and tested in an area where numerical dates are sparse. Landform assemblages suitable in this respect are the type and frequency of moraines, river terrace sequences, glaciofluvial landforms, raised beaches, the upslope terminations of sediment cover (‘drift limits’), periglacial trimlines and periglacial features such as blockfields, solifluction lobes and thick talus accumulations. It is concluded that, if multiple lines of geomorphological evidence converge, these can be used to confine the extent of past glaciers in a given area and to guide dating programmes.

scholarly journals Glacier equilibrium line altitude variations during the “Little Ice Age” in the Mediterranean Andes (30◦–37◦ S)

2019 ◽  
Author(s):  
Álvaro González-Reyes ◽  
Claudio Bravo ◽  
Mathias Vuille ◽  
Martin Jacques-Coper ◽  
Maisa Rojas ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Pearson Correlation ◽  
Temporal Changes ◽  
Global Climate Models ◽  
Ice Age ◽  
Equilibrium Line ◽  
Equilibrium Line Altitude ◽  
Mountainous Regions ◽  
The Mean ◽  
The Mediterranean

Abstract. The "Little Ice Age" (LIA; 1500–1850 Common Era (CE)), has long been recognized as the last period when mountain glaciers in many regions of the Northern Hemisphere (NH) recorded extensive growth intervals in terms of their ice mass and frontal position. The knowledge about this relevant paleoclimatic interval is vast in mountainous regions such as the Alps and Rocky Mountains in North America. However, in extra-tropical Andean sub-regions such as the Mediterranean Andes of Chile and Argentina (MA; 30º–37º S), the LIA has been poorly documented. Paradoxically, the few climate reconstructions performed in the MA based on lake sediments and tree rings do not show clear evidence of a LIA climate anomaly as observed in the NH. In addition, recent studies have demonstrated temporal differences between mean air temperature variations across the last millennium between both hemispheres. This motivates our hypothesis that the LIA period was not associated with a significant climate perturbation in the MA region. Considering this background, we performed an experiment using daily climatic variables from three Global Climate Models (GCMs) to force a novel glaciological model. In this way, we simulated temporal variations of the glacier equilibrium-line altitude (ELA) to evaluate the glacier response during the period 1500–1848 CE. Overall, each GCM shows temporal changes in annual ELA, with anomalously low elevations during 1640–1670 and 1800–1848 CE. An interval with high ELA values was identified during 1550–1575 CE. The spectral properties of the mean annual ELA in each GCM present significant periodicities between 2–7 years, and also significant decadal to multi-decadal signals. In addition, significant and coherent cycles at interannual to multi-decadal scales were detected between modeled mean annual ELAs and the first EOF1 extracted from Sea Surface Temperature (SST) within the El Niño 3.4 of each GCM. Finally, significant Pearson correlation coefficients were obtained between the mean annual ELA and Pacific SST on interannual to multi-decadal timescales. According to our findings, we propose that Pacific SST variability was the main modulator of temporal changes of the ELA in the MA region of South America during 1500–1848 CE.

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