Recent Glacier Retreat Research Articles

Recent Glacier Retreat Exceeds Internal Variability

Glacier fluctuations exclusively due to internal variations in the climate system are simulated using downscaled integrations of the ECHAM4/OPYC coupled general circulation model (GCM). A process-based modeling approach using a mass balance model of intermediate complexity and a dynamic ice flow model considering simple shearing flow and sliding are applied. Multimillennia records of glacier length fluctuations for Nigardsbreen (Norway) and Rhonegletscher (Switzerland) are simulated using autoregressive processes determined by statistically downscaled GCM experiments. Return periods and probabilities of specific glacier length changes using GCM integrations excluding external forcings such as solar irradiation changes, volcanic, or anthropogenic effects are analyzed and compared to historical glacier length records. Preindustrial fluctuations of the glaciers as far as observed or reconstructed, including their advance during the ‘‘Little Ice Age,’’ can be explained by internal variability in the climate system as represented by a GCM. However, fluctuations comparable to the present-day glacier retreat exceed any variation simulated by the GCM control experiments and must be caused by external forcing, with anthropogenic forcing being a likely candidate.

Past and recent glacier fluctuations in Kanchenjunga Himal, Nepal

Kanchenjunga Himal, which lies in the easternmost part of the Nepal Himalaya, is a typical area under strong summer monsoon environment. Studies on glacial variations of Kanchenjunga Himal can reveal climate changes particularly monsoon fluctuations since the Last Glaciation and those in the recent time.
 The aerial photo interpretation and field observation identified changing valley morphology from an ambiguous U-shaped to a V-shaped along the Ghunsa Khola at an altitude of approximately 2.800 m. This clear morphological change may indicate the former maximum extent of the glaciers. Geographical positions of glacial landforms and relative dating data led to the classification of the glacial activities into at least five stages. From the younger lo older order, they are historical stage (around the early part of the Twentieth Century), the Little Ice Age, the Holocene, and the late and early substages of the Last Glaciation. The two substages could be correlated with the Last Glacial Maximum (LGM) and Marine Isotope Stage 3 or 4. The extent of the glaciers in the LGM was not generally so large as compared with that of the existing glaciers. Relatively small glacier expansion can probably suggest, weaker summer monsoon and less precipitation in the LGM period.
 A comparison of the 1992 glaciers with those of 1958 in the Ghunsa Khola drainage, the main drainage of Kanchenjunga Himal, revealed that out of examined 57 glaciers, 50% of them had retreated in the period from 1958 to 1992. Also, 38%of the glaciers were under stationary conditions, and 12% were advancing. Consequently, the general tendency should be regarded as "mostly retreating". The distribution and magnitude of the glacier variations suggest that general rising of air temperature possibly caused the recent glacier retreat, and that the stationary or advancing conditions were likely to be related to the local increase and variations of precipitation.

Paraglacial Slope Adjustment and Resedimentation Following Recent Glacier Retreat, Fabergstolsdalen, Norway

Withdrawal of glacier ice from upper Fabergstolsdalen after A.D. 1930 has exposed steep drift-covered slopes on the north side of the valley. Since 1943 these have experienced radical transformatio...

Variations of the Ice Margins in East Antarctica

Since THE last century, glaciers over most of the earth have been shrinking. A mass of evidence of his trend has been collected by Ahlmann in comprehensive survey of glacier variations,1 while other writers, too numerous to mention, have brought forward proof of recent glacier recessions in Europe, North and South America, Africa, Asia, New Zealand, and the Arctic regions. Since about 1940-50, however, there are signs that the recession has become less general in the Northern Hemisphere and there is some evidence that the temperature rise in the Arctic culminated about 1940.* Glacial recession has been widespread throughout the Arctic and Sub-arctic, and numerous examples have been reported from Alaska, Canada, Iceland, Jan Mayen, Spitsbergen, Franz Josef Land, Novaya Zemlya, Norway, and the outflow glaciers of the Greenland ice cap. It would seem reasonable, then, to consider the possibility of some corresponding process in Antarctica and, indeed, some reports 3 give the im? pression that ice recession was occurring in west Antarctica in 1940. Further reports of recent glacier retreat at Heard Island have been made by several members of the A.N.A.R.E. (Australian National Antarctic Research Expeditions). Against this, how? ever, Schytt4 was able to state that no appreciable thinning of the ice had occurred in Dronning Maud Land for many years prior to 1950. In these circumstances the writer, while working at Mawson with the A.N.A.R.E. during the International Geophysical Year, approached the question of ice margin variations in east Antarctica with an open mind. The studies in this field were divided into two broad categories: an attempt to show whether or not there had been fluctuations of the ice margins during the past century or so, and a search for evidence of changes on a larger time scale, i.e. post-Pleistocene variations. These will be considered in turn.