Little Ice Age and neoglacial landforms at the Inland Ice margin, Isunguata Sermia, Kangerlussuaq, west Greenland

Boreas ◽  
2007 ◽  
Vol 36 (4) ◽  
pp. 341-351 ◽  
Author(s):  
Steven L. Forman ◽  
Liliana Marín ◽  
Cornelis Van Der Veen ◽  
Catherine Tremper ◽  
Bea Csatho
2008 ◽  
Vol 54 (184) ◽  
pp. 131-144 ◽  
Author(s):  
Bea Csatho ◽  
Toni Schenk ◽  
C.J. Van Der Veen ◽  
William B. Krabill

AbstractRapid thinning and velocity increase on major Greenland outlet glaciers during the last two decades may indicate that these glaciers became unstable as a consequence of the Jakobshavn effect (Hughes, 1986), with terminus retreat leading to increased discharge from the interior and consequent further thinning and retreat. To assess whether recent trends deviate from longer-term behavior, we measured glacier surface elevations and terminus positions for Jakobshavn Isbræ, West Greenland, using historical photographs acquired in 1944, 1953, 1959, 1964 and 1985. These results were combined with data from historical records, aerial photographs, ground surveys, airborne laser altimetry and field mapping of lateral moraines and trimlines, to reconstruct the history of changes since the Little Ice Age (LIA). We identified three periods of rapid thinning since the LIA: 1902–13, 1930–59 and 1999–present. During the first half of the 20th century, the calving front appears to have been grounded and it started to float during the late 1940s. The south and north tributaries exhibit different behavior. For example, the north tributary was thinning between 1959 and 1985 during a period when the calving front was stationary and the south tributary was in balance. The record of intermittent thinning, combined with changes in ice-marginal extent and position of the calving front, together with changes in velocity, imply that the behavior of the lower parts of this glacier represents a complex ice-dynamical response to local climate forcings and interactions with drainage from the interior.


2012 ◽  
Vol 27 ◽  
pp. 1-68 ◽  
Author(s):  
Anker Weidick ◽  
Ole Bennike ◽  
Michele Citterio ◽  
Niels Nørgaard-Pedersen

The Nuup Kangerlua region in southern West Greenland became deglaciated in the early Holocene and by the mid-Holocene, the margin of the Inland Ice was located east of its present position. Discussion of late Holocene changes in the frontal positions of outlets relies on descriptions, paintings, photographs, maps, data from investigations of Norse ruins, aerial photographs and satellite images. The Kangiata Nunaata Sermia glacier system has receded over 20 km during the last two centuries, indicating a marked response to climatic fluctuations during and since the Little Ice Age (LIA). A large advance between 1700 and 1800 was followed by rapid recession in the first half of the 1800s. Limited data from c. 1850–1920 indicate that although the long-term position of the glacier front remained c. 10–12 km behind the LIA maximum, the late 1800s and the early 1900s may have seen a recession followed by an advance that resulted in a pronounced moraine system. The ice-dammed lake Isvand formed during the LIA maximum when meltwater from the western side of Kangiata Nunaata Sermia drained to the Ameralla fjord in the west. This is in contrast to the drainage pattern before the 1700s, when water probably drained to Kangersuneq in the north. Thinning of Kangiata Nunaata Sermia resulted in total drainage of Isvand between 2000 and 2010 and the discharge of water through Austmannadalen has now returned to the same level as that in medieval times. Other outlets in the region, such as Akullersuup Sermia and Qamanaarsuup Sermia have varied in phase with Kangiata Nunaata Sermia, but with amplitudes of only a few kilometres. In contrast, Narsap Sermia has been nearly stationary and Kangilinnguata Sermia may have advanced until the middle of the 1900s. Lowland marine outlets in south-western Greenland were characterised by large amplitude changes during the Neoglacial. Extreme examples, in addition to Kangiata Nunaata Sermia, are Eqalorutsit Killiit Sermiat at the head of Nordre Sermilik fjord in southern Greenland and Jakobshavn Isbræ in Disko Bugt, central West Greenland. The Neoglacial advances appear to have occurred at different times, although this may in part reflect the limited information about fluctuations prior to the 1930s. The differences could also reflect variations in mass balance of different sectors of the ice sheet, different subglacial dynamics or topographical factors. The lowland areas are separated by uplands and highlands that extend below the marginal part of the Inland Ice; in such areas, the outlets have been advancing almost up to the present, so that the position of the glacier front around AD 2000 broadly coincides with the LIA maximum. Charting the fluctuations of the outlets thus illustrates the large variability of the glaciers' response to changing climate but it is notable that the number of advancing outlets has decreased markedly in recent years.


1991 ◽  
Vol 35 (1) ◽  
pp. 25-40 ◽  
Author(s):  
Atle Neshe ◽  
Svein Olaf Dahl

AbstractA 1-m-deep gully section 460 m beyond the maximum Little Ice Age marginal moraines of Blåisen, Hardangerjøkulen, central southern Norway, revealed alternations of minerogenic and organic sediments. The geographical/geological settings of the dated section provides a unique on/off signal of Holocene glacier fluctuations of Blåisen. Lithostratigraphy, sediment characteristics, and radiocarbon dates from the study section indicate one period of glacier (re)advance between the late Preboreal deglaciation of the inland ice sheet and 8660 ± 100 yr B.P. A grey sand layer 56–57 cm below the surface is interpreted to be of fluvial/colluvial origin and is radiocarbon dated to about 7700 yr B.P. At 48 cm below the surface, a bluish-grey sand/silt layer is radiocarbon dated to 7590 ± 12 yr B.P. (6560–6240 B.C.) and interpreted to be glaciofluvial origin. A minor glacier oscillation postdates 1130 ± 70 yr B.P. (810–990 A.D.). The Medieval/Little Ice Age glacier advance of Blåisen beyond its modern extent occurred after 1040 ± 60 yr B.P. (960–1030 A.D.). Calculations of the modern and Little Ice Age equilibrium-line altitudes (ELAs) on Hardangerjøkulen suggest an ELA depression of ca. 130 m during the Little Ice Age maximum.


Author(s):  
W.P. De Lange

The Greenhouse Effect acts to slow the escape of infrared radiation to space, and hence warms the atmosphere. The oceans derive almost all of their thermal energy from the sun, and none from infrared radiation in the atmosphere. The thermal energy stored by the oceans is transported globally and released after a range of different time periods. The release of thermal energy from the oceans modifies the behaviour of atmospheric circulation, and hence varies climate. Based on ocean behaviour, New Zealand can expect weather patterns similar to those from 1890-1922 and another Little Ice Age may develop this century.


2013 ◽  
Vol 6 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Anastasia Gornostayeva ◽  
◽  
Dmitry Demezhko ◽  
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Keyword(s):  

2020 ◽  
Vol 42 (1) ◽  
pp. 4-12
Author(s):  
Valeriy Fedorov ◽  
Denis Frolov

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