Changes in Canadian Arctic Ice Shelf Extent Since 1906

AbstractNumerous studies of the ice caps in Greenland and Antarctica have observed accumulations of transuranic radionuclides and fission products from nuclear weapons testing, particularly during the period 1945–75. Recently, the concentrations of radionuclides in the annually deposited surface layers of Agassiz Ice Cap, Ellesmere Island, Canadian Arctic, from 1945 to the present have been measured and have demonstrated a continuous record of deposition of 137Cs and 239,240Pu in ice and snow. In this study, 3He-ingrowth mass spectrometry has been used to measure the low levels of tritium (3H) in some of these samples. Pre-nuclear-bomb tritium levels in ice-core samples were approximately 12 TU in high-latitude meteoric waters and 3–9 TU in mid-latitude meteoric waters. Comparisons of 3H levels and 3H/137Cs + 239,240Pu ratios, which were quite low during the earliest fission-bomb detonations (1946–51) and substantially higher during thermonuclear hydrogen-fusion bomb testing (1952–64), provide a clear indication of the type of nuclear device detonated. This finding accords with the results from other ice-core studies of the distribution of anthropogenic radionuclides from bomb fallout.

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The role of an Arctic ice shelf in the climate of the MIS 6 glacial maximum (140 ka)

Quaternary Science Reviews ◽

10.1016/j.quascirev.2010.06.023 ◽

2010 ◽

Vol 29 (25-26) ◽

pp. 3590-3597 ◽

Cited By ~ 5

Author(s):

F. Colleoni ◽

G. Krinner ◽

M. Jakobsson

Keyword(s):

Glacial Maximum ◽

Ice Shelf ◽

Arctic Ice

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Arctic Ice Island and Ice Shelf Studies: Part II

ARCTIC ◽

10.14430/arctic3687 ◽

1960 ◽

Vol 13 (1) ◽

Cited By ~ 53

Author(s):

A.P. Crary

Keyword(s):

Ice Shelf ◽

Arctic Ice

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Recent melt rates of Canadian arctic ice caps are the highest in four millennia

Global and Planetary Change ◽

10.1016/j.gloplacha.2011.06.005 ◽

2012 ◽

Vol 84-85 ◽

pp. 3-7 ◽

Cited By ~ 67

Author(s):

David Fisher ◽

James Zheng ◽

David Burgess ◽

Christian Zdanowicz ◽

Christophe Kinnard ◽

...

Keyword(s):

Canadian Arctic ◽

Ice Caps ◽

Arctic Ice

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Dynamic response of an Arctic epishelf lake to seasonal and long-term forcing: implications for ice shelf thickness

10.5194/tc-2017-19 ◽

2017 ◽

Cited By ~ 1

Author(s):

Andrew K. Hamilton ◽

Bernard E. Laval ◽

Derek R. Mueller ◽

Warwick F. Vincent ◽

Luke Copland

Keyword(s):

Seasonal Variation ◽

Canadian Arctic ◽

The Arctic ◽

Ice Shelf ◽

Ice Shelves ◽

Air Temperatures ◽

Long Term Changes ◽

Episodic Mixing ◽

Outflow Pathway

Abstract. Changes in the depth of the freshwater-seawater interface in epishelf lakes have been used to infer long-term changes in the thickness of ice shelves, however, little is known about the dynamics of epishelf lakes and what other factors may influence their depth. Continuous observations collected between 2011 and 2014 in the Milne Fiord epishelf lake, in the Canadian Arctic, showed that the depth of the halocline varied seasonally by up to 3.3 m, which was comparable to interannual variability. The seasonal depth variation was controlled by the magnitude of surface meltwater inflow and the hydraulics of the inferred outflow pathway, a narrow basal channel in the Milne Ice Shelf. When seasonal variation and an episodic mixing of the halocline were accounted for, long-term records of depth indicated there was no significant change in thickness of ice along the basal channel from 1983 to 2004, followed by a period of steady thinning at 0.50 m a-1 between 2004 and 2011. Rapid thinning at 1.15 m a-1 then occurred from 2011 to 2014, corresponded to a period of warming regional air temperatures. Continued warming is expected to lead to the breakup of the ice shelf and the imminent loss of the last known epishelf lake in the Arctic.

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Remote Sensing of Sea-Ice Growth and Melt-Pool Evolution, Milne Ice Shelf, Ellesmere Island, Canada

Annals of Glaciology ◽

10.1017/s0260305500000525 ◽

1987 ◽

Vol 9 ◽

pp. 145-150 ◽

Cited By ~ 2

Author(s):

Martin O. Jeffries ◽

William M. Sackinger ◽

Harold V. Serson

Keyword(s):

Sea Ice ◽

Drainage System ◽

Outer Part ◽

The Arctic ◽

Ice Shelf ◽

Ice Shelves ◽

Ice Growth ◽

Radar Images ◽

Melt Pool ◽

Arctic Ice

Periodically since 1950, air photographs and SLAR images have been taken of the Arctic ice shelves. The study of air photographs and SLAR images of the outer part of Milne Ice Shelf had three aims: (1) to map losses and ice re-growth at the shelf front, (2) to map the evolution of melt pools on shelf ice and multi-year land-fast sea ice, and (3) to assess the usefulness of air photographs and SLAR for these purposes. For mapping of ice calvings and subsequent sea-ice growth, both air photographs and radar images have been used sucessfully. However, air photographs are better than radar for mapping ice-surface features. The ridge-and-trough systems that characterize the surface of the ice shelf and old sea ice are clearly visible on each type of imagery but, because of their larger scale, air photographs proved to be most useful for a study of melt-pool evolution. The orientation of the melt pools is parallel to the prevailing winds which drive water along the troughs. The drainage system evolves by a process of elongation and coalesence.

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