Canadian Glaciers

Discussion in 'Environment' started by Old Rocks, Dec 25, 2012.

  1. Old Rocks
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    Old Rocks Diamond Member

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    TC - Abstract - Area change of glaciers in the Canadian Rocky Mountains, 1919 to 2006

    Area change of glaciers in the Canadian Rocky Mountains, 1919 to 2006

    C. Tennant1, B. Menounos1,2, R. Wheate1,2, and J. J. Clague3
    1Geography Program, University of Northern British Columbia, Prince George, British Columbia, V2N 4Z9, Canada
    2Natural Resources and Environmental Studies Institute, University of Northern British Columbia, Prince George, British Columbia, V2N 4Z9, Canada
    3Department of Earth Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada

    Abstract. Glaciers in the Canadian Rocky Mountains constitute an important freshwater resource. To enhance our understanding of the influence climate and local topography have on glacier area, large numbers of glaciers of different sizes and attributes need to be monitored over periods of many decades. We used Interprovincial Boundary Commission Survey (IBCS) maps of the Alberta–British Columbia (BC) border (1903–1924), BC Terrain Resource Information Management (TRIM) data (1982–1987), and Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) imagery (2000–2002 and 2006) to document planimetric changes in glacier cover in the central and southern Canadian Rocky Mountains between 1919 and 2006. Over this period, glacier cover in the study area decreased by 590 ± 70 km2 (40 ± 5%), 17 of 523 glaciers disappeared and 124 glaciers fragmented into multiple ice masses. Glaciers smaller than 1.0 km2 experienced the greatest relative area loss (64 ± 8%), and relative area loss is more variable with small glaciers, suggesting that the local topographic setting controls the response of these glaciers to climate change. Small glaciers with low slopes, low mean/median elevations, south to west aspects, and high insolation experienced the largest reduction in area. Similar rates of area change characterize the periods 1919–1985 and 1985–2001; −6.3 ± 0.6 km2 yr−1 (−0.4 ± 0.1% yr−1) and −5.0 ± 0.5 km2 yr−1 (−0.5 ± 0.1% yr−1), respectively. The rate of area loss, however, increased over the period 2001–2006; −19.3 ± 2.4 km2 yr−1 (−2.0 ± 0.2% yr−1). Applying size class-specific scaling factors, we estimate a total reduction in glacier cover in the central and southern Canadian Rocky Mountains for the period 1919–2006 of 750 km2 (30%).
     
  2. CrusaderFrank
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    CrusaderFrank Diamond Member

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    Yawn.
     
  3. CrusaderFrank
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    CrusaderFrank Diamond Member

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    [​IMG]

    Glacier have been melting for the past 14,000 years.
     
  4. Toro
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    Toro Diamond Member

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    I stay away from these threads generally because I have no opinion about global warming but the Arctic ice caps are melting.

    We have a company that makes the technology which satellites use to precisely measure the earth for all sorts of reasons, and they say there is zero doubt that the Arctic ice caps are getting smaller.

    Interestingly, according to this firm, the Antarctic glaciers are not.
     
  5. Mr. H.
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    Mr. H. Diamond Member

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    I wonder how much ice actually melts, and how much sublimates?
    There's a difference y'know.
     
  6. Old Rocks
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    Old Rocks Diamond Member

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    Good point. The ice in the continental glaciers, other than Antarctica, are melting. In Antarctica, surface loss is mostly sublimation. Most of the Antarctic loss is from glaciers pushing out into the sea, in the areas where the sea shelves have broken up. The glaciers there have not gotten smaller, as on the other continents, but have started moving toward the sea faster than in the little time we have observed that continent.
     
  7. westwall
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    westwall USMB Mod Staff Member Gold Supporting Member Supporting Member

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    Don't take this wrong, but, so what? There was more glacial loss before 1900 than there has been after 1900...and by a lot. Myopic studies that don't look at historical trends are meaningless.
     
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  8. Old Rocks
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    Old Rocks Diamond Member

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    That is your claim. I note no confirming link to a scientific source.
     
  9. CrusaderFrank
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    CrusaderFrank Diamond Member

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    Is this another "Oh no! It's the Great Glacier Eating CO2 Spaghetti Monster, Charlie Brown!!" Thread?
     
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  10. Trakar
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    Trakar VIP Member

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    Well, the antarctic glaciers don't visibly "shrink" as much under satellite observation, nor are they under as much visual satellite scrutiny. The mass of the Antarctic ice caps, however, is decreasing at an accelerating rate and a major contributor increasing sea-level rise.


    "A Reconciled Estimate of Ice-Sheet Mass Balance" - http://xa.yimg.com/kq/groups/18383638/836588054/name/Science-2012-Shepherd-1183-9.pdf

    - abstract
    "We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using
    common geographical regions, time intervals, and models of surface mass balance and
    glacial isostatic adjustment to estimate the mass balance of Earth​
    [FONT=AdvTTdeec4450+20][FONT=AdvTTdeec4450+20]’
    [/FONT]s polar ice sheets. We find that
    there is good agreement between different satellite methods
    [FONT=AdvTTdeec4450+20][FONT=AdvTTdeec4450+20]—[/FONT][/FONT]especially in Greenland and
    West Antarctica
    [FONT=AdvTTdeec4450+20][FONT=AdvTTdeec4450+20]—[/FONT][/FONT]and that combining satellite data sets leads to greater certainty. Between 1992
    and 2011, the ice sheets of Greenland, East Antarctica, West Antarctica, and the Antarctic
    Peninsula changed in mass by
    [FONT=AdvTTdeec4450+20][FONT=AdvTTdeec4450+20]–[/FONT][/FONT]142 T 49, +14 T 43, [FONT=AdvTTdeec4450+20][FONT=AdvTTdeec4450+20]–[/FONT][/FONT]65 T 26, and [FONT=AdvTTdeec4450+20][FONT=AdvTTdeec4450+20]–[/FONT][/FONT]20 T 14 gigatonnes year[FONT=AdvTTdeec4450+22][FONT=AdvTTdeec4450+22]−[/FONT][/FONT]1,
    respectively. Since 1992, the polar ice sheets have contributed, on average, 0.59
    T 0.20 millimeter

    year
    [FONT=AdvTTdeec4450+22][FONT=AdvTTdeec4450+22]−[/FONT][/FONT]1 to the rate of global sea-level rise."
    [/FONT]
     

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