Alaska Glaciers - key indicator of climate change

Discussion in 'Environment' started by Saigon, May 12, 2012.

  1. Saigon
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    Saigon Gold Member

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    This came up on another thread, and I mentioned that I would present some research that I found very compelling...

    There are a few things I admit about this guy -
    1) He combines hard core field work he does himself alongside models and satellite work
    2) He is very quick to point out faults or potential problems with his methodology
    3) He doesn't make wild claims, and sticks to his area of speciality
    4) His work is ongoing, and sits alongside similar studies done by other researchers in other parts of the world. One of his colleagues recently published a work which concluded that 99% of Alaska's glaciers are retreating.

    Anthony Arendt has a PhD in geophysics and is an assistant research professor at the University of Fairbanks Alaska, and has worked with glaciers for many years now. He has been involved in a cluster of inter-related studies on various aspects of the glaciers.

    His research covers:
    - assessing contribution of glaciers and ice sheets to rising sea level
    - modeling glacier response to climate change
    - downscaling remote sensing data for hydrological modeling
    - validation of high-resolution satellite gravimetry (GRACE) data
    - development of aircraft and satellite laser altimetry mass balance methods

    Here is an overview, some findings, and then links to details:

    Overview:

    "We have used satellites to measure the mass changes of all of Alaska's glaciers, but there are also many glaciers that need to be measured in the field," Arendt said. "We need these field observations to better understand the processes that are controlling glacier changes."

    Glacial patterns are difficult to predict -- even for current computer models. Alaska glaciers often behave independently of one another. They retreat and surge, and are subject to volcanic and oceanic influences, in addition to changes in precipitation and warming temperatures. Data collected in the field will help refine existing models, so that a more accurate picture of changing sea level can be drawn.

    "Alaska glaciers have been losing mass more rapidly since the mid-1990s than they were several decades earlier," Arendt states in the article. "Understanding whether this trend continues will require an integration of observations across disciplines, as well as the development of robust glacier simulation models."

    Assessing the influence of Alaska glaciers is slippery work

    Methodology:

    Anthony Arendt, a graduate student in geophysics, and his supervisor Keith Echelmeyer, a professor of geology and geophysics, documented glacial elevations by flying a small plane over the ice rivers and using laser instruments to measure the surface below them. Arendt compared the data with the elevations recorded on topographical maps made in the 1950s by the U.S. Geological Survey.

    On 67 glaciers ranging from the western Alaska Range to Southeast Alaska, the average rate of thinning was almost a half-meter, or 20 inches, each year from the 1950s to the mid-1990s. On 27 of the glaciers, Arendt also calculated ice losses for just the last half of the 1990s, the time when the project was being conducted. There, he found average annual ice thinning of about one meter, or nearly 40 inches.

    Extrapolating from the data on the 67 glaciers to all of Alaska's glaciers, Arendt and the other researchers figured the total loss at 12 cubic miles of water-equivalent ice annually since the mid-1950s, with an error of plus or minus 1.67 cubic miles. From the mid-1990s through 2001, the glaciers lost 22 cubic miles annually, plus or minus 6.7 cubic miles.

    Arendt said there are some obvious limitations to their method that introduce errors into the ice-loss estimates, which required the inclusion of plus-or-minus qualifications on their figures. The largest error probably comes from the old maps.

    "The maps were made from aerial photographs and some of them have poor geodetic controls and some of them also have poor accuracy especially at the higher elevations where there is a lot of snow cover," Arendt told the Fairbanks Daily News-Miner.

    Glaciers shrink far faster in the last decade | Juneau Empire - Alaska's Capital City Online Newspaper

    Conclusions:

    We have used airborne laser altimetry to estimate volume changes of 67 glaciers in Alaska from the mid-1950s to the mid-1990s. The average rate of thickness change of these glaciers was -0.52 m/year. Extrapolation to all glaciers in Alaska yields an estimated total annual volume change of -52 +/- 15 km3/year (water equivalent), equivalent to a rise in sea level (SLE) of 0.14 +/- 0.04 mm/year. Repeat measurements of 28 glaciers from the mid-1990s to 2000-2001 suggest an increased average rate of thinning, -1.8 m/year. This leads to an extrapolated annual volume loss from Alaska glaciers equal to -96 +/- 35 km3/year, or 0.27 +/- 0.10 mm/year SLE, during the past decade. These recent losses are nearly double the estimated annual loss from the entire Greenland Ice Sheet during the same time period and are much higher than previously published loss estimates for Alaska glaciers. They form the largest glaciological contribution to rising sea level yet measured.

    Anthony A Arendt | ResearchGate

    What's Happening to Alaska's Glaciers? | OurAmazingPlanet.com

    Anthony Arendt
     
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  2. skookerasbil
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    skookerasbil Gold Member

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    Last edited: May 12, 2012
  3. Saigon
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    Saigon Gold Member

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  4. daveman
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    daveman Diamond Member

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    This leads to an extrapolated annual volume loss from Alaska glaciers equal to -96 +/- 35 km3/year, or 0.27 +/- 0.10 mm/year SLE, during the past decade.​

    And in a hundred years, that leads to a sea level increase of one inch.

    ZOMGWTFBBQ! We're all gonna die!! :ack-1:
     
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  5. skookerasbil
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    skookerasbil Gold Member

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    Nah........part of the information provided in my link above speaks to all the science that is publicized that matches the agenda of the bomb throwers. Glaciers are always retreating in some places..........expanding in others. My role in this forum is to expose the hoax for people who wander in here looking to get the whole story,..........not just the crap conveyed by the k00k bomb throwers

    But really, at the end of the day...........in 2012, the only people who find glacier stories intersting are the OCD internet nutters. Nobody cares which is evidenced by the fact that in the past few years, caps on greenhouse gasses are a dead issue in Congress. Even the most k00k district reps dont bother to bring shit to the floor anymore because its laughable.........which means, the science isnt mattering. And in the coming decades, America is going to be fracking our asses off FTW!!! Why? Because most Americans want and need cheap energy.


    By the way............the "gossip" is winning!!!:fu:
     
    Last edited: May 12, 2012
  6. Saigon
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    Saigon Gold Member

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    Daveman -

    You've actually highlighted one reason I find this research interesting - precisely because is NOT saying that we are all going to die. What he is saying is that 99% of glaciers are in retreat, and that this will have a minor effect globally on sea levels.

    What I think a sensible person might take from that, is that there are glaciers in Nepal, Argentina, Switzerland, Greenland and Canada as well - and if they are all melting at a similar rate to those in Alaska, and combined with Arctic and Antarctic melt, than we could see a rise in sea levels that might make life in cities like LA, New York, Miami, Hong Kong, Amsterdam, London, Cairo, Calcutta, Mumbai, Sydney, San Diego, San Francisco, Bangkok, Jakarta and Manila a little difficult.

    Would you consider that worth studying?
     
  7. Saigon
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    Saigon Gold Member

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    Then please present evidence accordingly.

    And again - peer-reviewed, academic research conducted by experts in this field.

    And I don't mean finding one glacier expanding in a field of 100 declining glaciers - I mean an entire glacier field which shows a pattern of growth.
     
  8. Old Rocks
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    Old Rocks Diamond Member

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  9. Saigon
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    Saigon Gold Member

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    It seems so - from what I've read well over 90% of glaciers worldwide are reateating, and only 1 - 2% advancing.

    I've heard (what seem to me like) fairly absurd theories about how much sea levels will rise as a result, but it seems to me that even a rise of 1 - 2 metres could have a profound impact in a lot of cities. How much of a rise in sea level would it take to start seeping into foundations of buildings in Manhatten?
     
  10. daveman
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    daveman Diamond Member

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    Certainly. Glaciers have always advanced and retreated. Climate has always changed, and always will.

    I was mocking the AGW cult. And here's a question: What happened to sea levels during the MWP? Were the coasts inundated?
     

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