Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Glaciers that grew when temperature increased

  1. Sep 1, 2009 #1

    wolram

    User Avatar
    Gold Member

    http://www.sciencedaily.com/releases/2009/08/090827101207.htm

    I thought this was an interesting article,

    Ice when heated is supposede to melt That’s why a collection of glaciers in the Southeast Himalayas stymies those who know what they did 9,000 years ago. While most other Central Asian glaciers retreated under hotter summer temperatures, this group of glaciers advanced from one to six kilometers.
     
  2. jcsd
  3. Sep 1, 2009 #2

    Borek

    User Avatar

    Staff: Mentor

    It is an equilibrium between preicipitation, transport, and melting - melting increases with temperature, but that's only one of three elements involved.
     
  4. Sep 2, 2009 #3

    matthyaouw

    User Avatar
    Gold Member

    Like Borek says it's a complex thing with many factors. Rising global temperatures could cause more precipitation in certain areas. So more ice, more glaciers.
     
  5. Sep 2, 2009 #4
    Maybe it also works in the opposite direction: sinking temperatures could cause less precipitation in certain areas. So less ice, less glaciers.
     
  6. Sep 2, 2009 #5

    Borek

    User Avatar

    Staff: Mentor

    I would be surprised if there will be no such examples :smile:
     
  7. Sep 2, 2009 #6

    Xnn

    User Avatar

    There are areas of the world that are very cold and arid.
    If they were to warm and become more humid, then glaciers can grow better.

    I happen to live in an area that is generally cold enough during the winter for snow to fall. However, I've noticed that when its extremely cold, it's also very dry. So, in general, the largest snow falls occur during warming periods.

    Our local TV meterologist has also noticed this and plotted data showing that snow fall has increased over the last 30 year while winter temperatures have risen. So, as strange as it may seem, with global warming, we are receiving more snow (it is just wetter and melts faster).
     
  8. Sep 2, 2009 #7

    wolram

    User Avatar
    Gold Member

    I am sure you could give some evidence for this Andre.
     
  9. Sep 2, 2009 #8

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    We need to be careful about making claims of cause and effect without a supporting paper.
     
  10. Sep 2, 2009 #9
    Very well, let's have a look in the French Alps, the highest mountain, the Mont Blanc.

    The glacier monitoring data are here on page 35.

    See that the four Mont Blanc glaciers were in retreat roughly around the 1950-1960 timeframe. See that in this timeframe the global temperatures also dropped, as well as the local temperatures in nearby Geneve.

    However correlation is not causation.
     
  11. Sep 2, 2009 #10

    Xnn

    User Avatar

    Andrea;

    You've mis-represented your own reference! There was no retreat of the Mount Blanc glaciers during the 1950 to 1960 period; the retreat occurred 10 years earlier that what you've stated. Check out the actual text from the reference:
    Notice from the below graph, that the 1940 to 1950 period was at the time, a period of rising global temperatures.

    attachment.php?attachmentid=20365&stc=1&d=1251943175.gif

    http://www.ncdc.noaa.gov/img/climate/research/global-jan-dec-error-bar-pg.gif
     

    Attached Files:

  12. Sep 3, 2009 #11
    A statement like that would cost me 3 infraction points for misinformation but if it support alarmism one probably gets away with it.

    Check the time in the blue interval. same ref page 35 again.

    r90mrc.jpg

    Is that no retreat in concurrence with the local temperature as measured in nearby Geneve?

    5u4h9g.jpg
     
    Last edited: Sep 3, 2009
  13. Sep 3, 2009 #12

    Mk

    User Avatar

    This type of behavior is common in tropical glaciers, such as the one on Mt. Kilimanjaro's Kibo Peak (Tanzania), and the Quelccaya ice cap in the Peruvian Andes.

    Glaciologists Mote & Kaser write in a 2007 American Scientist article:
    http://www.americanscientist.org/is...-of-kilimanjaro-can-global-warming-be-blamed/

    What? Only indirect if any trends in global climate? What?

    20085291220246712-2007-07MoteF6.jpg
    Weather balloon summit altitude data indicates monthly average temperatures have fluctuated from -4 to -7 degrees since 1958, and no significant warming trend is seen. This is a problem for the argument that rising air temperature is responsible for the melting of this glacier. If the air temperature never rises above -4 degrees Celsius, the air cannot warm the ice to melting. (page 5)

    The researchers propose an alternative explanation, based on a keener understanding of how glaciers work.

    Tropical glaciers occur when mountain summits penetrate the subzero air of the upper troposphere. Snow precipitation helps them grow, and melting makes them retreat. Retreat is due to sublimation, or solar radiation in conditions of very light wind, which allows a warm layer of air to develop just next to the ice.

    As these forces whittle away at the glacial edges, steep walls are created. "Once developed, the near-vertical edges will retreat until the ice is gone, since no snow can accumulate on these walls." They see the steep walls and sharp peaks as evidence against the role of "smoothers"—diffuse heat sources.

    kilimanjaro_ice_spire.jpe
    20085291226586715-2007-07MoteF9.jpg
    Penitents at Kilimanjaro.

    Observers have been tracking the shrinkage of Kilimnajaro's glacier ever since Europeans first scaled the peak in the 1880s, but the ice cap at that time may have been unusually large following several decades of above-normal precipitation. Judging from Lake Victoria's water level, the climate in the region has gotten progressively drier since the 19th century. "Overall, the historical records available suggest that the large ice cap described by Victorian-era explorers was more likely the product of an unusually wet period than of cooler global temperatures."

    Ironically, if smoothers strengthened, if the air temperature rose occasionally above 0˚, the slopes would smooth out and sharp corners would gentle, allowing the ice cap to hold on to more snowfall. If precipitation could accumulate to a level that it would well cover the dark volcanic ash, and not melt by next season, the glacier's retreat would reverse.
     
    Last edited: Sep 3, 2009
  14. Sep 4, 2009 #13

    Xnn

    User Avatar

    In light of the Kilimanjaro article, it's interesting to note that December-February precipitation is actually projected to likely increase in that area of the world over the long term with June to August precipitation projected to remain essentially the same.

    See Pages 859 and 869 of the following link for details:

    http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter11.pdf


    So, what is currently happening is worse and somewhat at odds with the models.
    I say somewhat since the models are for the long term future and what's been observed is the recent past.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Glaciers that grew when temperature increased
  1. Melting glaciers (Replies: 12)

  2. Himalayan glaciers (Replies: 39)

  3. Glacier calving (Replies: 2)

Loading...