Alaska’s Columbia Glacier expected to halt retreat in 2020

From the University of Colorado at Boulder more model output, but at least this is a testable hypothesis in the not too distant future. It also points to the fact that there is not a definitive linear relationship between CO2 and individual glacier retreat, if there were, it would continue unabated.

Columbia Glacier, Alaska

Columbia Glacier, Alaska (Photo credit: Wikipedia)

The wild and dramatic cascade of ice into the ocean from Alaska’s Columbia Glacier, an iconic glacier featured in the documentary “Chasing Ice” and one of the fastest moving glaciers in the world, will cease around 2020, according to a study by the University of Colorado Boulder.

A computer model predicts the retreat of the Columbia Glacier will stop when the glacier reaches a new stable position — roughly 15 miles upstream from the stable position it occupied prior to the 1980s. The team, headed by lead author William Colgan of the CU-Boulder headquartered Cooperative Institute for Research in Environmental Sciences, published its results today in The Cryosphere, an open access publication of the European Geophysical Union.

The Columbia Glacier is a large (425 square miles), multi-branched glacier in south-central Alaska that flows mostly south out of the Chugach Mountains to its tidewater terminus in Prince William Sound.

Warming air temperatures have triggered an increase in the Columbia Glacier’s rate of iceberg calving, whereby large pieces of ice detach from the glacier and float into the ocean, according to Colgan. “Presently, the Columbia Glacier is calving about 2 cubic miles of icebergs into the ocean each year — that is over five times more freshwater than the entire state of Alaska uses annually,” he said. “It is astounding to watch.”

The imminent finish of the retreat, or recession of the front of the glacier, has surprised scientists and highlights the difficulties of trying to estimate future rates of sea level rise, Colgan said. “Many people are comfortable thinking of the glacier contribution to sea level rise as this nice predictable curve into the future, where every year there is a little more sea level rise, and we can model it out for 100 or 200 years,” Colgan said.

The team’s findings demonstrate otherwise, however. A single glacier’s contribution to sea level rise can “turn on” and “turn off” quite rapidly, over a couple of years, with the precise timing of the life cycle being difficult to forecast, he said. Presently, the majority of sea level rise comes from the global population of glaciers. Many of these glaciers are just starting to retreat, and some will soon cease to retreat.

“The variable nature and speed of the life cycle among glaciers highlights difficulties in trying to accurately predict the amount of sea level rise that will occur in the decades to come,” Colgan said.

The Columbia Glacier was first documented in 1794 when it appeared to be stable with a length of 41 miles. During the 1980s it began a rapid retreat and by 1995 it was only about 36 miles long. By late 2000 it was about 34 miles long.

The loss of a massive area of the Columbia Glacier’s tongue has generated a tremendous number of icebergs since the 1980s. After the Exxon Valdez ran aground while avoiding a Columbia Glacier iceberg in 1989, significant resources were invested to understand its iceberg production. As a result, Columbia Glacier became one of the most well-documented tidewater glaciers in the world, providing a bank of observational data for scientists trying to understand how a tidewater glacier reacts to a warming climate.

Motivated by the compelling imagery of the Columbia Glacier’s retreat documented in the Extreme Ice Survey — James Balog’s collection of time-lapse photography of disappearing glaciers around the world — Colgan became curious as to how long the glacier would continue to retreat. To answer this question, the team of researchers created a flexible model of the Columbia Glacier to reproduce different criteria such as ice thickness and terminus extent.

The scientists then compared thousands of outputs from the computer model under different assumptions with the wealth of data that exists for the Columbia Glacier.

The batch of outputs that most accurately reproduced the well-documented history of retreat was run into the future to predict the changes the Columbia Glacier will most likely experience until the year 2100. The researchers found that around 2020 the terminus of the glacier will retreat into water that is sufficiently shallow to provide a stable position through 2100 by slowing the rate of iceberg production.

The speediness of the glacier’s retreat is due to the unique nature of tidewater glaciers, Colgan said. When warming temperatures melt the surface of a land glacier, the land glacier only loses its mass by run-off. But in tidewater glaciers, the changes in ice thickness resulting from surface melt can create striking changes in ice flow, triggering an additional dynamic process for retreat.

The dynamic response of the Columbia Glacier to the surface melt will continue until the glacier reaches its new stable position in 2020, at roughly 26 miles long. “Once the dynamic trigger had been pulled, it probably wouldn’t have mattered too much what happened to the surface melt — it was just going to continue retreating through the bedrock depression upstream of the pre-1980s terminus,” Colgan said.

Colgan next plans to attempt to use similar models to predict when the Greenland glaciers — currently the major contributors to sea level rise — will “turn off” and complete their retreats.

The future for the Columbia Glacier, however, looks bleak. “I think the hope was that once we saw climate change happening, we could act to prevent some irreversible consequences,” Colgan said, “but now we are only about eight years out from this retreat finishing — it is really sad. There is virtually no chance of the Columbia Glacier recovering its pre-retreat dimensions on human time-scales.”

###

The study was funded by NASA, and co-authors on the paper include W. Tad Pfeffer of CU-Boulder’s Institute of Arctic and Alpine Research, Harihar Rajaram of the CU-Boulder Department of Civil, Environmental, and Architectural Engineering, Waleed Abdalati of the National Aeronautic and Space Administration in Washington, D.C., and Balog of the Extreme Ice Survey in Boulder, Colo.

The complete study is available online at http://www.the-cryosphere.net/6/1395/2012/.

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23 Responses to Alaska’s Columbia Glacier expected to halt retreat in 2020

  1. Bill says:

    Really? It’s sad that a mountain of ice will only be 26 miles long instead of 41 miles long?

  2. Glacier speed is governed by the mass of ice driving them downhill. If speed increases then calving will increase at the sea where the glacier becomes a shelf unsupported below by the land. To increase ice mass needs increased precipitation, ie snow.
    Perhaps their model needs to be modified to include increased snow upstream.

  3. AleaJactaEst says:

    and did the authors input a valid temperature data set into the model?. note the weasel-wording “Warming air temperatures have triggered an increase in the Columbia Glacier’s rate of iceberg calving,” citation please – has the local air temperature indeed warmed over the timescale of the study?? Perhaps a deceleration of calving indicated by the models is related to flat global temperatures for the last decade?? and I’ll hold them to this; put it in my diary for 2020. “There is virtually no chance of the Columbia Glacier recovering its pre-retreat dimensions on human time-scales” we’ll see shall we?

  4. Jeff Alberts says:

    It’s better than we thought?

  5. RHS says:

    Even the National Park Service identifies that Alaska Glaciers have been retreating since 1750 – 1780, the end of the Little Ice Age. They changed their FAQ page for the Tongass National Forest which specifically stated the above. If I can find a new one, I’ll post a link. It used to be here:
    http://www.fs.fed.us/r10/tongass/forest_facts/faqs/faqs.shtml

  6. Gail Combs says:

    Models, Models, Models.

    Here is the North American Snow Cover for October (graph1970 – 2012) and an interesting story on snow in alaska this spring/summer AccuWeather.com: August 06, 2012: Endless Winter for Alaska’s Mountains This Year

    If I recall correctly AccuWeather was the group who alerted NYC/NJ of the dangers of Sandy and spurred the evacuations.

  7. Steve Keohane says:

    It appears they are claiming a 2°C warming of air temperature in the region. Seems unlikely from the temperature measurements.
    http://climate.gi.alaska.edu/ClimTrends/Change/7711Change.html

  8. Rhys Jaggar says:

    ‘The future for the Columbia Glacier, however, looks bleak. “I think the hope was that once we saw climate change happening, we could act to prevent some irreversible consequences,” Colgan said, “but now we are only about eight years out from this retreat finishing — it is really sad. There is virtually no chance of the Columbia Glacier recovering its pre-retreat dimensions on human time-scales.”

    Why is this a tragedy?? It’s perfectly conceivable that this glacier’s centennial/millennial cycles do precisely what is going on now: retreat several kilometers, then advance several kilometers.

    Do we have data as to where this glacier’s terminus was in the Medieval Warm Period, the Roman Warm Period, the ones before that??

  9. John West says:

    “There is virtually no chance of the Columbia Glacier recovering its pre-retreat dimensions on human time-scales.”

    SO?

    There’s virtually no chance of Pangaea reforming on human time scales either (really sad /sarc). Is he suggesting we should “do something” in order to preserve a glacier in some sort of “perfect” state? Another example of why activism and science are incompatible. News flash: mountains erode, rivers flood, valleys rift (some), oceans form, mountains rise, volcanoes erupt, glaciers retreat, glaciers advance, species become extinct, the world turns.

  10. gator69 says:

    “There is virtually no chance of the Columbia Glacier recovering its pre-retreat dimensions on human time-scales.”

    Since when have glaciers concerned themselves with Gregorian calendars?

  11. Ron C. says:

    Headlines from Doha COP 18 show that the permafrost bogeyman has been trotted out. Once again alarmists are in massive denial of the facts.
    1) Permafrost has an active layer that can vary between two to three feet in a typical place like Barrow AK. That layer has melting and freezing every year.
    The methane concentration have been flat in Barrow in recent decades.

    2) Permafrost depletion in NH stopped in 2005.

    Except for warming during the 1970s and 80s, northern Eurasian temperatures appear to have remained fairly stable. And of that warming, Frauenfeld and Zhang state that “the strong decrease in seasonal freeze depths during the 1970s to “1990s was likely the result of strong atmospheric forcing from the North Atlantic Oscillation during that time period.” Thus, their work provides little to no evidence for any significant warming of this massive portion of earth’s land mass over the past two decades, and absolutely no evidence for recent CO2-induced warming.” [Oliver W Frauenfeld, Tingjun Zhang 2011: Environmental Research Letters]
    3) Researchers have discovered that when these melted areas are thawed, the explosion of new growth of vegetation becomes a positive CO2 sink that sequesters carbon dioxide in greater quantities than that released from the thaw. So instead of permafrost melting being a positive warming feedback, it actually becomes a negative feedback.
    “northern peatlands can continue to serve as carbon sinks under a warmer and wetter climate, providing a negative feedback to climate warming,” which is the exact polar-opposite of what has historically been claimed by the world’s climate alarmists.” [Shanshan Cai, Zicheng Yu 2011: Quaternary Research]
    4) Earlier warm periods, such as the Medieval and Holocene optimum, did not produce unusual amounts of CH4.
    “There appear to be no significant CH4-excursions in ice core records of Antarctica or Greenland during these time periods which otherwise might serve as evidence for a massive release of methane into the atmosphere from degrading permafrost terrains.”
    http://www.worldclimatereport.com/index.php/2007/05/24/cooling-the-permafrost-scare/

  12. E.M.Smith says:

    So the glacier had during an exceptionally cold Little Ice Age bridged a depression in the water that is unstable to modest floating ice. LIA ends, things slowly warm, and, surprise, they find that once the retreat hits the ‘dip’ and unstable area, it rapidly calves back.

    Oh, and it looks to me like water temperature and snow fall are much more important to this process than the air temperature. A glacier over water will have much more heat flow from the water than from the air (especially during those long frozen winters up north).

    “Once the dynamic trigger had been pulled, it probably wouldn’t have mattered too much what happened to the surface melt — it was just going to continue retreating through the bedrock depression upstream of the pre-1980s terminus,” Colgan said.

    So geologic shape and water contact look like the driving elements here. Air temperature not so much…

  13. dp says:

    We probably need a glacier named “Flipper”. Years ago when dolphins were being trapped in tuna nets, Flipper came to the rescue. Why nobody thought the tuna needed help against being trapped in the tuna nets was lost on the masses. It was later rationalized that the dolphins should be saved because they smile.

    We need a smiling glacier with a cute name so everyone will want to save it.

    /mindless greeny mode off

  14. Bruce Cobb says:

    “Many people Alarmist Climate Pseudoscientists are comfortable thinking of the glacier contribution to sea level rise as this nice predictable curve into the future, where every year there is a little more sea level rise, and we can model it out for 100 or 200 years,” Colgan said. There, fixed.
    Funny how they are always shocked and surprised by the fact that the real world doesn’t conform to their playstation climate models.

  15. Paddy says:

    Re Gail Combs: Isn’t permanent snowfields one of the early indicators of more extensive glacial ice formation? That appears to be happening in northern Alaska now. Comments please.

  16. DavidG says:

    These models are as worthless as the ones used by the warmers.

  17. Bruce Cobb says:

    This is a travesty. Once glaciers stop retreating, whatever will they have to wail and moan about? I suppose there’s always the poley bears. Oh wait, their numbers are higher than they were 30 years ago.

  18. The assumption is that warming atmospheric temperatures is causing the glaciers retreat. As the main cause is increased solar insolation from decreased aerosol seeded clouds their prediction is worthless.

    I wonder what they will do with their model when they encounter a north facing glacier in Greenland and find that it has advanced over recent decades.

  19. G P Hanner says:

    This morning, sitting in a doctor’s waiting room, I leafed through a National Geographic magazine from October 2011. One article was a breathless account of how carbon dioxide in the atmosphere warmed the environment to the point that methane hydrate crystals dissolved and released a gush of methane into the atmosphere, thus causing more warming of the atmosphere. This happened, the article claims, about 57 million years ago. No glaciers at all, the article claims. Sea levels some 225 feet higher than present, the article claims.

    But it’s just an article from the National Geographic magazine and has a few AGW issues it continues to promote.

  20. Hoser says:

    It’s a tidewater glacier, and even floated part of the time it was retreating. During that time, it couldn’t have contributed to sea-level rise. It is retreating because it lost it’s protection from the debris it pushed forward, that prior to 1980 protected the terminus from tidal action. Now it will probably retreat back to shore. I suppose it is possible the glacier could advance once more if it develops a new leading edge moraine.
    http://earthobservatory.nasa.gov/Features/WorldOfChange/columbia_glacier.php

  21. Mike Jonas says:

    I think the hope was that once we saw climate change happening, we could act to prevent some irreversible consequences,” Colgan said, “but now we are only about eight years out from this retreat finishing …

    So the glacier retreat will stop all on its own, without anyone doing anything.

    … — it is really sad.“.

    Why?

    A single glacier’s contribution to sea level rise can “turn on” and “turn off” quite rapidly, over a couple of years, with the precise timing of the life cycle being difficult to forecast, he said. Presently, the majority of sea level rise comes from the global population of glaciers. Many of these glaciers are just starting to retreat, and some will soon cease to retreat.
    “The variable nature and speed of the life cycle among glaciers highlights difficulties in trying to accurately predict the amount of sea level rise that will occur in the decades to come,” Colgan said.
    “.

    Here, surely he speaks the truth: they just don’t know what causes glaciers to change – and some glaciers change a lot: http://www.science-frontiers.com/sf038/sf038p12.htm

  22. Never hear anything about Hubbard Glacier, the largest tidewater glacier in North America. It has been advancing since the late 1800’s. Had a monitoring site, but can;t access now…

  23. Wyatt says:

    When I was a little kid, (60’s 70’s) the AK ferry used to race up and cause massive calving not only by wave surge but with sound waves from it’s air horn. I recall reading some study (on here) through rock radiation that the last time glaciers were receded this far was 700 to 1200 years ago, depending on hemisphere. That is from memory though so don’t quote me. I’m sure it’s still on here somewhere. Just got back from Hawaii and it is so cold in Alaska. There is zero GW this winter. Not sure why my grandparents moved here in the 40’s, though I’m sure I’ll remember by summer…

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