Antarctic Berg gets News, but Look to Greenland for Real Iceberg Impacts

August 2, 2017

peterman17

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Scientific American:

The world saw headlines about one of the largest icebergs ever calved a few weeks ago. But a smaller one on the other end of the globe might have bigger consequences.

The chunk of ice, which broke free in the Arctic last week, is more worrisome to climate scientists who are watching one of Earth’s largest glaciers shed pieces in a way that stands to raise sea levels.

Compared with the Delaware-sized iceberg that split off of West Antarctica earlier this month, this one is almost paltry — the size of three Manhattans or so. It came off the ice shelf that buttresses the Petermann Glacier at the height of seasonal warming in the Arctic region.

By contrast, the recent Antarctic iceberg, while massive, did not have a clear connection to climate. Even if it foreshadows the split-up of the ice sheet to which it was attached, it would not raise sea levels noticeably. The Arctic calving has a much clearer link to climate change.

Movement of the Petermann Glacier has sped up in recent years, dumping land-based ice into the ocean at a faster rate and drawing more ice down from the center of Greenland, said Laurence Dyke, a researcher at the Geological Survey of Denmark and Greenland. Meanwhile, the ice shelf that braces it and slows the rate of flow is disintegrating as climate change transforms the region.

“You could call it the canary in the coal mine. If that big glacier there is changing quickly, and it is, it’s a worrying sign for what’s happening in the rest of Greenland,” he said.

The iceberg itself is not particularly notable, according to Dyke. But it could lead to an expansion of major cracks upstream in the ice shelf, causing it to break up more quickly. Most troubling to researchers is a crack at the center of the shelf. It’s an unusual place for cracks to form, and it could connect to separate cracks forming at the sides.

The loss of the iceberg also brings the shelf to a state not observed in the 150 years of tracking the glacier — and potentially much longer, Dyke said. The ice shelf bracing the glacier lost major pieces in 2010 and 2012. Both those icebergs were the size of several Manhattans.

Land-based glaciers in Greenland are a primary contributor to global sea-level rise, and they’re expected to increasingly lose their mass in the future. Petermann accounts for almost 10 percent of the Greenland ice sheet; it alone could raise sea levels by a foot.

(here, a correction from Laurence Dyke:

Two slight amendments (which I expect arose from talking to Scott on a bad mobile line in a crowded area).

1) Petermann Glacier makes up 4-5% of the Greenland Ice Sheet by area (not 10%).

2) The glacier is not yet in its most retreated position for 150 years, that will happen when the large iceberg calves off.)

As Petermann retreats, it will draw down ice from the center of Greenland, all of which will have a direct effect on sea-level increase. Researchers have cautioned that sea levels could rise by 3 feet at the end of the century, but a more rapid disintegration of Arctic glaciers would make that number larger. A study published earlier this year in Natureshowed that the rate of melting in Greenland has increased fivefold in the last 25 years.

Surface temperatures in the region have risen, and that has spurred a greater rate of melting. There are other links to climate change. As the seas warm, they erode ice shelves from underneath.

“When you’ve got this double whammy effect of the ocean warming from beneath and atmosphere warming from the surface, it’s really chewing at this glacier,” Dyke said. “Ultimately, it’s why it’s having this big retreat.”

peterman17a

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Glaciologist Andreas Muenchow:

After two years I am stunned that the fancy technology still works, but the new data I received the last 3 weeks does worry me. The graph below compares ocean temperatures from May-24 through June-16 in 2017 (red) and 2016 (black). Ignore the salinity measurements in the top panel, they just tell me that the sensors are working extremely well:

peterman17b

he red temperature line in the bottom panel is always above the black line. The 2017 temperatures indicate waters that are warmer in 2017 than in 2016. We observed such warming for the last 15 years, but the year to year warming now exceeds the year to year warming that we observed 10 years ago. This worries me, but three features suggest a new ice island to form soon:

First, a new crack in the ice shelf developed near the center of the glacier the last 12 months. Dr. Stef Lhermitte of Delft University of Technology in the Netherlands discovered the new crack two months ago. The new rupture is small, but unusual for its location. Again, the Washington Post reported the new discovery:

petermann-crack

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Second, most Petermann cracks develop from the sides at regular spaced intervals and emanate from a shear zone at the edge. Some cracks grow towards the center, but most do not. In both 2010 and 2012 Manhattan-sized ice islands formed when a lateral crack grew and reached the central channel. The LandSat image shows such a crack that keeps growing towards the center.

petermann201705311

Segment of Petermann Gletscher from 31 May 2017 LandSat image. Terminus of glacier and sea ice are at top left. Click for Larger

And finally, let’s go back to the ocean temperature record that I show above. Notice the up and down of temperature that in 2017 exceeds the 2016 up and down range. Scientists call this property “variance” which measures how much temperature varies from day-to-day and from hour-to-hour. The average temperature may change in an “orderly” or “stable” or “predictable” ocean along a trend, but the variance stays the same. What I see in 2017 temperatures before breakfast each morning is different. The new state appears more “chaotic” and “unstable.” I do not know what will come next, but such disorderly behavior often happens, when something breaks.

I fear that Petermann is about to break apart … again.

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17 Responses to “Antarctic Berg gets News, but Look to Greenland for Real Iceberg Impacts”

  1. rabiddoomsayer Says:

    Is the temperature variation tidal pumping?

  2. vierotchka Says:

    It is happening, and one can see it, but most govrenments still either doubt or deny that global warming is anthropogenic and don’t really intend to do anything about it, or they symbolically do something at a snail’s pace. There is little to no political will, and that is most infuriating.

  3. redskylite Says:

    I have just read today’s news, most of the quality outlets report findings that parts of Asia would have heatwave temperatures that would be lethal without special protection in a few more decades (if we carry on business as usual carbon emissions).

    The same day I learn movements are underway in the U.S to restrict immigration to English speakers only. Also we have also used up our allocation of resource for 2017 on Earth overshoot day.

    Yesterday I watched my favourite T.V program “The Chase”, a 70+ year old retired school teacher recited a mnemonic to recall all the monarchs of England since 1028 AD in a few seconds. That really brought home how time goes by and how short of time we are. By the end of the century if we do not defeat this problem people will die in millions (because of inaction and complacency).

    The mnemonic . .
    (Can be sung to the tune of “Good King Wenceslas”.)

    Willie, Willie, Harry, Stee,
    Harry, Dick, John, Harry three;
    One, two, three Neds, Richard two
    Harrys four, five, six… then who?
    Edwards four, five, Dick the bad,
    Harrys twain VII VIII and Ned the Lad;
    Mary, Bessie, James the Vain,
    Charlie, Charlie, James again…
    William and Mary, Anna Gloria,
    Four Georges I II III IV, William and Victoria;
    Edward seven next, and then
    George the fifth in 1910;
    Ned the eighth soon abdicated
    Then George the sixth was coronated;
    After which Elizabeth
    And that’s the end until her death.

    The News . .
    In South Asia, a region of deep poverty where one-fifth of the world’s people live, new research suggests that by the end of this century climate change could lead to summer heat waves with levels of heat and humidity that exceed what humans can survive without protection.
    There is still time to avert such severe warming if measures are implemented now to reduce the most dire consequences of global warming. However, under business-as-usual scenarios, without significant reductions in carbon emissions, the study shows these deadly heat waves could begin within as little as a few decades to strike regions of India, Pakistan, and Bangladesh, including the fertile Indus and Ganges river basins that produce much of the region’s food supply.

    http://news.mit.edu/2017/deadly-heat-waves-could-hit-south-asia-century-0802

    • redskylite Says:

      Earth Overshoot Day lands today!

      Today marks the day when the planet has used up all its resources such as water, clean air and soils for the whole of 2017.

      The Global Footprint Network has calculated that ‘Earth Overshoot Day’ falls on 2nd August this year, claimed to be the earliest date yet.

      It suggests the world has used more ecological resources and services than nature can regenerate through overfishing, overharvesting forests and emitting more carbon dioxide into the atmosphere.

      That means every natural resource used from this day onwards is in effect unsustainable in the long term.

      French Ecology Minister Nicolas Hulot said: “We are living on credit and inevitably, at some point, we risk going from having rare resources to having resource shortages.

      http://www.energylivenews.com/2017/08/02/earth-overshoot-day-lands-today/

      • dumboldguy Says:

        Overshoot Day happens in June in the USA. And as Trump’s policies MAGA, it will occur progressively earlier each year.

        • Tom Bates Says:

          You may note the day also happened when Obama was president as well. the day has not change under Trump from what it was under Obama. Obama response was to fly around the world on vacation by private jet and buy a large home on the beach in Hawaii. Apparently he knows something you do not.

          • dumboldguy Says:

            Another moronic comment from Tom the Moron. Yes, Obama bashing is a pretty dumb response to this post and to comments about overshoot Day. Especially for those of that DO know something that Timmy-Poo apparently does not. That The Orange Horror has done far more jetting around to NY and his golf course in NJ and to Mar-a-lago than Obama ever did, and is on track to exceed Obama’s “vacationing” and expenses for it by a huge margin.


          • The Obamas bought an expensive home in DC. Their Hawaii home is a vacation rental. My daughter and granddaughter were lucky enough to stay there during a wedding party 2 weeks ago.

            http://paradisepointestates.com/

          • dumboldguy Says:

            Nice, although Trump would probably consider it to be a “dump”—-I didn’t see any gold-plated fixtures or gold leaf anywhere in the photo tour.

  4. Tom Bates Says:

    http://scrippsscholars.ucsd.edu/jseveringhaus/content/high-variability-greenland-surface-temperature-over-past-4000-years-estimated-trapped-air-ic

    Just the facts which shows this claim is just a bunch of hot air. Greenland has large temperature variations and the world has not ended

    • redskylite Says:

      But Tom, if you read the paper it concludes that if we continue with burning fossils then we will push the temperatures up above natural variability before the end of the century. That’s the whole point of these posts and discussions, we still have a small window of time to prevent mayhem for our next generations. Jeff Severinghaus (the author of the paper you have linked to and professional paleo-climatologist) warns of this quite clearly in the paper. This is why people are highlighting the extreme dangers of a warming planet, the difference from warm periods experienced over the past 4000 years to today is that our hockey stick is still going up, in other words there is no plateau or ending in sight. Can you not understand that ?. We are talking about the future, not the current 10 minutes in time.

      “For decades, climate scientists like Severinghaus have been urging the public to burn less fossil fuels, which emits the greenhouse gas carbon dioxide and holds heat in the atmosphere. Scientific models show that by doubling the rate of carbon dioxide in the atmosphere compared to the pre-industrial age, global temperatures will rise to the point that causes widespread drought, extreme weather, and poses an threat to human life as we know it.

      This is a quote from the lead author of the fine report that you posted, you should not draw the conclusion that complacency is in order. Use your grey matter, that’s what it is for.

      “As Earth weathered ice ages and hot spells across the past 1 million years, ice cores show that carbon dioxide levels ranged from just under 200 parts per million during the cold snaps to nearly 300 parts per million during warm cycles. Since the industrial age, CO2 levels have risen to the current levels of approximately 400 parts per million. A doubling from pre-industrial levels would bring us to about 600 parts per million and levels are rising at just over 2 ppm per year.

      With that amount of carbon spooled in the atmosphere, Severinghaus said the atmosphere will rise by 2 degrees Celsius. In addition, many climate experts agree that 2 degrees of temperature rise is the tipping point where changes in crops, water supply and disease can already cause widespread suffering.”

      http://news.medill.northwestern.edu/chicago/how-hot-will-it-get-18000-year-old-mystery-could-answer-todays-biggest-climate-question/

    • dumboldguy Says:

      Redsky suggests that Tom read the paper—-LOL, we all know that Tommy-Poo doesn’t read for understanding, but only to cherry-pick things that he can distort and misrepresent to advance his stream of stupid denier BS. I will do the same with some bits of TRUTH that he missed.

      From Tommy’s link: “Notwithstanding this conclusion, climate models project that if anthropogenic greenhouse gas emissions continue, the Greenland temperature would exceed the natural variability of the past 4000 years sometime before the year 2100”.

      From this Crock post (and Tommy doesn’t really read any of them, just uses them at a peg on which to hang his ignorant BS)

      “A study published earlier this year in Nature showed that the rate of melting in Greenland has increased five fold in the last 25 years”.

      “Petermann accounts for almost 10 percent of the Greenland ice sheet; it alone could raise sea levels by a foot”.

      “You could call it the canary in the coal mine. If that big glacier there is changing quickly, and it is, it’s a worrying sign for what’s happening in the rest of Greenland,”

      That’s the point here, Tommy—-what’s happening now and likely to happen in the near future, and your deluded denier BS obscures those truths. (But that’s your whole purpose, isn’t it?).


  5. Two slight amendments (which I expect arose from talking to Scott on a bad mobile line in a crowded area).

    1) Petermann Glacier makes up 4-5% of the Greenland Ice Sheet by area (not 10%).

    2) The glacier is not yet in its most retreated position for 150 years, that will happen when the large iceberg calves off.

  6. mockovak Says:

    I don’t believe I’ve seen this graphic on your site:

    [https://i.imgur.com/K85cDF1h.jpg]

    Global Sea Ice Area Spiral July 2017 [OC] i.imgur.com #GlobalWarming #ClimateChange

    ________________________________


  7. Two slight amendments (which I expect arose from talking to Scott on a bad mobile line in a crowded area).

    1) Petermann Glacier makes up 4-5% of the Greenland Ice Sheet by area (not 10%).

    2) The glacier is not yet in its most retreated position for 150 years, that will happen when the large iceberg calves off.

  8. dumboldguy Says:

    A short article on Petermann with some nice graphics and more info.

    https://www.earth.ox.ac.uk/~helenj/work/publications/Johnson_OceanChallenge2012.pdf


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