New Paper: Awakening Greenland Giant – Not So Jolly

March 17, 2014

Above, my interview from last summer with Dr. Alun Hubbard in Kangerlussuaq.  Hubbard described how a GPS device deep in the ice sheet’s interior was beginning to show significant movement.
Newly published evidence continues the story.

Nature Climate Change:

Abstract: .. Here, we show that the northeast Greenland ice stream, which extends more than 600 km into the interior of the ice sheet, is now undergoing sustained dynamic thinning, linked to regional warming, after more than a quarter of a century of stability. This sector of the Greenland ice sheet is of particular interest, because the drainage basin area covers 16% of the ice sheet (twice that of Jakobshavn Isbræ) and numerical model predictions suggest no significant mass loss for this sector, leading to an under-estimation of future global sea-level rise. The geometry of the bedrock and monotonic trend in glacier speed-up and mass loss suggests that dynamic drawdown of ice in this region will continue in the near future.

Kitasap Sun/AP:

Stability in the rapidly changing Arctic is a rarity. Yet for years researchers believed the glaciers in the frigid northeast section of Greenland, which connect to the interior of the country’s massive ice sheet, were resilient to the effects of climate change that have affected so much of the Arctic.

But new data published Sunday in Nature Climate Change reveals that over the past decade, the region has started rapidly losing ice due to a rise in air and ocean temperatures caused in part by climate change. The increased melt raises grave concerns that sea level rise could accelerate even faster than projected, threatening even more coastal communities worldwide.

“North Greenland is very cold and dry, and believed to be a very stable area,” said Shfaqat Khan, a senior researcher at the Technical University of Denmark who led the new study. “It is surprisingly to see ice loss in one of the coldest regions on the planet.”

The stability of the region is particularly important because it has much deeper ties to the interior ice sheet than other glaciers on the island. If the entire ice sheet were to melt which would take thousands of years in most climate change scenarios sea levels would rise up to 23 feet, catastrophically altering coastlines around the world.

Sea levels have risen 8 inches globally since the start of the 1900s, and current projections show that figure could rise another 3 feet by the end of this century.

Some recent research has suggested that Greenland’s ice loss may slow, but not all researchers agree. Jason Box, a glaciologist at the Geological Survey of Denmark and Greenland, said the new study presented a novel analysis of the region and that other factors such as soot could contribute to even more rapid melt in Greenland and other parts of the Arctic.

“These new measurements show that the sleeping giant is awakening and suggest given likely continued Arctic warming that it’s not going back to bed,” Box said in an email.

Greenland houses 680,000 cubic miles of ice in its ice sheet, which stretches up to 3 miles thick in some places and covers roughly three-quarters of the island. Glaciers stretch from this frozen mass in all directions, eventually meeting the sea. In the past 20 years, some of these glaciers, particularly in the southeast and northwest, have dumped ever increasing amounts of ice into the ocean. That water has accounted for more than 15 percent of global sea level rise over that period.

Since the mid-1960s, climate change has helped drive average air temperatures up about 3.6F across the Arctic, more than double the increase compared to midlatitudes. The rise in air temperatures has fueled a tumultuous decline in sea ice, which has also helped warm the region’s ocean waters. Around parts of Greenland, ocean surface temperatures rose 1.8-3.6F between 1990-2011.

While the northwest and southeast section of Greenland have dramatically lost ice, researchers believed the northeast section was holding its ground. From 1978-2003, that was true, but ice loss has accelerated rapidly since mid-2003.

The Zachariae glacier has long acted as a sentinel on the northeast coast of the island, keeping ocean waters at bay from a 370-mile long stream of ice that stretches into the heart of Greenland’s massive ice sheet.

But a series of unusually warm summers around 2003 started to trigger glacial melt. At the same time, a spike in ocean surface temperatures also helped melt sea ice that normally acts as a buttress for the Zachariae and other glaciers in northeast Greenland. Without reinforcement, the glaciers suddenly started to draw down more ice from on high and retreat faster.

(Dr Box described this process to me in 2012 at the American Geophysical Union conference in San Francisco – below)

That fueled a feedback loop by allowing the anomalously warm ocean water to flow under the glaciers, helping them slide further to the sea. The Zachariae glacier is particularly susceptible to this process because the land under it slopes downward for miles inland, potentially inviting more ocean water to slide under it and further destabilize the glacier.

By 2012, the snout of the Zachariae glacier had receded more than 12.4 miles from its 2003 position. In comparison, the Jakobshavn glacier, located in southwest Greenland and long considered one of the fastest-changing glaciers on the island, has retreated 21.7 miles over the past 150 years.

UPDATE:

RobertScribbler:

The Zachariae Ice Stream is a vast river of ice in the northeast section of Greenland. It terminates in two outlets through a broad and deep ice-choked bay facing the Fram Strait.

Throughout the 1990s and into the early 2000s, both warmer air and ocean water temperatures at the margins of Greenland began to speed up and destabilize glaciers all along Greenland’s southern, eastern and western coasts. But the northern glaciers remained relatively stalwart, continuing the rate of seaward motion observed over previous decades.

Then, starting in 2003, something ominous began to happen. A combination of sea ice loss, warming air and ocean temperatures began to affect the northern edge of the great ice sheet. Its speed of forward motion through its outlet bays began to increase. By 2012, the great glaciers were dumping 10 billion tons, or roughly ten cubic kilometers of ice into the ocean every single year. In just nine years the Zachariae Ice Stream had retreated a total of 20 kilometers toward the heart of Greenland. By comparison, the Jakobshavn Ice Stream, known to be Greenland’s fastest and located in South Greenland, has retreated 35 kilometers over the past 150 years.

(Greenland Ice Sheet velocity map as of 2010. Measures in red are in the range of 1,000+ meters per year. Note that ice sheet velocity is fastest at the glacial outlet face and that rapid ice sheet velocity now extends far into interior Greenland. The Zacharie ice stream, the most recent to show rapid acceleration, is indicated by the letter Z in the upper right hand corner of the image. Note how this ice stream plunges deep into the heart of Northern Greenland and that a rapid flow is now established all the way to the ice sheet’s core. Image credit: Joughin, I., B. Smith, I. Howat, and T. Scambos.)

 

6 Responses to “New Paper: Awakening Greenland Giant – Not So Jolly”


  1. […] Above, my interview from last summer with Dr. Alun Hubbard in Kangerlussuaq. Hubbard described how a GPS device deep in the ice sheet's interior was beginning to show significant movement. Newly p…  […]

  2. mspelto Says:

    The KItsap Sun is correct that for many years researchers thought the NE sector was more resilient. However, that period of years was over by 2005. We have been carefully watching these glaciers in the last 10 years because we have expected a change to come, such as on Zachariae . This paper better quantifies what has been evident for several years.

  3. adelady Says:

    I read a couple of things on this result and I wasn’t exactly ho hum about it, but I sort of added it to the mental pile and the bookmarks without much thought.

    Then.

    I saw a couple of items which brought out the implications of that NE region being regarded as stable for the previous 25 years. It hasn’t been included in the projections for sea level rise attributable to ice melt – because they didn’t think it would melt so quickly.

    “Considering that existing climate models typically do not consider northeast Greenland with future sea-level projections, the findings suggest that sea-level rise estimates may err on the high side, close to 3 feet or higher, said Khan.” http://www.eenews.net/stories/1059996221
    http://www.independent.co.uk/environment/climate-change/fears-of-faster-rising-global-sea-levels-as-stable-greenland-ice-sheet-starts-to-melt-9195769.html

    So that’s now in the yet-more-depressing news bookmarks.

  4. dumboldguy Says:

    All the video clips here were scary the first time, but the addition of the data from the Z glacier in the northeast is truly frightening. The accelerating movement of the ice all the way back to the center of Greenland is not good news.


  5. […] Human Warming Now Pushing Entire Greenland Ice Sheet into the OceanNew Paper: Awakening Greenland Giant – Not So JollyGreenland’s icecap loses stability var TubePressJsConfig = […]


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