Roundup: Teaching Tourists, Landing Safely, Watching Cracks

Each week, we highlight three stories from the forefront of glacier news.

Climate Change Education for Mendenhall Glacier Tourists

Mendenhall Glacier with visitors (Alaska.org)
Mendenhall Glacier with visitors (Alaska.org)

From KTOO: “On a busy summer day, thousands of people — mostly cruise ship passengers — visit Juneau’s Mendenhall Glacier. The U.S. Forest Service wants those tourists to take in the dramatic views, but also consider why the glacier is shrinking. Visitor center director John Neary is making it his personal mission. That means trying to make the message stick — long after the tourists are gone…“It became our central topic really just in the last few years,” said Neary. He’s not afraid to admit he’s on a mission. He wants the more than 500,000 people who visit the glacier each year to know that it’s rapidly retreating due to climate change, and the 18 interpreters who work for him are prepared to talk about it.”

More on Mendenhall here.

Pemberton Icefield Glacier Breaks the Fall of a Crash-Landing in Canada

Plane landing on Pemberton Icefield (Twitter, @NEWS1130)
Plane landing on Pemberton Icefield (Twitter: @NEWS1130, @CFOperations)

From Weather.com: “‘We tried to accelerate — that was the end of the valley, like cul de sac.’ Jedynakiewicz. told the CBC . ‘I say, ‘Full power! Full power!’ But the plane doesn’t respond. I checked in the last second, the speed it was 40 miles [per hour] when [we made] impact with the ice. It was a soft landing, soft like on a pillow. Believe me.’ The impact knocked out the plane’s radio, Toronto Metro reports, but left the plane almost undamaged and the three men unhurt. ‘I think the wing tips only missed the rock pile by about a foot,’ Hannah told the Metro. There was rocks on one side and a waterfall right in front of us and we jumped over the waterfall (to reach the glacier). So it was touch and go all right. It was a miracle. First thing was say, ‘Oh, God thank you we are alive,’” Jedynakiewicz told the CBC. ‘Not even scratch can you imagine? Three of us.’”

Learn more about the emergency landing here.

Greenland Glacier Becoming Increasingly Unstable

Landsat-8 image of Greenland’s Zachariae Isstrom and Nioghalvfjerdsfjorden glaciers, acquired on Aug. 30, 2014. (NASA/USGS)
Landsat-8 image of Greenland’s Zachariae Isstrom and Nioghalvfjerdsfjorden glaciers, acquired on Aug. 30, 2014.
(NASA/USGS)

From Albany Daily Star: “A glacier in northeast Greenland that holds enough water to raise global sea levels by more than 18 inches has come unmoored from a stabilizing sill and is crumbling into the North Atlantic Ocean. Losing mass at a rate of 5 billion tons per year, glacier Zachariae Isstrom entered a phase of accelerated retreat in 2012, according to findings published in the current issue of Science. “North Greenland glaciers are changing rapidly,” said lead author Jeremie Mouginot, an associate project scientist in the Department of Earth System Science at the University of California, Irvine. “The shape and dynamics of Zachariae Isstrom have changed dramatically over the last few years. The glacier is now breaking up and calving high volumes of icebergs into the ocean, which will result in rising sea levels for decades to come.” The research team – including scientists from NASA’s Jet Propulsion Laboratory and the University of Kansas – used data from aerial surveys conducted by NASA’s Operation IceBridge and satellite-based observations acquired by multiple international space agencies (NASA, ESA, CSA, DLR, JAXA and ASI) coordinated by the Polar Space Task Group.”

For more, visit the Albany Daily Star’s Report.

If You Can’t Handle the Heat – Retreat

Zachariæ Isstrøm, a large glacier in the northeast coast of Greenland, is in a state of accelerated retreat after it detached from an important sill. This shift has caused great instability for the glacier, according to a new study from Science Magazine.

Recognizing 0.5 meters of possible sea level rise held within Zachariæ, and its acceleration expected to continue, the authors point to an increased likelihood of sea level rise coming from this area in the next 20 or 30 years. This study is noteworthy since Zachariæ is found far north, close to 79 degrees N. The Greenland glaciers which have been highlighted for their fast retreats to date are found further south. 

Zachariæ Isstrøm retreat (2003-15) captured by NASA/USGS Landsat satellite (Courtesy of :NASA/USGS)
Zachariæ Isstrøm retreat (2003-15) captured by NASA/USGS Landsat satellite (Courtesy of :NASA/USGS)

Jeremie Mouginot from the University of California, Irvine and his coauthors looked specifically at the effects of warming ocean and air temperatures on the melting and discharge dynamics of the glacier. (More Greenland work from the UCI team can be found here.)

The precise measurements of the ice discharge data were made possible by NASA, who provided funds and much of the data and equipment. 

Zachariae Isstrom and Nioghalvfjerdsfjorden - a similar glacier currently seeing less drastic changes (Courtesy of :NASA/USGS)
Zachariae Isstrom and Nioghalvfjerdsfjorden – a similar glacier currently seeing less drastic changes (Courtesy of :NASA/USGS)

The researchers observed a 50% increase in the retreating speed since 2000. There was also a doubling of ice thinning. On the ice shelf, this process was extensive enough to be measured by satellites. Data showed Zachariæ in a stable state up until 2003 when a large piece broke off. Since that breaking point Zachariæ retreated at a steady state until 2013-14 when the retreat accelerated. It is now retreating at a rate of 125 meters per year and losing 5 gigatons of mass yearly.

The increased mass loss is attributed by the authors to a combination of warming air and ocean temperatures. These changes lead to increased ice loss by way of calving, as opposed to changes in the accumulation of mass through precipitation. 

Ocean temperatures play an important role in glacier retreat; the authors argue that the nearly 1 degree C increase in ocean temperatures near the glacier is largely responsible for triggering the enhanced retreat.

Warming air temperatures lead to an increase in ice thinning which affects the placement of the grounding line below the surface – an important transition area where the glacier begins floating.  As the grounding line retreats there is increased surface area of the glacier exposed to the melting from below. Zachariæ began to calve so rapidly at the grounding line in 2014 that the remaining ice shelf was “95% smaller than in 2002” according to the researcher’s Landsat optical imagery data.

The authors did speak of another glacier in the Northeast of Greenland that is also experiencing accelerations-Nioghalvfjerdsfjorden Glacier (NG). Though the overall changes on NG were not as rapid as Zachariæ, the authors suggest that NG will become more vulnerable in the future.

A tidewater glacier, Margerie Glacier, in Glacier Bay Alaska.(Courtesy of :LH Wong/Flikr)
A tidewater glacier, Margerie Glacier, in Glacier Bay Alaska.(Courtesy of :LH Wong/Flikr)

“Not long ago, we wondered about the effect on sea levels if Earth’s major glaciers were to start retreating,” said one of the authors, Eric Rignot. “We no longer need to wonder; for a couple of decades now, we’ve been able to directly observe the results of climate warming on polar glaciers. The changes are staggering and are now affecting the four corners of Greenland.”

Isstrøm, a Danish phrase that translates as ice stream, seems to take on a poetic meaning when one thinks of the drastic amount of ice now “streaming” from the glacier.

As Zachariæ transitions into a tidewater glacier, it can be expected to calve more icebergs and become more vulnerable to increases in ocean temperatures. With other glaciers in this area retreating quickly Greenland will be an important region to watch in the coming decades, the authors concluded.

Here is a quick video illustrating how the position of the grounding line can accelerate retreat of a glacier by increasing the area exposed to currents.