Glacier Calving

June 30, 2009
Terminus of Columbia Glacier in 2005, showing the 300 foot ice cliff standing above the water. The ice extends another 1500 feet below the water to the ocean floor.

Terminus of Columbia Glacier in 2005, showing the 300 foot ice cliff standing above the water. The ice extends another 1500 feet below the water to the ocean floor. All photos Tad Pfeffer. Black and whites from"The Opening of a New Landscape: Columbia Glacier at Mid-Retreat” (W.T. Pfeffer, American Geophysical Union, 2007)

Alaska’s Columbia Glacier, which spills into Prince William Sound, continues to retreat at a rapid pace, as scientists strive to better understand the dynamics between iceberg calving, glacier sliding, and the ocean water that the glacier flows into. As the glacier moves into the water—at a current rate of about 16 meters per day—it loses mass by calving at a higher rate, causing a significant retreat that’s been documented since the late 1907s.

Columbia Glacier Terminus, June 2008.

Columbia Glacier Terminus, June 2008.

The University of Colorado’s Dr. Tad Pfeffer and a research team are documenting the glacier’s activity through field work and a photogrammetric study as part of a comprehensive NSF-funded project while public outreach (via the Extreme Ice Survey) is supported by a variety of sponsors, including NSF, NASA, National Geographic, and Nikon. In addition to documenting the rates of retreat, the team is filming time lapse sequences, and using photogrammetry and seismology to delve into the relationships between oceanography, calving, and the role those two processes have in accelerating the glacier’s disappearance.

Helicopter pilot Jim Harvey (Air Logistics) moving sling loads at Columbia Glacier, June 2004

Helicopter pilot Jim Harvey (Air Logistics) moving sling loads at Columbia Glacier, June 2004

The Columbia Glacier isn’t shrinking just because the ice is melting, the cause of retreat in landlocked glaciers. Rather, the Columbia, and other ocean-ending glaciers around the world, are winnowing down because they dump (or calve) enormous quantities of ice into the ocean. To date, scientists have only a vague understanding of the complex dynamics that occur between calving glaciers and the saltwater that laps at their bases, said Pfeffer. Decoding that relationship could dramatically increase the accuracy of rising sea level predictions.

Heavy crevassing showing accelerated flow above the marine-grounded fiord, Columbia Glacier, June 2008

Heavy crevassing showing accelerated flow above the marine-grounded fjord, Columbia Glacier, June 2008

“We don’t have a really robust way of writing down how calving works in quantitive physical terms we can put into a numerical model,” said Pfeffer. “Calving is a very complicated process. We’re still at the point of trying to understand exactly what’s happening.”

So far scientists know that calving outlet glaciers act to drain glacier and ice sheet interiors when accelerated flow upstream accompanies increased calving and flow at the terminus. Calving and increased flow speed, both naturally-occurring processes, can accelerate if the ice at the tidewater melts, thins, and loses contact with the bed. Simultaneously, the ice higher on the glacier can also speed up and thin. Though scientists don’t understand exactly how and why this occurs, they know it results in a cycle of acceleration, thinning, and more acceleration.

“Something about how the glacier interacts with the ocean affects it higher up,” said Pfeffer. “That is one of the mysteries we would really like to solve.”

Evidence shows a history of retreat among the Alaskan tidewater glaciers. For instance, since it began retreating in 1982, the Columbia glacier has backtracked 11 miles, about half the length of the fjord it occupies. In addition the glacier has shrunk from its 1982 size of 1,000 square kilometers and 60 kilometers long to 750 square kilometers and 42 kilometers long, and has lost an average of about four cubic kilometers per year since 1982 through calving.

Pfeffer said this process, while a naturally-occurring phenomenon, is likely triggered by climate warming and then perpetuated by natural cycles. If he and other researchers can quantify the physics of what’s happening in a computer model, they would contribute a more effective and accurate way to predict sea level rise as calving retreat continues to increase, not only in Alaska, but elsewhere in the world, including the major glaciers draining Greenland and Antarctica.

“Calving has become something that people recognize as very important because it is a very effective way of reducing glacial volume, and one that can be triggered by climate change but not controlled by it,” said Pfeffer.

Extreme Ice Survey team members Michael Brown and Jeff Orlowski fiming for the NOVA/National Geographic program Extreme Ice, June 2008

Extreme Ice Survey team members Michael Brown and Jeff Orlowski fiming for the NOVA/National Geographic program Extreme Ice, June 2008

To continue the search for an explanation, Pfeffer and his team will return to the Columbia Glacier in late August to continue the field work and photography. In addition to the measurements, the team will also employ airborne radar bed profiling, time-lapse photography and GPS to help elucidate the complicated tidewater/glacial dynamics.


Summer Flowers

June 29, 2009

Earlier this season, Greenland received a royal visit by the heirs to the Danish, Norwegian and Swedish thrones.  Our staff in Kangerlussuaq attended a dinner at the Row Club held in honor of the young royals. Here’s what they found on the banquet table:

Whale Carpaccio

Whale carpaccio

We’re told the whale carpaccio was particularly luscious, rich and delicate at the same time.

Thin slices of salmon encircle tender white asparagus.

Thin slices of salmon encircle tender white asparagus

Some caption here

Fish steamed with juniper berries

Another caption here.

Roasted caribou--surprisingly mild!

Photos: Susan Zager


Life At Toolik

June 26, 2009

Emily Stone is a Chicago-based freelance writer. She’s on a 16-day science journalism fellowship at Toolik Lake through the Marine Biological Lab (MBL).

We’ve been here almost a week, yet I’m still surprised by the same two things each morning when I walk out of my tent: I can see beautiful snow-covered mountains over the buildings from the front door, and I have to go to two separate spots to brush my teeth and go to the bathroom.

A weathered sign informs visitors about Toolik.

A weathered sign informs visitors about Toolik.

Life at Toolik is shaped by the remoteness of its location. This means that it attracts a hardy crew who don’t mind being dirty and in close confines for weeks on end because they realize how lucky they are to be here. And it means that it’s incredibly expensive to ship supplies in and waste out. Hence the lack of flush toilets in camp.

It costs so much to truck out wastewater that we’re given water rations. Instead of toilets, there are three sets of outhouses, dubbed “the towers,” which are raised above large collection tanks with three separated seats each.

The Toolik "towers," aka outhouses are stationed at three points around the station.

The Toolik "towers," aka outhouses are stationed at three points around the station.

There are no sinks there, just dispensers of hand sanitizer. A trailer in the middle of station houses the washeteria, with sinks, showers and laundry machines. We are limited to two, two-minute showers a week and one load of laundry every two weeks. A sign on the washing machines says that each load of costs $22.50.

Most people use trips to the sauna to clean up in lieu of regular showers. There are separate men’s’, women’s’ and co-ed hours and the sauna is down a slope at the edge of station where it’s hidden from view for modesty’s sake. The sauna has a window in it that looks out over the Brooks Range. A drum of slightly heated water on the deck is available for washing and rinsing, and most people chose to jump in the lake before or after washing.

Living quarters are mostly half-moon shaped tents that sleep six, though we’ve got only four in ours. The only furniture inside are cots. There are a few metal-sided dorms with double rooms, which I haven’t seen. Most of the labs are in trailers, though we’re working out of a tent similar to the one where we’re sleeping.

My tent, which I share with four other women, makes for cozy lodgings.

My tent, which I share with four other women, makes for cozy lodgings.

The dining hall is a center of activity. The food has been amazing. Tonight was Indian, last night paella. They leave leftovers in a fridge and you can help yourself to those or the array of cereal, candy bars, fruit and extra homemade dessert anytime you like. (We had to give our weights before a helicopter ride yesterday and we all rounded up.)


Postcards from Toolik

June 25, 2009
Emily Stone is a Chicago-based freelance writer. She’s on a 16-day science journalism fellowship at Toolik Lake through the Marine Biological Lab (MBL).
This is the small stream that leads into the Toolik River that formed a thermokarst several years ago. The green on the left side is actually the stream, which looks more like a marsh. Just below that, the stream opens up into a muddy canyon where the ground falls away in the thermokarst.

This is the small stream leading into the Toolik River that formed a thermokarst several years ago. The green on the left side is actually the stream, which looks more like a marsh. Just below that, the stream opens up into a muddy canyon where the ground falls away in the thermokarst.

The trick with having a surface that sits on ice – which is what permafrost tundra is – is that if that ice melts, the ground falls away.

That’s what’s happening across the arctic in a phenomenon known as thermokarst. The underground ice melts, the water rushes away and the ground collapses into a sinkhole. That’s bad news for any buildings or roads that straddle a thermokarst. Now scientists are starting to study what it means for the ecosystems around the holes.

With a grant from the National Science Foundation, Breck Bowden of UVM is leading a team of 25 researchers studying the impact of thermokarsts around Toolik on everything from nearby rivers and streams, the microbes in the soil, the vegetation and the atmosphere. The group arrived on station and started their work in late June.

In a previous study, Bowden looked at old aerial photos of the area around Toolik from the mid-80s and compared them to satellite photos from 2006. He found twice as many thermokarst depressions in 2006 than 20 years earlier.

The journalist fellows visited a thermokarst this week on a stream that feeds into the Toolik River. Above the thermokarst, the stream looked like a marsh as the water ran through tall, bright green grass. At the thermokarst, the stream suddenly opened up into a large, muddy chasm clear of plants. It was obvious that an enormous amount of soil had fallen into the stream. Researchers are interested in what that soil is doing to the water in the stream and in the Toolik River just below it.

We took water samples and started running tests on them to see what the difference in nutrient levels was above and below the thermokarst. We’ve just started analyzing the data, but it looks like a significant amount of the nitrate in the Toolik River is coming from the thermokarst. More nutrients like nitrates likely mean increased algae and moss, which can quickly change the composition of the insects and fish in the river.


Visiting NEEM

June 25, 2009

Through Ed Stockard’s Viewfinder

Ed recently visited the deep ice core drilling camp, NEEM, out on the Greenland ice sheet, flying there with a group of media invited by the Air National Guard. Take a look.

Here the journalists are transported on snowmobile-towed sleds from the skiway and the LC-130 that has flown them to NEEM.

Here the journalists are transported on snowmobile-towed sleds from the skiway and the LC-130 that has flown them to NEEM.

The group toured the ice coring facility, two underground rooms with a tunnel between them.
This is the drilling trench. Despite the room's snow walls, temperatures were getting a bit too warm for the ice core. The NEEM team has installed air intake systems to help combat the heat.

This is the drilling trench. Despite the room's snow walls, temperatures were getting a bit too warm for the ice core. The NEEM team has installed air intake systems to help combat the heat. More on the actual drilling operation to come.

Three stories high, filled with comfortable furniture and ambient light (sometimes a little too much ambient light, per the NEEM Web site!), the NEEM dome houses the dining facility, lounging areas and computer work stations, even a few bunk beds for nappers. The top floor aerie is the home of the NEEM camp leader, who makes weather observations and communicates with the outside world while keeping an eye on the place from the perch.
Robbie Score also visited NEEM. Her general impression of the place is evident on her face.

Robbie Score waits for a bus in front of the NEEM dome. Her thoughts on the place in a future posting.

Inside the dome, the kitchen is a warm haven. A talented chef is an object of great affection at a field camp like NEEM, as Sarah Harvey, pictured below in the NEEM kitchen, can tell you.
If you're thinking the NEEM team eats dehydrated food warmed over a well-used portable stove, think again.

If you're thinking the NEEM team eats dehydrated food warmed over a well-used portable stove, think again.


Up in the Air

June 24, 2009

Through Ed Stockard’s Viewfinder

The view from the port-hole-style windows of an LC-130.

The view from the port-hole-style windows of an LC-130.

The above is “an unidentified glacier south of Rink Isbrae (icestream), location N 71 deg 27 min  W 51 deg 26 min,” Ed writes. “I was sharing this window with some enthusiastic journalists that prevented a clean shot.” We bet they also had a few window frames in their shots too, thanks to Ed.

"Dang dirty windows."

"Dang dirty windows." Ed shoots Rink Isbrae, where a Jason Box time-lapse camera continuously documents the changing icescape. "Note the large broken-off piece floating next to the tongue," Ed says.

Ed Stockard flew to the NEEM ice camp recently with a group of media personnel. He and colleague Robbie Score were able to photograph the NEEM tunnels, where all the action takes place. Stay tuned.


Calving Glaciers

June 23, 2009

In the past 100 years, glacial retreat has resulted in the formation of many freshwater lakes into which tumble mini-icebergs from the glacier in a process known as calving. As the ice chunks break away from the glacier, they—along with surface melting—contribute to the overall loss of glacial mass. Given the relatively recent phenomenon of freshwater glacial calving (as compared with tidewater calving, where a glacier terminates into an ocean fjord), scientists don’t yet understand the dynamics of how calving speeds up the rate by which glaciers recede.

Aerial photo of the glacial terminus by Chris Larsen

Aerial photo of the Yakutat glacial terminus (Chris Larsen). Glaciologist Roman Motyka and a team are studying the dynamics of glacial calving in freshwater lakes.

Enter University of Alaska glaciologist Roman Motyka and his research team. Through an extensive, three-year, National Science Foundation-funded research project on Yakutat Glacier in southeastern Alaska, the team is investigating how much of this glacier’s ice is wasting away due to calving versus surface ice loss. According to maps and old photos, the small pond at the foot of Yukatat Glacier expanded from a tiny seminal lake in 1900 to its present seven-mile-long lake.

“Why are these particular glaciers wasting away so fast?” asked Motyka. “What are the dynamics on these ice-marginal lakes, and as the lakes grow, will there be an acceleration of wastage, or not?”

Martin Truffer drills into the glacier to install monitoring equipment.

Martin Truffer drills into the glacier to install monitoring equipment.

Motyka and his team spent two weeks in May installing extensive monitoring equipment on the glacier to collect data including:

  • Thinning rates through surface mass balance, laser profiling, and photogrammetry
  • Ice thickness and bed geometry by radio echo sounding (RES) and lake bathymetry
  • Ice velocity and strain rates by continuous and campaign-style GPS, and by remote-sensing techniques
  • Changes in terminus position by photogrammetry
  • The lake environment, including water level fluctuations and water temperature.

    Team member Barbara Truessel sets up one continuous GPS unit in May

    Team member Barbara Truessel sets up one continuous GPS unit in May.

 

Barbara Truessel and Andy the Heli Pilot at the Mass Balance site.

Barbara Truessel and Andy the helo pilot at the Mass Balance site.

The collected data will be used to develop a lake glacier calving “law” that can be incorporated into dynamical models of glacier flow. The team will compare their observational and modeling results with data from other glaciers around the world through international collaborations.

The team will head back out to the field in July.