Senior student graphs glacier recession for capstone project

Wrapping up the spring Chautauqua season at the Nolan Center this year, a Wrangell school senior presented the findings by her classmates and herself mapping the movements of Shakes Glacier.

Located about 30 miles northeast of Wrangell up the Stikine River, the glacier is an oft-visited site by residents and visitors touring the river system. Its meltoff feeding into Shakes Lake, the glacier is part of the wider Stikine Ice Field, of which LeConte Glacier is included.

Reyn Hutten this year was captain of the high school's Shakes Glacier Survey Team, which for four of the past six years since 2011 has sent students upriver to measure the feature's position. The survey team was unable to make it up to the glacier this past year due to low water levels. Along with students Sig Decker, Sam Prysunka, Garrett Miller, Josephine Lewis, Charley Seddon and Helen Decker this year, the group has learned to use surveying equipment in the field and has been measuring the position of the glacier's terminus, or where it meets the water, and the width of the lake at that point.

Shakes Glacier has been gradually retreating over the years, and for her senior capstone project Hutten wanted to make the team's findings available to the wider public as a way to repay the community for its support of the survey program. First making a presentation to the Northwest Scientific Association at its annual conference in Ashland, Oregon at the end of March, she used the Chautauqua format to deliver her data to Wrangell on April 20.

Hutton explained the team could not have done their surveying without extensive community assistance. Breakaway Adventures, school advisors Heather Howe and Jenn Miller, Forest Service staff, and R&M Engineering have all contributed guidance and resources to the program over the years.

Surveyor Greg Scheff in particular had been a source of support, Hutten said. A longtime proponent of the survey, he had taught the students how to properly use surveying equipment, and had been a part of their yearly trips.

"He was a huge help to our project," said Hutten. Sadly, Scheff was killed in a plane crash on Admiralty Island last April.

Hutten also received guidance from her parents, Martin and Karen Hutten, who are both biologists working for the United States Forest Service.

"My parents guided me a ton," she said. It had been her mother's suggestion that she take part in the NWSA conference.

"It was a total blast," she said. Hers was the only presentation dealing with glaciers, in a conference whose theme was on understanding and managing diversity, from landscapes to genes. "I got a lot of people listening to this poster presentation that I did."

There were 150 professionals and researchers there, some of whose work Hutten was already familiar with. She had been nervous beforehand, but like a cross-country race, Hutten said she quickly got into the run of things.

"It went super well. I did a lot of practice sessions," she said.

The poster was in some ways practice for her presentation in Wrangell, and was modified into a slideshow for the Chautauqua. The effort she put into her work had been substantial, and Hutten logged over 150 hours on the project in all.

To start with, she endeavored to map out the glacier's history beyond the students' own relatively recent measurements. To do this, Hutten turned to a variety of sources. This included aerial photos of the glacier over the past 80 years taken by the Navy, US Geological Survey and USFS. Additional imagery taken by satellites were obtained from Google EarthEngine and EarthExplorer. Terminus position data going as far back as the mid-16th century came from Dr. Rob Viens' 2001 dissertation at the University of Washington, which studied the Stikine Ice Field extensively.

"I ended up getting quite a bit, going back pretty far," she said.

At one point, the glacier had come down to the Stikine River itself, and for her project Hutten put together an aerial-view infrared map tracking its extent there in 1698 to the present. On average, through the middle of the 18th century until about 1948 the rate of terminal recession was about 26 meters per year.

Hutten reported that significant recession in the glacier's terminus began at that point, averaging about 107 meters per year. "This is really, really fast," she said.

Shakes Glacier retreated about two miles over the next three decades (see diagram), and about as much again from 1977 up to the present. Over the past decade though, recession of the terminus has stabilized somewhat. However, melting is still progressing.

"It looks to me like we are losing ice volume from the top of the glacier," said Hutten.

To try and determine the causes, Hutten turned first to variable data collection. Using average annual temperature data from the National Oceanic and Atmospheric Administration since 1919, the Weather Underground from 2012 to 2016, and data from the Wrangell Airport station, she determined an annual 10-year average temperature to minimize short term fluctuations. She also took into consideration lake width at the terminus and various lag times that could impact the glacier's recession in ranges of 15 to 60 years.

She graphed and compared these variables using linear regressions, and so concluded the 107 meter-per-year rate of recession for the glacier.

"While a correlation was not found between recession rate and average decadal temperature or glacial lake width, climate and geography may still have an effect," she wrote in her report. Other factors could be at play, such as the depth and shape of Shakes Lake, the glacial bed slope and glacial lag time.

"There are a lot of things at work there that can obscure any one variable," she explained.

"These variables might also be affecting ice volume loss, rather than terminus retreat, of Shakes Glacier. It would be necessary to evaluate these factors specifically, which is beyond Shakes Glacier Survey Team's current capabilities," Hutten concluded.

In future years, she would like to see the WHS Shakes Glacier Survey Team take measurements of additional variables such as lake depth and terminus height above the lake, which will further research capabilities. A partnership with University of Alaska researchers such as that done with Petersburg High School's LeConte Glacier Survey Team could also enhance their capabilities, Hutten said.

An explanatory video put together by her classmates was added to the survey team website at http://whsshakesglaciersurveyteam.weebly.com. As part of her project Hutten has also arranged to put the glacier data on public display at the high school, school district office, Nolan Center and Wrangell Ranger Station.

After graduation this year, Hutten plans to attend Dartmouth College in New Hampshire. She may begin studying biology, which could lead her down a medical-related path or could branch out into zoology, Earth sciences– most anything at this point.

"We'll see where it goes. But science is definitely going to be a part of it," she said.