Studying a Melting World: Seventy Years of Glacier Records Threatened
Changing routes, inaccessible weather stations and an uncertain future.
For more than 70 years, scientists have woven a tapestry of glacial data from snowy expeditions, satellite imagery and dozens of marked-up yellow notebooks, all to better understand how glaciers respond to a changing climate.
Spanning decades, this data is a part of the longest-running and continuous project to monitor glacier change in North America: the U.S. Geological Survey Benchmark Glacier Project.
Today, the future of this record is at risk, impacting our ability to track glaciers, the heartbeat of Alaskaʼs mountains.
Twice a year, glaciologists travel to five glaciers in Montana, Washington and Alaska to take seasonal measurements of how much ice the glaciers gained in the winter and lost in the summer, otherwise known as glacier mass balance.
Today, the future of this record is at risk, impacting our ability to track glaciers, the heartbeat of Alaskaʼs mountains.
Twice a year, glaciologists travel to five glaciers in Montana, Washington and Alaska to take seasonal measurements of how much ice the glaciers gained in the winter and lost in the summer, otherwise known as glacier mass balance.
Glaciers lose mass in the form of meltwater, which directly impacts local and global communities. Since the turn of the century, glaciers have contributed to about 21% of global sea level rise, according to a 2021 study published in Nature. Alaska glaciers make up a quarter of the sea rise.
The Benchmark Glacier Project is one of few continuous records of how glaciers react to climate and temperature. The project provides critical data for modelling rising sea levels, global climate predictions and worldwide decision-making. Scientists at the U.S. Geological Survey Alaska Science Center in Anchorage are responsible for tracking these changes at three glaciers in Alaska. This includes Lemon Creek Glacier on the Juneau Icefield, Kenai Peninsula’s Wolverine Glacier, and Gulkana Glacier, a popular recreational spot southeast of Fairbanks.
These Alaska Benchmark Glaciers are a part of the only 60 glaciers worldwide with long-term and continuous monitoring for over 30 years.
Reaching the glacier measurement sites is a task in itself. Scientists take snowmobiles or helicopters or trek on foot to these glaciers each fall and spring to collect data, carrying sometimes more than sixty pounds of equipment on their backs and often traveling roped together in case snow bridges crumble beneath their feet.
Alaska glaciologists are having an increasingly difficult time tracking glaciers as historical routes change and disappear, critical weather stations become inaccessible and continued funding is uncertain.
“Wolverine Glacier, Gulkana Glacier and Lemon Creek Glacier are all going to be gone in 100 years. There’s going to be no ice left there at all,” said Louis Sass, the head of the Alaska Benchmark Glacier Project.
Sass and other glaciologists have spent decades recording how the glaciers are evolving, documenting these places before they disappear. As these glaciers rapidly lose mass, scientists need to adapt quickly – giving the term “glacial pace” a whole new meaning.
Losing, gaining, shifting routes: Navigating new glacial terrain
Alaska glaciers lose 66.7 billion tonnes of ice each year, enough to cover Manhattan in 270 feet of water, and this glacier melt is accelerating.
Scientists at the Benchmark Glacier Project are experiencing the effects of this loss firsthand, needing to assess their routes every season. Last fall, accessing Gulkana Glacier was hard work. As the glacier recedes, it is leaving endless fields of soft, silty mud, which makes getting to the glacier challenging.
“It’s almost like quicksand. To avoid it, you end up walking on this loose, unstable moraine,” Sass said.
In the 2000s, the silty field was about half the size of a soccer field. Now, Sass says it’s the size of more than a half dozen soccer fields.
At Wolverine Glacier, situated in the Kenai Mountains, a massive channel of milky blue meltwater burst from the side of the glacier in 2019, forming a seasonal lake. As of spring 2024, the access point scientists have used for over 50 years is now completely submerged underwater.
When geophysicist Chris McNeil joined the Benchmark Glacier Project 12 years ago, getting on the glacier was straightforward. They could access the glacier in minutes, using snowmachines to drive over snow-covered crevasses. In the past 10 years, the glacier has shrunk, making it increasingly harder to access. After the river appeared, McNeil and the team watched the lake grow further, creeping towards their typical access path.
Last fall, scientists found the Wolverine Glacier access point flooded and riddled with large crevasses. Seracs, attached columns of ice that slowly peel away from glaciers, towered hazardously over the path, threatening to give way. This past spring, they needed to find an entirely new route onto the glacier.
Their new route, however, was good news, at least for now.
“Honestly, what we found this past spring at Wolverine was an easier route than the thing that we had been doing for the last 10 years,” Sass said. “This year, it was hard enough … we needed to find something different. It turns out we found something that was more straightforward. Sometimes you can’t do what you did before, and what you find is more complicated. We found something that was great. That’s not always the story.”
Now the Benchmark Glacier Project team has to reassess their routes every year, sometimes on a seasonal basis.
“Every year, there’s this question of whether or not it’s going to be safe. And every year, it’s worked out okay, but you have to look at it really closely. And it is harder work than what we used to do,” Sass said.
For Sass, Wolverine Glacier “kind of feels like a new glacier every time I see it now.” Monitored by USGS since the late 1960s, this glacier has lost about 10% of its area since 1966 at an accelerating rate.
Rod March, a past glaciologist at the program, had been working for the Benchmark Glacier Project since the early 1980s. When Sass started in 2008, March showed him where Wolverine Glacier’s terminus was at the beginning of the 1980s. In almost three decades, it had barely moved.
According to the Fifth National Climate Assessment, Alaska is warming two to three times faster than the global average, and Alaska glaciers are losing more mass than anywhere else in the world. Since March left the program, Louis Sass said the glaciers they studied together changed drastically, far more than they had in the decades March worked for the project.
“I was talking to Rod March last year on the phone, telling him how much change we’d seen since he left here in 2012, and he was floored by that,” Sass said.
Lost weather station: Finding solutions at Mendenhall Glacier
Due to thinning ice, glaciologists on the Juneau Icefield face similar access challenges. As the ice continues to melt from Áakʼw Tʼáak Sít’ (Mendenhall Glacier), the glacier now sits far below the USGS weather station. Perched above Suicide Basin, the station is one of the sites used to monitor annual glacial lake outburst floods. Dr. Eran Hood, a glaciologist and professor at the University of Alaska Southeast now looks up toward the station and sees a hazardous cliff between him and necessary data.
“Now, it’s so difficult that we’ve mostly abandoned that site,” Hood said. As the glacier thins, it drops loose rock and boulders, creating an unstable terrain. Combined with hauling heavy equipment, it’s far more hazardous to get to the station, forcing researchers to avoid it altogether.”
USGS scientists now fly helicopters to the cliffside weather station, presenting its own series of hazards. Currently, USGS is developing plans for a helicopter pad to access it safely, which will require more time and resources.
“It’s important to understand that as the glaciers change, the way that we study them has to change as well,” Hood said.
An uncertain future
Two years ago, the Benchmark Glacier team was forced to decommission one of the longest running and highest weather stations in Alaska. This station was critical to understanding the relationship between weather and glacial change, using local measurements of temperature, precipitation and wind to help decipher the timing of these changes.
Situated along the margin of Gulkana Glacier, this station gathered weather data for more than 60 years. Unbeknownst at the time of its construction, it was built on top of an ice-cored moraine, an area of the glacier covered in sediment and rock. For decades, the moraine remained stable. In 2012, the team noticed the ice underneath melting, and quickly built Nunatak Weather Station.
“We did our due diligence; we created a new station, and there’s about 10 years of overlapping the data before decommissioning the old, so that’s the way that you try to bridge the old with the new,” said Emily Baker, a past glaciologist on the program. “It took a long time to build the value and long-term records of both the broader Benchmark Glacier Project and this weather station. You can really destroy things in an instant.”
In 2023, they helicoptered the station away in pieces.
“If we had left the weather station there, I think the whole thing would have actually slid down into a deep pile of rock,” Sass said.
Accessing weather data remains a continuous challenge for the team. Nunatak Weather Station is now getting harder and harder to access every year.
Paralleling rapid glacial changes, Sass and his team also have to consider the whirlwind of federal funding. Baker left her position in May 2025 due to unpredictable funding going forward.
“The huge uncertainty over the future funding of federal science has been traumatic, I would say, as an employee. I was there for over eight years … it was a long-term job that I found to be very fulfilling,” Baker said.
At Juneau Icefield’s Lemon Creek Glacier, fieldwork in spring of 2024 didn’t happen. This glacier is one of the longest running monitoring programs in the world, monitored jointly by USGS and the Juneau Icefield Research Program. Now, there’s talk of cutting fall monitoring on Lemon Creek Glacier all together.
“Once you miss a season of measurement, you can’t go and get it back. Anytime you have discontinuous data, it really messes up your ability to do some statistical testing. It’s bigger than losing just one year of data. It’s losing the continuity of the data, ” Baker said.
Funding issues aren’t new. In the early 2000s, a stream gauge employee at Washington’s South Cascade Glacier volunteered his time to take measurements for the Benchmark Glacier Project when funding fell through. For scientists at this program, measurements are personal.
“People really value these records emotionally. They want to see them continue. People have really put a lot of blood, sweat and tears into keeping this going,” Baker said.
But these measurements are bigger than the scientists. Five percent of Alaska is glaciated, roughly the size of the largest freshwater lake in the world, Lake Superior. With 33,000 square miles of ice, Alaska’s glaciers are projected to be the largest contributor to global sea level rise from warming temperatures of any glaciated region in the world.
Benchmark Glacier Project data is critical in informing how communities will adapt around the world to sea-level rise, destabilizing landscapes and changes in local water resource management. Their measurements are used in global decision-making, including reports from the Intergovernmental Panel of Climate Change.
“The data we collect exceeds the precision of anything that we can currently collect from space. As the cryosphere of the planet continues to change, it’s really critical that we continue to have these data sets on the ground,” McNeil said.
With the project losing more staff, getting these measurements will become more challenging. “I don’t think it’s a very controversial statement to say that if you don’t have the people to make the measurements, you won’t have the measurements,” Sass said.
As these glaciers recede, taking historic routes and weather stations with them, scientists now spend more time and resources rebuilding stations, revisiting plans and changing routes.
Weaving together all the uncertainties, glaciologists must adapt to continue creating this tapestry of shifting ice. As the glaciers change, so will they.
