Glacier Repeat Photography

Repeat photography is one of the tools that scientists use to study glaciers. Comparing historic pictures to current ones helps scientists to see the changes in the landscape over time. The repeat photography collection in Kenai Fjords National Park combines multiple photo collections with some of the earliest photos over 100 years old.
 

Bear Glacier in 1909 and 2021

A black and white photo.  The bottom half of the picture is water.  In the top half there is a large glacier in the center of center of the picture.  There are mountains on the right edge and left edge of the picture to the sides of the glacier. A black and white photo.  The bottom half of the picture is water.  In the top half there is a large glacier in the center of center of the picture.  There are mountains on the right edge and left edge of the picture to the sides of the glacier.

Left image
Bear Glacier located in Resurrection Bay.  Photo taken in 1909
Credit: USGS/ U.S. Grant

Right image
Bear Glacier, photo taken in 2021
Credit: NPS Photo/ H Beutler

Bear Glacier shows an astonishing amount of change in this photo series. Park physical science staff monitor the dramatic changes in this dynamic place.  This is a challenging photo to repeat due to the original photo’s low cloud ceiling resulting in few visible landmark features to help navigate to the original location.

 

Bear Glacier in 1990 and 2020

A glacier flowing between mountains down to the ocean.  There is a dark stripe running down the center of the glacier. A glacier flowing between mountains down to the ocean.  There is a dark stripe running down the center of the glacier.

Left image
Bear Glacier located in Resurrection Bay.  Photo taken in 1990
Credit: NPS Photo/M Tetreau

Right image
Bear Glacier, photo taken in 2020
Credit: NPS Photo/ E Kulack

Bear glacier is the longest glacier in the park and currently terminates at a proglacial lake.  It is only separated from the ocean by a narrow beach. It has increasingly attracted visitors for its sublime large icebergs that scatter the lake while the glacier retreats year after year.  If one looks at these two images, you can see not only the retreat of the terminus but also the thinning occurring across the entire glacier surface. Park physical science staff use very accurate 3D models acquired from remote sensing over time to quantify how Bear glacier is thinning.

 

Aialik Glacier in 1990 and 2016

A tidewater in 1990. The glacier is in the center of the image.  The bottom of the glacier is at the edge of water.  the glacier is between two mountainsides A tidewater in 1990. The glacier is in the center of the image.  The bottom of the glacier is at the edge of water.  the glacier is between two mountainsides

Left image
Aialik Glacier located in Aialik Bay. Photo taken in 1990
Credit: NPS Photo/M Tetreau

Right image
Aialik Glacier, photo taken 2016
Credit: NPS Photo/ D Kurtz

Aialik glacier sits at the head of Aialik Bay. The name Aialik comes from Sugpiaq, and means, “surprising place”.  The glacier is fed by the Harding Icefield, which lies 4 miles up from the face of the glacier.  While the face of the glacier has remained relatively stable, there is some surface thinning and retreating on its sides.

 

Pedersen Glacier in 1909 and 2020

A black and white photo. The bottom half of the picture is water.  Two mountains are on either side of htei mage, and a third mountain is faint in the background.  A white glacier is in the center of the image and comes to the waters edge A black and white photo. The bottom half of the picture is water.  Two mountains are on either side of htei mage, and a third mountain is faint in the background.  A white glacier is in the center of the image and comes to the waters edge

Left image
Pedersen Glacier located in Aialic Bay.  Photo taken in 1909
Credit: USGS/ U.S. Grant

Right image
Pedersen Glacier, photo taken in 2020
Credit: NPS Photo/ E Kulack

Pedersen Glacier is in Aialik Bay and terminates in a proglacial lake before the ocean. Over the years, Pedersen Glacier has steadily retreated towards its Harding Icefield source and out of the field of view in this photo. In the time that has passed between these two photos, Pedersen glacier has retreated roughly 3 miles and has helped transform the landscape we witness today. How do you think this place will change in the next 100 years?

 

Holgate Glacier in 1909 and 2019

A black and white photo.  The bottom half of the picture is water.  There are mountainsides on the right and left of the picture.  In the middle is a large glacier that meets the water. A black and white photo.  The bottom half of the picture is water.  There are mountainsides on the right and left of the picture.  In the middle is a large glacier that meets the water.

Left image
Holgate Glacier located in the Holgate Arm of Aialik Bay.  The photo was taken in 1909
Credit: NPS Photo/U Grant

Right image
Holgate Glacier, photo taken in 2019
Credit: NPS Photo/ E Kulack

Holgate glacier is in Holgate Arm and is one of the marquee features of Aialik Bay. U.S. Grant named the glacier when he was working for the USGS.  He named Holgate glacier after Dr. Thomas F. Holgate, Dean of the College of Liberal Arts of Northwestern University at the time. Although Holgate glacier has retreated and thinned since then, dynamic processes are at work that have caused the glacier to advance the past few years.

 

South Holgate Glacier in 1990 and 2019

A blue colored glacier flows over a mountainside and down to the water.  There are rocks and land in the water in front of the glacier A blue colored glacier flows over a mountainside and down to the water.  There are rocks and land in the water in front of the glacier

Left image
Surprise Glacier located in the Holgate arm of Aialik Bay.  Photo taken in 1990
Credit: NPS Photo/M Tetreau

Right image
Surprise Glacier, photo taken in 2019
Credit: NPS Photo/ E Kulack

South Holgate glacier, sometimes known locally as Surprise glacier, has undergone tremendous change that staff at the park and locals have witnessed with their own eyes. Since 2016, the bottom of this glacier has detached from the top portion and melted away. 

 

Northwestern Glacier in 1909 and 2011

A black and white photo.  The bottom half of the picture is water. In the center of the image is a glacier.  On the left and right of hte glacier are rocky outcroppings.  In the background are snow covered mountains A black and white photo.  The bottom half of the picture is water. In the center of the image is a glacier.  On the left and right of hte glacier are rocky outcroppings.  In the background are snow covered mountains

Left image
Northwestern Glacier in Northwestern Fiord.  Photo taken in 1909
Credit: USGS/ U.S. Grant

Right image
Northwestern Glacier. Photo taken in 2011
Credit: NPS Photo/ D. Kurtz

In 1909 U.S. Grant was a field geologist for the USGS for the summer and was also professor and chair of the Northwestern University geology department at the time. Grant decided to honor his alma mater by naming this incredible glacier after it. Northwestern has retreated at least 6 miles since then and has revealed a spectacular fjord with sweeping granite faces and terrain that is unique in the park. The current terminus of Northwestern glacier cannot be seen in this photo, although it is still a tidewater glacier for now. Ogive glacier, which once was one of many glaciers that fed into Northwestern glacier, is seen center left descending to the water.

 

Northwestern Glacier in 1940 and 2005

A black and white photo.  Chunks of ice are in the foreground of the image.  BEhind them is a thin strip of water, and then the face of a glacier.  There are snow covered mountains on behind the glacier A black and white photo.  Chunks of ice are in the foreground of the image.  BEhind them is a thin strip of water, and then the face of a glacier.  There are snow covered mountains on behind the glacier

Left image
Northwestern Glacier in Northwestern Fiord. Photo taken in 1940
Credit: NPS Photo

Right image
Northwestern Glacier, photo taken in 2005
Credit: USGS Photo/ B Molnia

Northwestern Fiord looked quite different in 1940 to how it does today. Notice the thickness of the ice that once nearly covered the steep ridge seen in the distance (center left) of the repeat photo. Beyond that ridge you can see the hanging glaciers that are close to the present tidewater terminus of Northwestern glacier more than 6 miles away.  Can you imagine traveling through these waters and trying to envision the movement of such a titanic force?

 

Northwestern Glacier in 1990 and 2020

A blueish colored glacier flows from the top center of the image to the bottom center.  Two rocky mountains are on the left of the glacier, and one rounded mountainside is on the right of the glacier.  The bottom third of the image is icy water. A blueish colored glacier flows from the top center of the image to the bottom center.  Two rocky mountains are on the left of the glacier, and one rounded mountainside is on the right of the glacier.  The bottom third of the image is icy water.

Left image
Northwestern Glacier in Northwestern Fiord. Photo taken in 1990
Credit: NPS Photo/M Tetreau

Right image
Northwestern Glacier, photo taken in 2020
Credit: NPS Photo/ E Kulack

Northwestern Glacier is a tidewater glacier in Northwestern Fiord, although the right portion has retreated onto bedrock. This is the same glacier seen in the other photos on this page from 1909 and 1940, just at its current terminus.

 

Southwestern Glacier in 1990 and 2021

The bottom half of the image is water with chunks of floating ice in it. The top half of the image is mountains with snow patches. In the center of the image a glacier flows from right of center to cent, and down to the water. The bottom half of the image is water with chunks of floating ice in it. The top half of the image is mountains with snow patches. In the center of the image a glacier flows from right of center to cent, and down to the water.

Left image
Southwestern Glacier in located Northwestern Fiord.  Photo taken in 1990
Credit: NPS Photo/M Tetreau

Right image
Southwestern Glacier, photo taken in 2021
Credit: NPS Photo/ H Beutler

Southwestern Glacier is a land terminating glacier with a small proglacial lake in Northwestern Fiord. In the original photo, notice the glaciers once converging into this area and the substantial thinning and retreat since then. The debris covered portions of the glacier are from medial moraines and landslide material where the glaciers converge and flow together.

 

Anchor Glacier in 1991 and 2021

A blue colored glacier flows over a mountainside.  Center right is a large rocky outcropping from undre thglacier. A blue colored glacier flows over a mountainside.  Center right is a large rocky outcropping from undre thglacier.

Left image
Anchor Glacier in Northwestern Fiord. Photo taken in 1991
Credit: NPS Photo/M Tetreau

Right image
Anchor Glacier, photo taken in 2021
Credit: NPS Photo/ H Beutler

Anchor glacier is in Northwestern Fiord, and the changes here are much more subtle to see. Note in the 2019 repeat photo that a large calving event occurred right before the photo was taken at center right of the terminus. There you can see the large patch of fresh white ice. Although it’s difficult to tell in the photo, Anchor is no longer a tidewater glacier. There are a few variables that make repeat photography from a boat challenging such as sea state, tide, wind, the height of the deck from where you’re taking the photo compared to the original, or GPS accuracy that may affect how it lines up. For example, we now know the location of where this 2019 photo was taken needs to move to the lookers right to better align with the original photo. Aligning features in the field can be tricky and more difficult than it looks.

 

Ogive Glacier in 1991 and 2019

The bottom fifthof the picture is water.  A blue colored glacier flows over a mountain at the top of the picture, and down to the water.  The glacier is narrow in the middle of the image as it flows between two rocky outcroppings. The bottom fifthof the picture is water.  A blue colored glacier flows over a mountain at the top of the picture, and down to the water.  The glacier is narrow in the middle of the image as it flows between two rocky outcroppings.

Left image
Ogive Glacier in Northwestern Fiord. Photo taken in 1991
Credit: NPS Photo/M Tetreau

Right image
Ogive Glacier, photo taken in 2019
Credit: NPS Photo/ E Kulack

Ogive glacier is named after a glacial term for its alternating dark and light arched bands flowing down the glacier. They are more difficult to see now as the glacier has thinned and more sediment has accumulated on its surface. As defined by the National Snow & Ice Data Center, ogives are bands that form on some glaciers just below icefalls. The bands alternate in both height and color, and result from seasonal patterns. Darker bands form through increased melt and refreezing in the summer, when sediment collects on the glacier surface. Lighter bands form in cooler months, when snow accumulates and traps tiny air bubbles. Because the ice flows faster down the center of the glacier, where it has less friction with surrounding bedrock, the ogives are shaped into arcs that point towards the end of the glacier.

 

Sunrise Glacier in 1990 and 2020

A large mountain is in the center of the image. An alpine glacier flows from the upper left of the mountain down towards the center.  The bottom third of the image is water with ice chunks floating in it. A large mountain is in the center of the image. An alpine glacier flows from the upper left of the mountain down towards the center.  The bottom third of the image is water with ice chunks floating in it.

Left image
Sunrise Glacier in Northwestern Fiord. Photo taken in 1990
Credit: NPS Photo/M Tetreau

Right image
Sunrise Glacier, photo taken in 2020
Credit: NPS Photo/ E Kulack

Sunrise Glacier is a debris covered alpine glacier in Northwestern Fiord. The debris that covers the lower portion of the glacier is mostly landslide material that insulates the ice underneath it, slowing its melt and retreat. However, you can see the non-debris covered portions have retreated and thinned over time.

 

Repeat Photography Collection in Kenai Fjords

This collection of photos is part of an ongoing repeat photography project documenting coastal glacier change in Kenai Fjords National Park in southcentral Alaska. The oldest photos in the collection were taken in the summer of 1909 when USGS surveyors, U.S. Grant and D.F. Higgins, completed a detailed survey of the tidewater glaciers along the southeastern coast of the Kenai Peninsula. Nearly 100 years later, in 2004 and 2005, USGS Geologist, Dr. Bruce Molnia, (with assistance from Park employee, Jim Pfeiffenberger) identified the locations of the photo sites and repeated the photos, providing a 94-year comparison of change at individual glaciers.

In the early 1990s, Park natural resources staff, Mike Tetreau and Bud Rice, developed a new catalog of glacier photos and metadata. Most of these photos are taken from boat-based photo point locations. The original slides from this dataset are archived in the park’s collections.

In 2011, Park Physical Scientist, Deb Kurtz, discovered and merged the two photo collections. She also developed metadata for the Grant/Higgins-Molnia dataset and set out to replicate every photo in the comprehensive collection.

There are many challenges in accurately replicating and aligning photos taken from boats due to variable positioning influenced by currents, winds, tides, and the height of the boat itself. Despite the challenges, the resulting photo sets effectively document the changing landscape. Several glaciers exhibited remarkable change in the recent past, which inspired an effort to annually photo-document the more accessible glaciers, and to repeat all photos every few years when possible. As of 2020, most of the park’s glaciers continue to shrink, and the repeat photo collection continues to grow. The collection currently consists of 77 sets of photos, including 265 photos of 40 individual glaciers or glacier groups. This collection documents the current but ephemeral state of the park’s changing glaciers and provides a historical record for all.

Last updated: September 29, 2021

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