Researchers at the University of Copenhagen used aerial photos from 1937 to analyze the stability and growth of East Antarctica’s ice, revealing that despite some signs of weakening, the ice remained largely stable for nearly a century, thus improving forecasts of sea level rise. Credit: Norwegian Polar Institute in Tromsø
A study using forgotten aerial photos from a whaling ship from 1937 shows that East Antarctica’s ice remained stable and even grew, despite some early signs of weakening.
Extreme weather, melting glaciers and rising sea levels all indicate that the planet’s climate and ice masses are in a critical state. However, a new study from the Department of Geosciences and Natural Resource Management at the University of Copenhagen reveals a positive anomaly.
Using hundreds of old aerial photographs dating back to 1937, combined with modern computer technology, researchers have tracked the evolution of East Antarctic glaciers. This area, which extends over approximately 2,000 kilometers of coastline, contains as much ice as the entire Greenland ice sheet. By comparing historical aerial photos with modern satellite data, researchers determined the movement and size changes of glaciers, revealing that the ice has not only remained stable, but has also increased slightly over the past 85 years , partly due to increased snowfall.
“We constantly hear about climate change and new melting records, so it is refreshing to observe an area of glaciers that has remained stable for almost a century,” says Mads Dømgaard, doctoral student and first author of the study.
The whaler Firern, with the Stinson Reliant aircraft on board, near Klarius Mikkelsen Fjell in Lars Christensen Land, East Antarctica. Credit Norwegian Polar Institute
First signs of change
Despite the overall stability, the research also reveals the first signs of changes in the sea ice surrounding the glaciers, indicating that these stable East Antarctic glaciers may shrink in the future.
“Our results also indicate a weakening of sea ice conditions, making the floating ice tongues of glaciers more vulnerable and unable to grow as large as the first aerial images from 1937 show. We know, in other regions of Antarctica, that the ocean plays an extremely important role and is the cause of the massive and increasing melting that we observe, for example, in West Antarctica,” explains Dømgaard.
A Poton Stinson Reliant aircraft (call sign LN-BAR) was used for aerial photography. The aircraft had a range of approximately 1,200 km and an automatic Zeiss camera was mounted in the floor of the aircraft. Credit: Norwegian Polar Institute
Hidden from the Nazis
Most of the images used in the study were captured during a 1937 expedition organized and financed by Norwegian whaler Lars Christensen. The mission aimed to produce the first maps of this part of East Antarctica, but the maps were never published due to the German invasion of Norway. The images have since been stored at the Norwegian Polar Institute in Tromsø and forgotten.
When researchers at the University of Copenhagen heard about the expedition, they realized that valuable images were likely hidden in archives in Norway. They traveled to Tromsø and examined the 2,200 images taken during the expedition. They supplemented the Norwegian aerial images with images of the same glaciers from Australian surveys carried out between 1950 and 1974.
“By comparing historical aerial photos with modern satellite data, we have gained essential knowledge about glaciers that we would not have had otherwise. I think it’s fantastic that these old images can be used to generate new research results almost 100 years after they were taken,” says Assistant Professor Anders Bjørk of the University of Copenhagen, who leads the group working on the historical images.
The Honnörbrygga Glacier in the Bay of Lützow-Holm in 1937 compared to a modern Landsat satellite image from 2023. The 9 km long floating ice tongue seen in the 1937 image disappeared in the late 1950s and did not has not grown back due to weakening sea ice. Credit: Mads Dømgaard / Norwegian Polar Institute
Potential for rapid sea level rise
The Antarctic ice sheet is receiving increasing attention from researchers, due to its potential for extremely large and rapid sea level rise. Unlike Greenland, very little was known on Antarctic glaciers until the 1990s, when the first good satellite observations became available.
“Early observations of glaciers are extremely valuable because they give us a unique insight into how the ice has evolved during a variable climate and whether current changes in the ice exceed the normal cycle of advance and retreat of the glaciers,” explains Dømgaard.
Ingrid Christensen, wife of Lars Christensen, participated in several Antarctic expeditions and is considered the first woman to set foot in Antarctica. Here she is seen on the Stinson plane in 1937, ready to launch a Norwegian flag over land in East Antarctica. Credit: Norwegian Polar Institute
Improve predictive models
Robust, long-term data are crucial to producing accurate predictions about future glacier evolution and sea level rise, says researcher, and this study provides new information over a large area of Antarctica Oriental.
“The long glacier time series improves our ability to create more accurate models of future ice changes, because the models are trained on historical observations,” concludes Bjørk.
The results were recently published in 
General map of the expedition route in 1936/1937 and the areas studied by the researchers. Credit: Mads Dømgaard
Learn more about the study
- Of 2,200 images photographed from seaplanes in 1937, 130 were selected for analysis.
- The researchers combined the historical photos with modern satellite data to create 3D reconstructions of the glaciers.
- The Norwegian aerial images were supplemented by 165 aerial images of the same glaciers from Australian surveys carried out between 1950 and 1974. This allowed the researchers to examine the evolution of glaciers over different periods and calculate historical flow velocities ice cream for certain glaciers.
- Compared to modern data, ice flow velocities are unchanged. Although some glaciers thinned over shorter intervening periods of 10 to 20 years, they remained stable or increased slightly over the long term, indicating a system in equilibrium.
Reference: “First photos from aerial expeditions reveal 85 years of glacier growth and stability in East Antarctica” by Mads Dømgaard, Anders Schomacker, Elisabeth Isaksson, Romain Millan, Flora Huiban, Amaury Dehecq, Amanda Fleischer , Geir Moholdt, Jonas K. Andersen and Anders A. Bjørk, May 25, 2024, Natural communications.
DOI: 10.1038/s41467-024-48886-x
The research was funded by the Villum Foundation.