Researchers at the University of Copenhagen have gained an unprecedented understanding of the ice evolution in East Antarctica, thanks to a trove of forgotten aerial photographs taken by a Norwegian whaler in 1937. By comparing these historical images with modern satellite data, the scientists found that the glaciers have remained stable and even grown slightly over nearly a century, although they observed early signs of weakening. The findings, published in Nature Communications, provide valuable insights that improve predictions of ice changes and sea level rise.
The study focused on an area covering approximately 2,000 kilometers of East Antarctic coastline, containing an amount of ice equivalent to the entire Greenland Ice Sheet. Using hundreds of old aerial photographs combined with modern computer technology, the researchers tracked the evolution of these glaciers over time.
Stable Glaciers, but Weakening Sea Ice
The study revealed that the East Antarctic glaciers have not only remained stable but have grown slightly over the last 85 years, partly due to increasing snowfall. This finding offers a glimmer of hope amidst the constant barrage of news about climate change and melting ice.
“We constantly hear about climate change and new melt records, so it’s refreshing to observe an area of glaciers that has remained stable for almost a century,” says PhD student Mads Dømgaard, the study’s first author.
However, the researchers also observed the first signs of changes in the sea ice off the glaciers, which could lead to the shrinking of these stable East Antarctic glaciers in the future. The weakening sea ice conditions make the glaciers’ floating ice tongues more vulnerable and unable to grow as large as seen in the early aerial images from 1937.
Forgotten Images Provide Critical Knowledge
Most of the images used in the study were captured during a 1937 expedition organized and paid for 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 had been stored at the Norwegian Polar Institute in Tromsø and forgotten until the University of Copenhagen researchers discovered their existence.
“By comparing the historical aerial photos with modern satellite data, we have gained critical knowledge about glaciers that we would not otherwise have had. I think it’s fantastic that these old images can be used to generated new research results almost 100 years after they were taken,” says Assistant Professor Anders Bjørk from the University of Copenhagen, who leads the group working with the historical images.
The researchers emphasized the importance of solid, long-term data for producing accurate predictions of future glacier evolution and sea level rise. The study provides new insights into a vast area in East Antarctica, improving the ability to create more accurate models of future ice changes.
The results are a collaboration between researchers from the University of Copenhagen, the Norwegian Polar Institute, the Arctic University of Norway, and the Institute of Environmental Geosciences in France.