By combining photographs from the 1930s with more recent images and satellite data, a Norwegian research team has determined that some of the glaciers in East Antarctica have been fairly stable over the last hundred years.
The year is 1937, east of Antarctica. A Stinson Reliant, equipped with an automatic camera, flies over a coast covered in thick ice and photographs glaciers. The expedition, commissioned and paid for by Norwegian whaler Lars Christensen, was the first large-scale aerial photography campaign to be carried out on the Antarctic continent. The aim is to map this part of the continent, which is much less explored than the western part.
With its mission completed, the expedition returned to Norway, in the midst of a troubled Europe. War broke out soon afterwards and Norway was invaded by Nazi Germany, putting an end to the map project. The Norwegian Polar Institute in Tromsø stored the images in its archives, where they were forgotten for almost a century before researchers at the University of Copenhagen uncovered the expedition’s story. They then travel to Tromsø, where they review the 2 200 aerial views taken during the expedition and select 130 for analysis.
A real windfall. There are very few old images of glaciers in East Antarctica, which poses a real problem: how can we track the evolution of glaciers without images or data? “In Greenland and Svalbard, long-term observations from historical aerial images have been vital for determining the historical response of glaciers to climate change.”, note the authors in their study published May 25 in Nature Communications. “However, in Antarctica, the scarcity of historical climate data makes climate reanalysis estimates before the 1970s largely uncertain, and observed trends cannot clearly be distinguished from natural variability.”
The archival images will be supplemented by 164 images of the same glaciers taken by Australian scientists between 1950 and 1974 and combined with modern satellite data, providing composite 3D images of glaciers over some 2 000 kilometers of coastline, and some rather encouraging conclusions. The results show that glaciers in East Antarctica have remained stable over the last 85 years. Good news according to Mads Dømgaard, lead author of the study: “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 the PhD student in a press release issued on May 30 by the University of Copenhagen.
However, changes are already visible in the sea ice. “Our results also indicate weakening sea ice conditions, making the glaciers’ floating ice tongues more vulnerable and unable to grow as large as seen in the early aerial images from 1937. We know from other parts of Antarctica that the ocean plays an extremely important role and drives the massive and increasing melt we see in e.g. West Antarctica,” says Mads Dømgaard.
Mirjana Binggeli, Polar Journal AG
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