ANTARCTIC MELTING | Not everything is melting in Antarctica: 2,000 kilometers of coast have remained stable for 85 years

ANTARCTIC MELTING | Not everything is melting in Antarctica: 2,000 kilometers of coast have remained stable for 85 years
ANTARCTIC MELTING | Not everything is melting in Antarctica: 2,000 kilometers of coast have remained stable for 85 years



06/18/2024

Act. at 08:11

CEST


Nails forgotten aerial photographs taken in 1937 from a whaler have provided a group of researchers from the University of Copenhagen with the most detailed image to date of the evolution of ice in the Antarctica Oriental.

The results show that The ice has remained stable, and even grown slightly, for almost a centuryalthough scientists observe “early signs of weakening“The research offers new insights that improve predictions of ice changes and sea level rise.

Higher temperatures, extreme weather conditions, melting glaciers and rising sea levels. They are all indicators that The planet’s climate and ice masses are in a critical state. However, this new study, published in ‘Nature Communications’, offers a positive point, at least, on a local level.

Using old aerial photographs dating back to 1937, combined with computer technology, researchers have followed the glacier evolution in East Antarctica. The area covers approximately 2,000 kilometers of coastline and contains as much ice as the entire Greenland ice sheet.

By comparing historical aerial photographs with modern satellite data, researchers were able to determine whether the glaciers have retreated or advanced and whether they have thickened or thinned. The study reveals that The ice has not only remained stable but has grown slightly over the last 85 yearspartly due to increased snowfall.

“We constantly hear (negative information) about climate change and new records of melting, so it is comforting to see an area of ​​glaciers that has remained stable for almost a century,” says Mads Dømgaard, first author of the study.

Hiding from the Nazis

But not everything is positive: the researchers highlight that The study also shows the first signs of changes in the sea ice in front of the glacier. This could mean that stable glaciers in East Antarctica could shrink in the future.

“Our results also indicate a weakening of the conditions of the sea ​​ice, which makes the floating ice tongues of the glaciers more vulnerable and unable to grow as much as seen in the first aerial images of 1937. We know from other areas of Antarctica that The ocean plays an extremely important role and drives the enormous and increasing melting observed, for example, in West Antarctica.“says Dømgaard.

Most of the images used in the study were captured during an expedition organized and paid for in 1936-1937 by Norwegian whaler Lars Christensen. The mission was intended to produce the first maps of this part of East Antarctica, but they were never published due to the German invasion of Norway. The images were hidden from the Nazis and have since been stored at the Norwegian Polar Institute in Tromsø and forgotten.

When researchers read about the expedition, they realized there were probably valuable images hidden away. They traveled to Tromsø and reviewed the 2,200 images taken during the expedition, of which 130 were selected for analysis.

The Norwegian aerial images were complemented by 165 aerial images of the same glaciers from studies carried out between 1950 and 1974. This allowed the researchers to examine the evolution of the glaciers in different periods and calculate historical ice flow velocities for the 21 selected glaciers. .

A system in balance

Compared to modern data, ice flow rates do not change. While some glaciers have thinned over shorter intermediate periods of 10 to 20 years, they have remained stable or grown slightly over the long term, indicating a system in equilibrium.

“By comparing historical aerial photographs with modern satellite data, we have gained fundamental knowledge about glaciers that we would not have otherwise had. It is fantastic that these ancient images can be used to generate new research results almost 100 years after they were taken,” says Anders Bjørk, director of the group that works with the old images.

The Antarctic ice sheet is receiving increasing attention from researchers due to its potential to cause a extremely large and rapid rise in sea level. Unlike Greenland, very little was known about Antarctica’s glaciers until the 1990s, when the first good satellite observations became available.

“The first observations of glaciers are extremely valuable, giving us a unique view of how ice has evolved through a variable climate and whether current changes in ice exceed the normal cycle of glacial advance and retreat.” , explains Dømgaard.

According to the researcher, solid, long-term data is crucial to produce accurate predictions on the future evolution of glaciers and sea level rise, and this study provides new insights into a vast area in East Antarctica.

“Long glacier time series improve our ability to create more accurate models of future ice changes, since the models are based on historical observations,” concludes Bjørk.

Reference report: https://www.nature.com/articles/s41467-024-48886-x

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Contact of the Environment section: [email protected]

 
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