Animations that compress more than two decades of satellite images into one second reveal the complex behavior and flow of glaciers in the Karakoram mountain range in Asia. The animations, created by University of Zurich scientist Dr Frank Paul, were published today in the journal Cryosphere.

Glaciers are large bodies of ice that can be found near the Poles and in some mountainous regions. They are formed when snow falls, freezes and gets compressed.

The weight of the ice forces the glacier to flow. As they move very slowly, the best way to study how they move and change is by looking at glaciers from above and over long time periods.

Dr Paul has come up with a novel method that allows scientists to easily see glacier movements and changes.

He used images from 1990 to 2015 captured by three NASA/USGS Landsat satellites to create timelapse sequences of four regions in the Karakoram mountain range: Baltoro, Panmah, Skamri–Sarpo Laggo and Shaksgam.

This range is home to some of the highest peaks in the world, including the famous K2, and glaciers of varying sizes cover much of the steep and high terrain. They show complex behavior – most of them are not retreating, unlike in other regions in the world, but are advancing or surging and flowing into each other.

Twenty five years of slow glacier change are compressed into one second, meaning glacier movement is sped up some 800 million times.

“The most interesting insight is to really see how the glaciers flow and how the individual parts of the glaciers such as the tributary streams interact,” Dr Paul said.

The animations show that they are not actually retreating, but are advancing or surging and flowing into each other.

“From a scientific point of view, the key motivation for this research was to understand the highly variable behavior of the glaciers in the Karakoram,” Dr Paul said.

“We have known about this for over 50 years, but still have a very limited scientific understanding of what is going on there,” the scientist said.

“The animations are a very practical way to get a better overview and follow the changes through time,” he added.

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F. Paul et al. 2015. Revealing glacier flow and surge dynamics from animated satellite image sequences: examples from the Karakoram. Cryosphere 9, 2201-2214; doi: 10.5194/tc-9-2201-2015