The Shape of a Glacier Influences Its Vulnerability to Melting

A new study funded by NASA found out that a glacier’s shape plays a huge role in predicting how it will melt. Through this study, scientists have discovered how glaciers found in the West Greenland will melt. The research will help scientists predict next century rise in future seal levels due to the Ice Sheet found in Greenland. The current rise is being measured in inches and in some places, in feet.

Denis Felikson, the study’s lead author, who completed his PhD from the “Department of Aerospace Engineering and Engineering Mechanics” at University of Texas and is working as a research assistant at Institute for Geophysics (UTIG) said that through this study, he was able to identify threatening glaciers that were usually dismissed. His study can be found in the “Nature Geoscience” journal.

According to recent findings by scientists, glaciers that are losing mass are linked to climate change. The Ice Sheet in Greenland is known as the earth’s second largest sheet, which has been losing its shape for decades. One thing the scientists are sure about is that climate change will vary if individual coastal glaciers separate themselves from the large ice sheet and float in the ocean. Due to this, it can become difficult to predict any future changes in the sea level.

According to Felikson, they have found a unique way to explain the reason behind this variability. In the research, sixteen glaciers were investigated, out of which, four were found susceptible to melting: Sermeq Silardleq, Rink Isbrae, Jakobshavn Isbrae and Umiamako Isbrae.

Jakobshavn Isbrae, Umiamako Isbrae and Sermeq Silardleq are already melting. Amongst these three, Jakobshavn Isbrae is responsible for above 81% of total mass loss in Greenland’s ice sheet over the past three decades.

As for Rink Isbrae, since 1985, it has remained stabled but is predicted to lose its terminus (the glacier’s front that is exposed to water) and become unstable. The director of the Cryosphere Program headed by NASA, Tom Wagner said that for years, they had no idea about the ice, which was melting in Greenland but now, they are trying to discover any critical details, which will lead them to the way on how to control the glaciers’ behaviors.

To find about the glacier’s susceptibility to melting, their inland thinning is calculated from the terminus. Other details such as its surface slope, how it is influenced by its position on land and thickness also play an important role in the calculations. According to researchers, glaciers that are flat and thick, thin faster as compared to those that are steep and thin.

Most glaciers reach the far inland from 16 to 48 kilometres. However, in the case of Jakobshavn Isbrae, the risk of inland thinning is more than 240 kilometres. This amounts to Greenland’s one third of the ice sheet. The reason why Jakobshavn Isbrae is so vulnerable to thinning is because its path extends to a deep trough, leading into the interior of the ice sheet.

Though the method used by Felikson will identify which glaciers are melting, it will not provide calculations about how much mass the glaciers will lose. Timothy Bartholomaus, the study’s co-author believes that the analysis will help them take better calculations in the future.

By collecting data from the “Ocean Melting Greenland” project by NASA, Felikson’s team used a topography map of bedrock to create a model based on digital elevation and determine the glaciers’ thickness. Measurements were taken from an instrument known as “Advanced Spaceborne Thermal Emission and Reflection Radiometer” (ASTER), which was provided by Japanese.

UTIG’s research associate and a professor at Jackson School of Geosciences, Ginny Catania said that they plan to apply same techniques to all glaciers around the world, especially in Antarctica.

Researchers who collaborated in the study include University of Copenhagen, University of Kansas, Oregon State University, University of California, University of Oregon and Department of Earth Sciences from Iceland Institute.