Numerical simulations provide a way to link the melt at the glacier surface to the hydrology system at the glacier bed to explain the surge in Basin 3, Austfonna Ice-cap, Svalbard. This is shown in a fresh doctoral thesis on ice flow modeling of ice shelves and ice caps by Yongmei Gong.

Predictions of the contribution of glaciers and ice sheets to global sea level rise appear on social media, and are of great interest broadly; originally the predictions are taken from scientific publications such as the IPCC assessment report, which are based on the calculations from computer models.

“The predictions, however, have large uncertainties because of the assumptions we made when doing those calculations”, says Yongmei Gong, defending her doctoral thesis for the University of Helsinki on February the 13th.

Ice dynamics

“That is due to the fact that the scientists have not yet fully understood some of the key processes concerning the ice dynamic, for instance the movement of the region where a marine terminating glacier starts to become afloat to form ice shelf and the evolution of the hydrology system at the glacier bed.”

Lambert Glacier-Amery Ice shelf drainage system in East Antarctica will still be stable

According to the research by Yongmei Gong, numerical simulations carried out to predict the future state of the Lambert Glacier – Amery Ice Shelf drainage system, East Antarctica, suggest that the system is going to be rather stable in this century or the next century, even though large amount of melt have been predicted at the base of Amery Ice shelf. The sea level contribution will be no more than 3mm.

Fast flowing Storisstraument glacier pouring ice into the Barents Sea

The glacier in Basin 3, Storisstraument glacier, Austfonna Ice-cap, Svalbard, on the other hand, is flowing much faster now than before. Since 2011 it has been flowing several thousands of meters per year and is pouring ice into the Barents Sea. According to the present research this is related to the input of summer melt water produced at glacier surface to the glacier bed through fractures that penetrates through the full length of the glacier.

“However, we are not sure if the acceleration is due to climate warming”, says Yongmei Gong.

Two different resistant forces of friction

The dynamics of Storisstraument glacier and Amery Ice shelf are governed by two different resistant forces, the friction at the base of the glacier for the former and the friction at the lateral side walls for the latter. These two differences also provide two of the fundamental theory basis for ice flow model development.

 

Yongmei Gong's defence event: https://helsinginyliopisto.etapahtuma.fi/en-us/Kalenteri/English?id=50466#.WnW562luZhE

The thesis “Ice flow modeling of ice shelves and ice caps" is here: https://helda.helsinki.fi/handle/10138/231173

Read more and watch:
https://en.wikipedia.org/wiki/Lambert_Glacier
https://en.wikipedia.org/wiki/Amery_Ice_Shelf

YouTube video Glacier surge: Austfonna, Svalbard, 2011–2016 (satellite image timelapse) from NorskPolarinstitutt showing how fast the glacier in Basin 3 has become since 2011: https://www.youtube.com/watch?annotation_id=annotation_836906983&feature=iv&src_vid=LGckfBq7wiQ&v=38S7VGncI74

Contact information:
Yongmei Gong, Faculty of Science, University of Helsinki, yongmei.gong@helsinki.fi,
tel. +358 50 448 7092

Minna Meriläinen-Tenhu, @MinnaMeriTenhu, minna.merilainen@helsinki.fi, +358 50 415 0316