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The influence of Earth-surface processes on solid-Earth, ice-sheet, and sea-level interactions for Scandinavian Ice-Sheet collapse

Periodic Reporting for period 1 - EROSIVE (The influence of Earth-surface processes on solid-Earth, ice-sheet, and sea-level interactions for Scandinavian Ice-Sheet collapse)

Reporting period: 2018-08-01 to 2020-07-31

One of the grand challenges for society in the future will be to cope with the consequences of a changing climate and resulting changes in global sea level. Yet, predictions of past and future scenarios are associated with significant uncertainties, as we do not currently understand all processes that influence ice-sheet variability and thereby global ice volume. One key shortcoming relates to Earth-surface processes. Fjord formation by selective glacial erosion has the potential to elevate surrounding regions significantly by erosional unloading (~1 km in Greenland). However, the consequences for ice-sheet dynamics and global sea level have never been explored.

Within the framework of this project will i) constrain solid-Earth deformation and global sea-level changes due to Quaternary erosion and deposition in the Scandinavian region, ii) assess the influence of long-term glacial erosion for SIS dynamics, ice volume, and sea-level contributions, and iii) gain significant insight into important interactions between surface processes, solid-Earth deformation, ice-sheet variability and sea-level changes, and improve our understanding of SIS collapse.
The approach taken in this project is to combine quantitative analyses and state-of-the-art numerical modelling efforts from the two disciplines of sea-level research and glacial geomorphology with empirical data analysis, in order to investigate the influence of such processes on the solid Earth, ice sheets, and sea level. This novel modelling scheme will be applied to study the former Scandinavian Ice Sheet (SIS), where remarkable empirical constraints exist on glacial isostatic rebound, past ice sheet extent, and deposited sediment volumes. By investigating a former ice sheet, this project will improve our understanding of processes that are highly relevant for the future evolution of existing ice sheets such as the Greenland ice sheet.

This project has found that erosion and deposition during glacial times has a significant impact on solid Earth deformation and local sea level, both in Scandinavia and in Greenland. In particular, the selective glacial erosion that form deep valleys and fjords will result in surface changes that extend far beyond the glacial troughs and the onshore region in general. As a result, the coastline regions on fjord-dominated areas may have experiences as much as several hundred meters of relative sea level fall during glacial times. The project has also found that ice sheets are widely affected by changes in the underlying topography. By changing the the amount of ice that can be stored on land, landscape evolution has the potential to influence global sea level. Finally, the work from this project is expected to improve the general understanding of landscape evolution in Scandinavia during glacial times, in particular related to the effects of erosion-induced solid-Earth deformation and the effects glaciations have had in the region.
Understanding important interactions between surface processes, solid-Earth deformation, ice-sheet variability and sea-level changes, will improve our overall understanding of our dynamic Earth and also the scientific basis for decision makers to shape well-founded policies for optimal adaptation to future sea-level changes.
Fieldwork in Lysefjorden region, Norway