Saline Permafrost in Arctic Coastal Environments: Effects of Post-Glacial Isostasy and Climate Change (SPACE EPIC)

• Applicant: Dr. Michael Angelopoulos
• Subject Area: Physical Geography ; Geology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 533950637

Permafrost is not necessarily frozen, because salts in the sediment pore space depress the freezing point below 0 °C. Saline permafrost, one of the least understood features of the cryosphere, is primarily found in marine deposits beneath shallow shelf seas and are often extends kilometers inland from present Arctic coastlines where most infrastructure lies. On land, widespread saline permafrost formed due to post-glacial rebound exceeding sea level rise, which exposes subsea sediment to the atmosphere. Frozen saline permafrost has a lower freezing point than permafrost containing fresh porewater, making it even more susceptible to thawing as the Arctic heats up. Consequently, saline permafrost is a hazard for infrastructure because of potential surface subsidence and reduced load-bearing capacity of sediment. Further, warming saline permafrost creates cryopegs (i.e. unfrozen saline permafrost pockets/layers), where greenhouse gases can accumulate and migrate through permafrost. To evaluate the large-scale impact of saline permafrost in the Arctic, I aim to research how post-glacial isostasy and climate influence its development. I hypothesize the following: 1) As sub-aerial exposure time increases, salts in the marine sediments diffuse to greater depths, increasing the probability of cryopeg occurrence; 2) Climate warming will trigger cryopeg initiation or expansion in saline permafrost. My project has two main goals: 1) Generate geophysical 2D/3D insights showing how the depth, thickness, and salinity of marine permafrost sediments change with sub-aerial exposure time for different terrain classes (land, lagoons, and lakes) near Ny-Ålesund on Svalbard; 2) Quantify how sensitive saline permafrost and the depth and size of cryopegs are to climate warming. The area near Ny-Ålesund is ideal for my project, because the post-glacial rebound history is known and the sub-aerial exposure time can be estimated. My research will explore saline permafrost at different stages of development by performing a 2.5 km electrical resistivity tomography (ERT) profile starting at the shoreline and intersecting raised beach terraces. Shallow permafrost cores (30 cm) will be extracted along the profile for hydro-chemical analysis and ERT calibration. The CryoGrid numerical modeling suite will be adapted for high-salinity conditions to simulate how varying geological and climate conditions control saline permafrost evolution and potential cryopeg initiation or expansion on Svalbard. My research will provide new insights on salt transport in the cryosphere, which represents a significant gap in our understanding of permafrost. By benchmarking a numerical model with ERT and hydro-chemical data from Svalbard, we can better anticipate Arctic saline permafrost degradation in the coming decades on a larger scale.

• DFG Programme: Research Grants