Delta Dynamics:Evolution of Sedimentary Coasts in Greenland in a Changing Climate

• Main Author: Bendixen, Mette
• Format: Book
• Language: English
• Published: Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen 2017
• Subjects: Arctic; Greenland; greenlandic; Ice; Ice Sheet; permafrost; Sea ice
• Online Access: https://curis.ku.dk/portal/da/publications/delta-dynamics(f7399033-67b5-40a2-9eac-349b49f869b2).html; https://soeg.kb.dk/permalink/45KBDK_KGL/fbp0ps/alma99122333604105763

A warming climate affects the entire planet, but the Arctic experience a warming that isfaster than elsewhere in the world. This influences several processes affecting theevolution of the Arctic coast, and increasing erosion rates are detected throughout largeparts of these high-latitude coasts. The warming air temperature affects the soiltemperature and permafrost thaws and destabilizes the material in the coastal zone. InGreenland, the warming temperature lowers the surface mass balance of the Greenland IceSheet and more material is transported to the coastal zone. The sea ice extent is thinningand diminishing and prolongs the open water period and thereby the period where wavescan affect the coast. Only limited work has focused on coastal areas in Greenland and thecurrent knowledge on these areas is sparse.Coastal morphology of Greenland is highly variable spanning from rocky coasts andarchipelagos to sandy beaches, marshes and deltas. This PhD thesis investigates coastalevolution with a special focus on changes in deltaic environments both during the Holoceneand in a modern changing climate. The first part of the thesis (Paper 1 and 2) focus ondetailed processes affecting delta evolution at in West and Northeast Greenland, while thesecond part (Paper 3) focus on decadal evolution of a vast majority of the deltas stretchingfrom west, down the southern tip to the central eastern part of Greenland. Two delta typesare identified, where one is a restricted delta often located in the bottom of a fjord and thesecond type is a wider fan-shaped open delta. Most deltas are directly coupled to theGreenland Ice Sheet or local icecaps and are highly influenced by the dynamics in thecatchments. It is demonstrated how a modern changing climate directly affects deltadynamics, and that Greenlandic deltas are prograding, contrary to the global trend showingeroding Arctic coasts. Moreover, it is revealed that the increasing proglacial freshwaterrunoff, caused by a lowering of the surface mass balance of the Greenland Ice Sheet is themain determining agent in delta progradation. The final part of the thesis (Paper 4) focuseson beach ridges located in deltaic environments. Using ground-penetrating radar it isshown, that these coastal features constitute a solid base for reconstruction of changes inpast sea-level variation in Greenland.