PhD Theses at SCIENCE – University of Copenhagen

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

Publication: ResearchPh.D. thesis

A warming climate affects the entire planet, but the Arctic experience a warming that is
faster than elsewhere in the world. This influences several processes affecting the
evolution of the Arctic coast, and increasing erosion rates are detected throughout large
parts of these high-latitude coasts. The warming air temperature affects the soil
temperature and permafrost thaws and destabilizes the material in the coastal zone. In
Greenland, the warming temperature lowers the surface mass balance of the Greenland Ice
Sheet and more material is transported to the coastal zone. The sea ice extent is thinning
and diminishing and prolongs the open water period and thereby the period where waves
can affect the coast. Only limited work has focused on coastal areas in Greenland and the
current knowledge on these areas is sparse.
Coastal morphology of Greenland is highly variable spanning from rocky coasts and
archipelagos to sandy beaches, marshes and deltas. This PhD thesis investigates coastal
evolution with a special focus on changes in deltaic environments both during the Holocene
and in a modern changing climate. The first part of the thesis (Paper 1 and 2) focus on
detailed processes affecting delta evolution at in West and Northeast Greenland, while the
second part (Paper 3) focus on decadal evolution of a vast majority of the deltas stretching
from west, down the southern tip to the central eastern part of Greenland. Two delta types
are identified, where one is a restricted delta often located in the bottom of a fjord and the
second type is a wider fan-shaped open delta. Most deltas are directly coupled to the
Greenland Ice Sheet or local icecaps and are highly influenced by the dynamics in the
catchments. It is demonstrated how a modern changing climate directly affects delta
dynamics, and that Greenlandic deltas are prograding, contrary to the global trend showing
eroding Arctic coasts. Moreover, it is revealed that the increasing proglacial freshwater
runoff, caused by a lowering of the surface mass balance of the Greenland Ice Sheet is the
main determining agent in delta progradation. The final part of the thesis (Paper 4) focuses
on beach ridges located in deltaic environments. Using ground-penetrating radar it is
shown, that these coastal features constitute a solid base for reconstruction of changes in
past sea-level variation in Greenland.
Original languageEnglish
PublisherDepartment of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen
StatePublished - 2017

ID: 181259725