This project funded by Research Council of Norway through the NARE (Norwegian Antarctic Research Expedition) programme carrys out comprehensive sets of investigations on grounded ice isles (ice rises) in the Fimbul ice shelf vicinity, western Dronning Maud Land. The primary goal of this project is to elucidate the mass-balance history of the Fimbul ice shelf vicinity over the past several millennia. Ice shelves like Fimbul are intrinsically sensitive to changes in the ocean due to direct access of warm water from proximal abyssal plains. The secondary goal is to decipher ice-flow dynamics of the inter-connected system of ice rises, shelf ice, and outlet glaciers. A better understanding of ice-flow dynamics has been identified by the Intergovernmental Panel on Climate Change as being critical for predicting future Antarctic mass balance and hence sea-level rise. Our results will be used to decipher the impacts of future ocean changes on the mass balance in the Antarctic coastal area.

Dronning Maud Land coast is a complicated inter-connected system of ice rises, shelf ice, and outlet glaciers

Ice rises proposed to study in this project (labeled A-E). See the figure above for the coverage of this map. Background is MODIS satellite images, and color of circles shows the elevation of seafloor in meters below sea level. Cross markers show the sites of oceanographic and glaciological surveys for the ongoing NARE project on Fimbul ice shelf. Blue curves highlight the edge of the floating ice. Red and green curves show traverse routes established by NARE and South African National Antarctic Program (SANAP).

Satellite view of Dronning Maud Land. The inset shows the coverage of the main map (dotted square) together with ice shelves (gray) and continental shelf (black).

The Antarctic ice does not flow uniformly.  There are many “rivers of ice”, called ice streams or fast-flowing glaciers.  These in Dronning Maud Land originate near inland nunataks, which locate about 200 km inland from the current grounding zone where ice becomes afloat.  Dynamics of these rivers is critical to better assess mass of the Antarctic ice sheet and predict its future, which is essential to predict future contribution of the Antarctic ice sheet to the global sea-level change.

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Ice flows on a range of beds.  The softest bed is “water”, which provides no basal drag to the ice motion.  It is found over subglacial lakes and over ocean (ice shelf).  The hardest bed is probably “hard rock frozen to the ice”.  Between is the “sediments” and the glaciers sitting on it is called “soft bedded”.  Breidamarkjokull is well known as the glacier at which paradigm shift happens in glaciology during 1980s.  Together with other evidence from West Antarctica, glaciologists changed their understanding about ice flow dramatically. Read the rest of this entry »

Cake representation of subglacial lake Vostok

Have you heard “subglacial lakes”? Ice has low heat conductivity so it works as a blanket to prevent penetration of the cold wave from the ice-sheet surface to bed. Most part of Antarctica is likely geothermally inactive, but still efficient blanket and some geothermal heating are good enough to melt the ice-sheet bottom. Nowadays, more than 170 lakes are inventoried and the largest one “Subglacial Lake Vostok” in East Antarctica is our research target. Read the rest of this entry »

Let’s think how scientists estimate the past evolution of the ice sheet.  When ice flows, ice scratches rocks and deposit sediments.  Such features are distinct from geomorphologic features made by rivers, winds and so on.  Rock/sediment samples from the surface can even tell how old it is.  Okey, when we can find such “geological evidence” of the ice sheet evolution, it is a job for geologists.  If the region is still covered by ice, geologists have no jobs (it is unrealistic to melt all ice, right?).  Glaciologists do the job. Read the rest of this entry »