Being the first site in Greenland and one of the first in the whole Arctic region in general, the Ilulissat Icefjord was declared a UNESCO World Heritage Site in 2004 because of its unique glaciology and natural beauty.
The spectecular icebergs which float in the fjord, find their way from the inland ice down the large outlet glacier Sermeq Kujalleq (Jakobshavn glacier), which is one of the fastest moving glaciers of the world and is certainly known to be the most productive glacier in Greenland.
Besides its stunning landscapes and its exceptional glaciology, the World Heritage site contains one of the oldest Inuit settlement ruins, Sermermiut, the most important cultural site in Greenland. Situated at the opening of the fjord there is an archaeological area, where the settler first arrived, approx. 4,500 years ago.
It is the rich and diverse marine fauna of the ice fjord, which made it possible that three different cultures could settle in the area until the present-day civilisation found its way here.
Looking at Greenland’s topography, one will see the bedrock forming a bowl shape, which lies especially in the northern part mainly approximately 150 m below sea level.
The south of Greenland consists of a lightly corrugated highland which is segmented by numerous fjords, bays, straits and narrows. At the edge of the highland, some high rising mountain ranges line up at the east coast, finding their highest altitude at the 3,694 m high Gunnbjørn Fjeld in the midst of the Watkins mountains, which also is called Hvítserk.
The north east is bordered by mountain ranges of the caledonian fold belt as well as the Ellesmere fold belt in the north, which both surround the deep trenched mainland basin reaching down to 150 m below sea level, while the west finds much lower elevations.
The exception in the west of Greenland is the mountains on the edge of Disko Bay, through whose flanks one of Greenland’s most impressive canyon systems stretches all its way down to the center of the island.
This canyon system is much over the the Greenland Ice Sheet. That means these gorges were formed by rivers even before Greenland glaciated. The size of this canyon system is impressive at around 450,000 km2 and represents 20% of the entire land mass of Greenland (incl. islands).
This makes this canyon comparable to the size of Ohio River, which is the largest tributary of the Mississippi – or roughly twice the size of the UK. The gorge has a relative depth of about 1,400 m and a width of up to 12 km.
One of these gorges is now covered by the Sermeq Kujalleq glacier (Jakobshavn glacier).
Sermeq Kujalleq is one of the great valley glaciers in West Greenland. Its catchment area is equivalent to about 7% of the Greenland Ice Sheet (comparable to up to 110,000 km2) and pours more ice into the oceans than all of the northern hemisphere glaciers.
The ice stream appears as a narrow 3-6 km wide, well-defined channel extending from the present glacier front to the ice cover for up to 80-85 km. There, at heights of 1,350 to 1,400 m, he loses his own identity and divides into three subsections, which gradually disappear into the surface topography of the surrounding ice cover.
The calving front protrudes a little over 100 m out of the water while the glacier is up to date an estimated thickness of about 1,200 m at the front. The mass of icebergs that separate each year from this front adds up to 35 billion tons. The icebergs can often be up to 1 km in size. Thus they are too big to drive easily through the fjord, which is about 800 m deep on average (at its lowest point 1 km).
At its sea-side end, approximately 225 meters below sea level, there is a morainic deposit where the larger icebergs are trapped under water. This is the reason for the accumulation of huge icebergs at this point, which dammed the broken ice in the fjord, giving it its name Icefjord. To reach the sea-side end of the fjord, the icebergs need about 12 to 15 months. The glacier estimates that it accounts for about 10% of the amount of water that Greenland discharges into the sea.
At the exit of the fjord, a moraine deposit of gravel and stone forms a relatively flat arched threshold extending from Sermermiut in the north to Avannarliit in the south.
This so-called iceberg bank is shaped and changed in its structure over and over again by the icebergs that pile up on it. The small depth of 200-250 m suggests that the iceberg bank represents the western end of the ice fjord. It separates the up to 1 km deep ice fjord from the maximum 400 m deep Disko Bay.
Throughout the year, larger icebergs are stranded on this bank, blocking the exit of the fjord. The thus accumulated smaller icebergs eventually form the current ice fjord.
The large icebergs remain on the sandbar until they are either so molten that they break up into smaller pieces or make it over the sandbar, or until the pressure inside the fjord is so great that the ice in the fjord interior the icebergs over the sandback presses.
The ice fjord itself is about 70 km long and is packed with icebergs and ice floes, which are slowly pushed through the whole ice fjord. The icebergs are between 3 and 15 months in the ice fjord on the way.
Since the first survey of the course of the glacier front in 1850, it has been retreating steadily westward. A temporary highlight was the decline in the 1950s. At that time, the glacier could grow again in the winter months and only partially melted in the summer.
After several decades of relative stability, the glacier’s flow rate has increased dramatically since the late 1990s, while the glacier’s floating tongue has lost more and more of its power and disintegrated.
The continuously increasing flow rate at the end of the glacier in recent years increasingly influences the higher areas of the glacier, which also lose their power. The speed of the retreat accelerated again at the turn of the millennium, retreating about the same distance as in the 100 years before.
In the wake of the global glacial meltdown as a result of global warming in the Arctic, Sermeq Kujalleq released so much ice to the sea between 2000 and 2010 that it alone caused a sea-level rise of one millimeter.
Since 2012, a further acceleration of the flow rate has been recorded, which has now quadrupled compared to 1990 and reaches a flow speed of 17 km per year. He is thus considered the permanently fastest flowing ice flow in the world. The frontline is now over deeper waters in the back of the fjord, where the water depth is about 1,300 m.
The researchers believe that the deeper water increases the glacier’s flow rate. The deeper water would cause more icebergs to break off, causing the glacier to add more ice.
In addition, recent measurements have shown that the glacier has a thickness of up to 1,500 m. This would mean that the resulting greater depth of the glacier bed has a thicker front line than today, which is attacked by the warm sea water, resulting in an even stronger melting. On the other hand, a pressure arises at this thickness, which significantly reduces the pressure melting point, which further accelerates the flow velocity of the glacier.
Investigations have found different flow velocities in different areas of the glacier. The small mountains in the center mean that significantly higher velocities develop in the north and south depressions and, in turn, a higher velocity in the southern part. This is where the fjord will fork. At least since 2005, we have been able to observe this development very clearly on the decline of the glacier front.
Sermeq Kujalleq and thus the ice fjord are considered as one of the most important indicators for climate change. Nowhere else in the Western world is this as tangible and vividly experienced as here.
Due to the retreat of the Sermeq Kujalleq glacier at the end of the ice fjord, the Ilulissat Icefjord has become a symbol of the effect of global climate change. We have extensive knowledge of the glacier, which is scientifically one of the most supervised glaciers in the world.
From 1850 to date, data has been collected showing that the position of the glacier front has always changed as a result of climate change over time. 4,000-5,000 years ago, the glacier even stood on the spot where it now stands.
Understanding the dynamics of the Greenland ice sheet still has serious gaps. In recent years, however, it has become clear that the ice sheet in Greenland is losing ground due to climate changes. The Greenland ice sheet is considered to be the “awakening giant” and the increased release of meltwater from this ice sheet can significantly increase the predicted global sea level over the next century and have a strong local impact on the socio-economic development of Greenland.
Close monitoring of the mass balance of the ice sheet but also of the large outlet glaciers, such as the Sermeq Kujalleq, as well as coupled climate and ice sheet forecasts are urgently needed to make better forecasts.
However, it is difficult to determine to what extent humans have caused climate change in the Ilulissat Icefjord.
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