Greenland ice sheet

Greenland ice sheet, with its width of 1,100 km and length of 2,400 km is the second largest ice body in the world after the Antarctic ice sheet. With the total area of 1,710 square kilometers it is nearly 35 times bigger than Slovakia. It is very sensitive to climate change. Caused by the Arctic climate warming, Greenland’s ice sheet has been melting in the last century. In the last decade, the island experienced a vast loss of ice cover. It not just threatens the local people, their traditions and the island’s wildlife, but has a huge impact for the whole world. If the whole ice cover melted, the global sea level would rise of 7 metres and would jeopardise cities like Tokyo, Cairo, Amsterdam, New York or whole countries like Bangladesh or island nations in the Pacific.

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Greenland

Greenland loses an average of 200 cubic kilometres of ice every year. This causes an increase of the sea level by a half millimetre annually, which would be enough to rise the sea level by 5 centimetres in this century. However, the global temperature continues to rise, which supports the speed of the ice sheet loss. A report called Working together with water published by the Dutch Deltacomissione predicts a rapid increase of the sea level caused by Greenland melting by 13 to 22 centimetres till 2100.

The main factor contributing to this process is called glacier calving. This is a process, when the edge of a glacier chunks off. Pieces of ice get to the ocean and melt. Calving is sped up by ocean temperature rise cutting and melting the bottom of the glacier and melt on the top causing lakes on the glacier which drain down many times reaching the bedrock making cracks and rifts through the glacier. This accelerates the movement of the glacier towards the sea.

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Ice calving

The most remarkable calving process can be seen on the Jakobshavn Isbræ glacier, which moves 45 metres a day. Every day, 35 billion tonnes of ice reaches the ocean through this glacier. Between the 1850s and 2010 the glacier retreated by 40 kilometres. The thickness of the Jakobshavn Isbræ glacier decreases, as well. The glacier is thinner by 15 metres, each year. The latest major calving  of Jakobshavn Isbræ glacier was experienced in July and August 2015, when 12,5 square kilometres of ice broke off. The ice is about 1400 metres thick, this equates a volume of 17,5 cubic kilometres. In the last few years, the retreat of this glacier has been sped up by warmer summers and sea temperatures. Ian Joughin, a glaciologist at the University of Washington believes that the Jakobshavn Isbræ glacier is the one of the fastest moving glaciers in Greenland. This glacier is a key source of Greenland’s melt, drains 6.5% of the Greenland ice sheet and produces around 10% of its icebergs. According to NASA, “This glacier alone could contribute more to sea level rise than any other single feature in the Northern Hemisphere.”

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Jakobshavn glacier since 1851

Alarms have been raised regarding the stability of Greenland’s glaciers. The glaciers, whose role is to hold back ice are getting unstable and are unable to stop ice from reaching the sea. Unfortunately, glaciers in Antarctica are facing the same issues, as well. One of the best solutions would be to stop global warming, mainly by replacing fossil fuels. We have the technology to use alternative sources of energy, already. It would be time to increase investing to them.

 

Written by Kristof Meszaros

 

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