Land Rising Due to Melting Glaciers

The land around Höfn in Hornafjörður is rising rapidly due to the melting of the glaciers in the surrounding area. Normally, the most highlighted issue connected to global warming is the rise of sea levels which threatens communities and land close to sea level. In this case, the exact opposite is true as the land is rising to the tune of one centimetre per year.

“These are profound changes, especially in the area around Vatnajökull glacier,” says Páll Einarsson, professor emeritus in geophysics. The land in the East Iceland area is rising due to the rapid changes taking place for glaciers in the country. “It’s already had considerable effects in Höfn in Hornafjörður. There, the land is rising one centimetre per year,” Páll stated. The municipality of Höfn has invested significantly in construction projects to put a halt to the land-rise, or at the very least lessen its effects. “Hornafjörður is a clear example of the effect of climate change. In Höfn it’s a question of life or death for the town. If land rises significantly, the fjord can start to be impassable for ships.”

Hornafjörður became passable for ships in 1930 when the land had sunk enough for ships to be able to enter the natural lagoon in the area. Before that, a town was situated in nearby Papós í Lóni. That town became deserted as the town of Höfn grew in size. Vatnajökull glacier is the largest glacier in Iceland, covering 8% of the country’s total surface area.

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The area around Höfn í Hornafjörður is rising at a rate of one centimetre per year due to the melting of nearby Vatnajökull glacier.

The Icelandic Geological Survey measures both land rise and the sinking of land each year. “When the glaciers melt and lose weight, the earth’s crust rises. The foundation, the lower part of the crust, as well as the mantle, are soft below Iceland and gives way. It was profound close to the end of the ice age 10 to 18 thousand years ago. Now, the land is answering the glacial changes, which are significant enough for us to be able to measure them.” The land rise is happening at the most rapid rise in the Sprengisandur area. That area has risen about three centimetres per year for the last decades, and the land rise rate is only increasing.

Land sinking in South-West Iceland
The situation is different in South-West Iceland, as the land is sinking there. That part of the country is far from glaciers, but there’s also been a lack of volcanic activity in the area for a long time. “The Reykjanes peninsula sits on the plate boundary where the country is sliding apart. There’s been no volcanic activity there for around 800 years which means that the plate boundary sinks, as there’s a lack of material,” says Páll. This will change in a relatively short time, at least when it comes to geology, as volcanic activity is expected to resume in the next decades or hundreds of years. Areas which are vulnerable to land sinking, such as Seltjarnarnes and Álftanes, have had to react by placing expensive sea walls comprised of large rocks, on the coastline.

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Seltjarnarnes and Álftanes are threatened by rising sea levels. The coastline of both areas has been reinforce with sea walls made of large rocks

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The south-west peninsula of Iceland is sinking due to its placement near the Reykjanes tectonic plate ridge. A lack of volcanic activity in the area has led to a dearth of material.

Greenland glacier affects local conditions
The size of the Greenland glacier affects Iceland in two ways. The glacier has shrunk significantly due to global warming. “The mass of the Greenland glacier draws sea toward itself and forms a sort of sphere. The grand mass of the glacier is disappearing, and the attraction lessens which affects sea levels,” according to Páll. Greenland is rising due to the melting of the glaciers, much like Iceland, and the rise of Greeland also affects Iceland. The material in the mantle streams towards Greenland which leads to the sinking of the land under the South-West part of Iceland. The effect of the glacial changes in Iceland has a more profound effect, though.

Projections indicate that all of the Icelandic glaciers will have disappeared in 200 years due to global warming. “As things stand now, the world temperature appears to be rising. Then, the melting will take place in a shorter time span.”