The Iceland Series: Unit 4 – Glaciation

How are glaciers reshaping Iceland?

The Iceland Series: Unit 4 – Glaciation

What is glaciation?

• Glaciation is the process whereby landforms are shaped by the action of glaciers and ice sheets
• Glaciation occurs in regions where temperatures are low enough to form glaciers
• Glaciers are rivers of ice, which move slowly through landscapes: they grow (advance) and shrink (retreat) and as they do this shapes the land
• Glaciers form in areas where snow accumulates over many years and does not fully melt. The weight of snow compresses lower layers to form ice. When this mass of ice becomes large enough it starts to move downhill due to gravity
• Modern glaciers exist only at high-altitude or high-latitude locations
• An area which currently has glaciers is called glaciated, an area which used to have glaciers that have now melted is called deglaciated, and an area which is nearby to glaciers is called periglaciated

The Iceland Series: Unit 4 – Glaciation

The Iceland Series: Unit 4 – Glaciation

• Our planet has experienced multiple ice ages – long periods of time when global temperatures are much lower leading to expansion of ice sheets and glaciers worldwide.
• During an ice age, there are alternating glacial and interglacial periods – times when ice sheets grow, and times when ice retreats due to warming.
• The Last Glacial Maximum was around 21’000 years ago when ice sheets covered 30% of Earth’s land surface and sea levels were 120m lower than today, creating land bridges between continents.
• We are now in a warming interglacial, and by 12’000 years ago most glaciers had melted – making the start of the Holocene epoch we now live in.
• In theory, the next glacial period would start again in 10-50’000 years time, but scientists worry that human-enhanced global warming is altering natural climate cycles making this unpredictable.

A globe that shows the geography, seafloor topography, and extent of ice sheet during the Last Glacial Maximum ~21’000 years ago. Scotese, C.R., 2013

antarcticglaciers.org – Andy Emery

The UK is now a deglaciated area. During the last glacial maximum (LGM) much of the UK was covered in an ice sheet, but it had completely disappeared by 11’300 years ago.

Many of our landforms have been shaped by ice, e.g. Eryri National Park (Snowdonia), Mourne mountains, Scottish Highlands and islands, Lake District, Yorkshire Dales, East Anglia, etc.

The Iceland Series: Unit 4 – Glaciation

The Iceland Series: Unit 4 – Glaciation

• Erosion means the breakdown and removal of material, i.e. rocks, sediment, soil.
• Glaciers erode in a way similar to rivers.
• As glaciers move downhill under gravity the ice erodes the bedrock & valley sides.
• Plucking is when a glacier freezes onto rocks and as it moves then pulls (plucks) rocks away. When meltwater seeps into cracks in rocks it refreezes, expands and this makes it easier for the glacier to pluck the rock out & move it.
• Abrasion is when pieces of rock and debris within the glacier (at the base and edges) are dragged along, acting like sandpaper to scrape away the valley floor and walls and wear them down.
• Freeze-thaw action makes rocks more vulnerable to plucking & abrasion.

Erosion

The Iceland Series: Unit 4 – Glaciation

The Iceland Series: Unit 4 – Glaciation

The Iceland Series: Unit 4 – Glaciation

A glaciated landscape

The Iceland Series: Unit 4 – Glaciation

The Iceland Series: Unit 4 – Glaciation

The Iceland Series: Unit 4 – Glaciation

When glaciers carve through V-shaped river valleys they cut through rock to form steep cliff-like truncated spurs and wide, steep-sided U-shaped valleys with flat floors (glacial troughs).

Arêtes (knife-edge ridges) form when glaciers erode both sides of a mountain, Pyramidal peaks (horn) form when corries erode back towards each other.

Roche moutonnée are asymmetrical rock formations where one side is smoothed by glacial abrasion and the other is steep due to plucking as the ice moves over.

Hanging valleys are smaller valleys left hanging above the main glacial trough (often with waterfalls) formed when the tributary glacier erodes more slowly.

The Iceland Series: Unit 4 – Glaciation

The Iceland Series: Unit 4 – Glaciation

Drumlins beside Hayeswater © Trevor Littlewood cc-by-sa/2.0 :: Geograph Britain and Ireland

Outwash plains (sandur) are flat areas of sorted sediment (larger sediment near the snout, finer sediment further away) deposited by meltwater – often with braided streams

Moraines are deposits of glacial till of different size sediment found as: lateral (along glacier sides), medial (where glaciers merge), terminal (the furthest point ice reaches), or the base

Drumlins are egg-shaped oval mounds of deposited glacial till; they often form in groups in the direction of glacier movement (nicknamed ‘basket of eggs’

Erratics are large boulders transported long distances from their origin and deposited, so they have a different rock type to the local area and show past glacial movement

The Iceland Series: Unit 4 – Glaciation

The Iceland Series: Unit 4 – Glaciation

Types of human activities

• Farming: fertile soils from glacial deposits within flat valleys suitable for agriculture, and meltwater for irrigation
• Hydroelectric power (HEP): glacial meltwater harnessed for renewable energy
• Mining & quarrying: minerals are exposed in deglaciated areas
• e.g. Norway generates over 90% of its electricity from HEP, fed by glacial meltwater

• Winter sports: popular winter tourism in modern glaciated areas includes skiing and snowboarding
• High adventure: activities including glacier hiking & ice climbing, guides tours and scenic helicopter flights
• Cruises & scenic tours: fjords and glacial lakes attract boat tourism
• e.g. Franz Josef and Fox glaciers, New Zealand have around 500’000 tourists a year

• Transport routes: mountain passes for trade and travel connecting people and goods
• Tunnels & roads: engineering projects to allow more direct travel in mountainous areas previously isolated
• Residential: glaciated and deglaciated areas are aesthetically pleasing to attract residents
• e.g. the Karakoram Highway connects Pakistan and China through a glaciated mountain range

• Drinking water: glaciers are natural freshwater reservoirs, providing water to millions (69% of global freshwater in glaciers & ice caps)
• Resource conflict: who owns the ice and water reservoirs, competing demands for water
• Glacial lakes: monitored and dammed to manage outburst floods
• e.g. Andes glaciers provide 50% of Lima’s water

Water supply & water control

Scientific research & conservation

• Glaciology: scientists can learn about climate change and past environments
• Climate monitoring: melting glaciers as indicators of global warming, permafrost used to store global seed banks
• National parks: conservation to protect landscapes and biodiversity
• e.g. Antarctic glaciers and ice-sheets provide a record of climate & volcanic activity

The Iceland Series: Unit 4 – Glaciation

The Iceland Series: Unit 4 – Glaciation

• Today 10% of the world is covered in ice (mostly as ice sheets) with glaciers covering 0.5% of Earth’s land surface
• Since the Last Glacial Maximum global temperatures have risen 4-7°C; this has accelerated with global temperatures rising ~1°C in just the last century
• Glaciers are highly sensitive to climate change; the Alps and Andes have lost 50% of glacial ice
• Increased melting rates due to rising global temperatures (particularly in Arctic and mountainous regions) releases freshwater into the oceans which changes their circulation and threatens to alter monsoons & extreme weather
• Glacier melt threatens water security in many regions (e.g. Himalayan glaciers provide water for over a billion people)
• Loss of ice also affects global albedo, which means less reflection of sunlight and more warming and melting

Current ice cover. [Source: NASA]

Glaciers as carbon stores:

Globally, ice and permafrost acts as stores to lock away atmospheric CO2 and methane from the atmosphere.

As glaciers melt, they release long-term stored carbon which can contribute to further warming (climate feedback loop). This warms permafrost which releases methane – another greenhouse gas.

Melting can also release ancient viruses and bacteria.

The Iceland Series: Unit 4 – Glaciation

• All regions of the world are losing glacial ice, especially in the Arctic, Greenland, Andes and Asian mountains. Glaciers in Antarctica currently contribute less to global sea levels but will be a bigger problem long-term.
• Many mountain glaciers are retreating at double their previous rate
• The loss of glaciers contributes the most to immediate sea-level rise and freshwater resources, whereas ice-sheets are a bigger long-term concern
• Mountain glaciers contribute 25% to current sea level rise, and cause freshwater supply problems, flood risks and ecosystem damage
• If warming continues at the current rate, 75% of glaciers outside of Greenland and Antarctica will vanish
• Scientists wonder whether human activity & increased melting is ‘flipping a switch’ that will change global climate permanently

1986 vs 2019 [Source: NASA]

Funeral for a glacier?!

In 2019, scientists, politicians and activists held a funeral ceremony to mark the disappearance of Okjökull glacier.

This glacier in western Iceland melted away due to climate change. A plaque at the site states:

“A letter to the future. Okjökull is the first Icelandic glacier to lose its status. In the next 200 years, all our glaciers are expected to follow the same path. We know what is happening and what needs to be done. Only you will know if we did it.”

The Iceland Series: Unit 4 – Glaciation

The Iceland Series: Unit 4 – Glaciation

• Sólheimajökull is an outlet glacier flowing out from the larger Mýrdalsjökull ice cap in southern Iceland.
• It is approximately 10km long and 2km wide.
• It is close to Iceland’s Route 1 ring-road and very accessible for researchers and tourists.

The Iceland Series: Unit 4 – Glaciation

Types of human activities

During the LGM, Iceland was mostly covered in ice and at its peak the glacier reached the coast. Since then it has retreated tens of kilometres, but rapid retreat began in the 20th century.

Iceland has warmed 1.4°C since 1900, with reduced snowfall and increased summer melting.

Since 1995 it has retreated over 1km with an average retreat of 50m a year now meaning it may disappear completely within 150 years.

The sign marks where the snout / terminus reached in 2010 – but you can see the glacier has retreated considerably more since.

Sólheimajökull is also influenced by volcanic activity, with Katla volcano below the main glacier and nearby Eyjafjallajökull. Layers of volcanic ash deposited on the glacier enhances its ‘dirty’ appearance and accelerates melting by reducing its albedo – the ability to reflect sunlight – leading to a positive feedback loop.

The volcano also releases geothermal heat which accelerates melting at the base of the glacier, making it weak.

Local school children have been measuring the glacier’s length change annually since 2010, and it has retreated approximately 763m since then.

The Iceland Series: Unit 4 – Glaciation

Like many glaciers, Sólheimajökull experiences conflict involving land use, conservation and tourism. Tourism is important to Iceland, bringing in around $7 billion dollars a year.

High visitor numbers contribute to local economies, particularly for guided tours and glacier hiking, and for accommodation and services. The site is especially popular with school trips as there is a car park on the sandur making it a short walk and an exciting location to explore with ice axes and crampons!

However, tourist numbers increase environmental risks and glacier degradation, so tourism must balance accessibility with sustainability.

The land around the glacier is managed by local authorities, with no single ownership which can make management trickier with more stakeholder views to consider. Local communities rely on glacial rivers for freshwater.

Access roads and parking facilities are regularly relocated as the glacier margins change. Conservation efforts focus on promoting sustainable tourism and minimising environmental damage.

The ice itself is studied for climate research and even extracted to monitor ice composition, movement and retreat patterns. The site is closely monitored using satellite imagery, GPS measurements and climate models to assess ice thinning and retreat.

The Iceland Series: Unit 4 – Glaciation

Bizarrely…

If you visit, you may well see the plane wreck of a U.S. Navy aircraft that crash landed here in 1973!

The plane ran out of fuel and made an emergency landing, and the US military did not recover it.

Now it is partially buried in the black sands but has become a popular spot for tourist photos!

Sólheimajökull glacial deposits have built a vast flat outwash plain (sandur).

Meltwater rivers transport eroded material away from the glacier and sort it, depositing larger materials closer to the snout and finer sand, silt and gravels further away.

Occasionally, a glacial outburst flood (jökulhlaup) following volcanic activity brings a sudden outflow and deposits larger material further away.

The Iceland Series: Unit 4 – Glaciation

Knowledge Summary

Glaciers are large, slow-moving rivers of ice that form when layers of snow compacts in cold climates

Glaciation is the process of glacier formation, movement, and the impact of glaciers on landscapes

Earth has experienced various ice ages and is currently in an interglacial warm period, but climate is changing

Glaciers change landscapes through erosion, transportation and deposition to create new landforms

Glaciers move due to gravity and slide on their base, they can advance downhill but will retreat uphill when melting

Glaciers support life through freshwater supplies, and many alpine settlements rely on glaciers for drinking water, irrigation & agriculture

Glaciers are vulnerable to rising global temperatures, and glacial melt affects ocean currents and local ecosystems

Humans use glaciated and deglaciated areas for water supplies, energy production, settlement, tourism and other economic activities

Sólheimajökull is a glacier in Iceland that is popular with tourists and scientists but is rapidly retreating

Glaciated and deglaciated areas face conflicts for how they should be used & managed

The Iceland Series: Unit 4 – Glaciation