The Complete Guide to Glaciers in Iceland
Everything you have ever wanted to know about glaciers in Iceland
Glaciers are one of the world’s most fascinating natural environments due to their dynamic and fluid nature. Currently they cover about 10% of the world’s total land area in ice and can be found in every continent. Here in Iceland approximately 14% of the country is covered by glaciers, with one single glacier, Vatnajökull, taking up 8% of the landmass.
In order for a glacier to form it requires certain climatic conditions, such as high levels of precipitation in the form of snow or freezing rain during the winter, and cool temperatures in the summer. This is to ensure the snowfall accumulation gained in the winter is higher than the snow lost during the summers by calving, melting and evaporation.
Glaciers can range in size from the smallest being the size of a football pitch, to glaciers stretching over 100km long. They are formed by snow that consistently accumulates over an area and compresses older snow that lies underneath it. Eventually the increasing pressure on the snow turns it into firn, which is a highly compact form of snow and thus leads to the formation of ice. As the weight increases, newly formed ice crystals become larger as air is squeezed out of the ice, this causes the blue colour of glacial ice.
Another key feature of a glacier is the way they flow like extremely slow rivers. Glaciers can be generalised into two types: continental, which flow outwards, and alpine, which flow downwards.
Alpine glaciers are pulled down the valleys due to gravity and their tremendous weight, and movement is caused by internal deformation which causes sliding at the base of the ice. This sliding occurs due to melt water seeping through cracks in the glacier, however the high pressures experienced under the ice can cause it to melt. Movement can also occur by ‘basal slip’, which is where soft sediment (containing water) slips causing the glacier to slide. In general, movement in glaciers is quite slow, with faster movement occurring at the top as opposed to the bottom, however glaciers can experience rapid movements. These rapid movements are called surges and glaciers may surge forwards moving several times faster than its usual speed, with glaciers in Alaska observed to surge tens of metres a day.
Glaciers have a massive impact on their surrounding environment and are responsible for sculpting various mountains, carving out valleys and creating fjords. The glaciers achieve this erosion, via two methods, abrasion and plucking. The abrasion is caused by ice picking up small rock debris smaller than 0.002mm and using this like sand paper; the end result of this is steeper mountains and valley walls. Abrasion can also cause large glacier striations if the glacier picks up large boulders (larger than 300mm) and carves them along the rock bed. The other process of erosion is plucking, this is caused by glacial water penetrating cracks in the rock bed, freezing, and then expanding causing rocks to be plucked by a lever mechanism. This causes the glacier to pick up debris of all sizes. The end result of the debris being carried by a glacier creates lines of glacial till called Moraines, furthermore this can show the previous glacial maximum.
Moulin & Crevasses
Some features of glaciers such as moulins and crevasses, are very dynamic and may spontaneously appear and shape the glacial over a short space of time.
Along the surface of a glacier stream, melt water can be seen disappearing into holes, these holes are called moulins. They come in a range of sizes and can reach to the bottom of the glacier and flow all the way to the terminus, the end point of a glacier. These holes are believed be formed by small debris heating up the surface of a glacier causing small ponds to appear, as they become deeper the debris starts to mill tunnels into the ice.
Crevasses are giant cracks which can appear with a glacial sporadically. This is due to the movement of the glacier, where the centre and upper layers move quicker than the sides and base layer of ice due to the friction generated by the rocks. These crevasses are typically wedge shaped and can run along the entire length of a glacier, reaching to depths of around 45 metres and 20 metres wide. Snow bridges can form over these crevasses covering them up, however they can be very unstable, thus making travel across a glacier tough and perilous.
Over the past 750,000 years there has been eight ice age cycles, these ice ages meant that the glacial extent was at a maximum, this meant that 32% of the world’s land and 30% of the oceans were covered by ice, as opposed to 10% of today’s lands being covered in ice. During the last ice age, Scandinavia, Iceland, Arctic islands, most of Canada and the upper Midwest were covered in ice. The earth experienced a “little ice age’’ between the 17th to late 19th century, where glaciers were able to advance due to consistently cool temperatures. The earth is now believed to be approaching its next ice age cycle in next few 1000 years, however it remains unclear whether global warming will delay the onset of this cycle.
There is no doubt within the scientific community that since 1970s the earth has been warming at a greater rate than in the last one thousand years. Greenhouse gases are believed to be the cause of climate change, with carbon dioxide levels increasing since the mid-19th century and even more noticeably during the last five decades. Glaciers all over the world have tended to retreat over the past 60 to 100 years with alpine glaciers being the most susceptible and unstable, although it is unclear whether this is due to climate trends or human induced climate change. Furthermore scientists are able to take a glimpse at the earth’s previous atmosphere since it is locked within the ice, thus provide clues to previous climates.
Glaciers and ice sheets are extremely important on a global scale since they affect sea levels, weather and provide fresh water to their surroundings. The effects of warming air temperatures in the Polar Regions have caused various negative effects such as sea level rise. This is a major problem since glaciers store about 75% of the world’s freshwater supply, melting of all the ice could cause sea levels to raise by roughly 70 metres globally. Even a sea level rise of just two metres could cause devastation to many costal environments. Glaciers can also affect the weather due to the cold air around the poles and warm air at the equator creating a temperature differential, resulting in complex jet streams of wind and storm formations across the globe.
Glaciers also have a big impact of people living nearby providing freshwater to irrigate crops, sources of renewable energy by hydroelectric power plants damming glacial melt water. Glaciers also provide important drinking water to many people in places such as Nepal and India, declines in this supply would cause local populations to become more dependent on unreliable monsoons.