Threats Facing Glaciated Landscapes (Edexcel A Level Geography)

• Active and relict glacial landscapes are inherently dangerous: 
  • Avalanches
  • Rock falls
  • Debris slides
  • Flooding
• Increased populations, developments, and tourism put people at risk within these areas

Avalanches

• Avalanches are rapid movements of snow down a slope, and are common in mountainous areas
• Avalanches occur when shear stress exceeds the shear strength of a mass of snow on a slope, which is linked to the snow's density and temperature
• Two types of pack snow failure:
  • Loose snow - small amounts of snow move and roll down the slope
  • Slab avalanches - large 'slabs' of snow break away from underlying snow
    • This type of avalanche is the most dangerous 
    • A large, fully-developed avalanche can weigh up to a million tonnes
    • Created when higher temperatures are followed by a freeze, creating an 'ice crust' on the surface, which is unstable
• Avalanches start with a glide and then accelerate to speeds of 320km per hour (200m per hour), picking up even more snow as it rushes downhill
• Occur most frequently on slopes over 22°
• Also, occur on north-facing slopes where the lack of snow limits snow stability (doesn’t have time to bind with partial melting)
• Three types of avalanches are: 
  
  • New snow can fall off older snow (dry avalanche)
  • Or partially melted snow moves (wet avalanche)
  • Mostly from slab avalanches (powder avalanches)
    • A powder cloud forms with a large quantity of snow being suspended in the air
    • These are the most dangerous of avalanches 
• All avalanches are a significant hazard and kill approximately 200 people a year

Lahars

• A lahar is a large mud and debris flow as a result of volcanic activity
  • Nevado del Ruiz, Colombia is known locally as the ‘sleeping lion’ and has not erupted for nearly 150 years
  • In the early hours of November 13th, 1985 it erupted
  • A combination of seismic activity, glacial instability, and extreme temperatures all combined to form one of the deadliest mudflows in history
  • Occurred during the night when most of the 27000 residents of Armero in Tolima were asleep
  • Armero was virtually destroyed by the 3-8m of mud and rubble that swept onto it and killed an estimated 23,000 people

Glacial outburst floods (GOFs)

• Powerful floods caused by the sudden release of meltwater from a subglacial or ice moraine-dammed lake
• Can be trigged in six ways:
  • Overflow and melting of the ice dam
  • Breakdown of ice dam due to tectonic activity
  • Increased rise in water levels
  • Mass movement creating an overtopping of the moraine dam through displacement
  • Catastrophic failure of moraine dam by slow ice melt within the moraine
  • Increased water pressure enlarging pre-existing tunnels beneath the ice dam
• GOFs can be seasonal and dams can reform each year
• These outbursts are sudden and pose a threat to property and people around the world
• Meltwater can travel hundreds of kilometres from its sources and areas such as the Alps, Iceland, the Andes, and the Himalayas have a long history of GOFs
• Periglacial areas are also seeing increased ground subsidence due to ice melt and flooding, risking new areas to sudden flooding

• Glaciated landscapes face varying degrees of threat from human activities:
  • Urbanisation
  • Reservoir construction
  • Leisure and tourism

Urbanisation

• Vary from isolated farms to nucleated towns depending on the location
• Relict glaciated areas are traditionally agricultural with intermittent market towns
• The impact varies on accessibility, but with the growth of tourism and the general population, many of these areas have seen a rise in development, pollution, and damage/loss of flora and fauna habitats
• Infrastructure developments can damage permafrost and increase rates of melting through the release of greenhouse gases into the atmosphere
• The exploitation of resources and discovery of new areas have increased risks of pollution by toxic waste from the mining of gold, copper, or uranium 
• Oil and gas spills into the polar waters have damaged the fragile balance of oceanic ecosystems which cascades onto land-based ecosystems

Reservoir construction

• The construction of reservoirs in valleys is leading to landscape and hydrological changes
• Upland glacial landscapes provide natural features for HEP and reservoir building 
• Power from HEPs provides power to urban areas
• Reservoirs regulate water supplies
• However, they also dramatically alter the landscape and impact a river's regime
  • The River Ganges rises in the Himalayas and discharges in Bangladesh
  • The glacial waters provide for many people, animals, and plants along its course
  • With the increased planned and constructed HEPs along its course, the impact is far-reaching with decreased water supplies and sediment supplies to areas downstream that rely on the river for their existence

Tourism

• Places such as Antarctica have seen an increase in the number of tourists
• Approximately 100,000 tourists visit Antarctica each year, and large cruise ships increase pollution in the area - both from the ship and the tourists themselves 
• Seeds from non-native species, caught on tourist clothing, are being seen growing in the ice-free coastal areas, threatening the continent's biodiversity
• Adventure tourism to extreme cold environments is a growth industry for countries and local communities
• Developments such as roads and hotels, disrupt wildlife and damage habitats and migratory patterns, leading to reduced biodiversity
• In the European Alps, social mobility and wealth have increased the rate of deforestation for ski resorts and supporting infrastructure, leading to habitat loss and fragmentation
• Tourism increases demand for energy and water resources
• In Zemett, Switzerland, snow cannons add artificial snow to the slopes, but they are energy-intensive and add chemical and biological additives to the soil in the process
• Relict glaciated landscapes are also under threat from tourism
  • Trekking causes damage to fragile mountain ecosystems
  • Plant communities, such as tundra flower meadows, need just 25 people a week and damage begins

• Human activity can degrade the landscape and fragile ecology of glaciated landscapes through:
  • Soil erosion
  • Trampling
  • Landslides
  • Deforestation

Cold environments are fragile

• Natural development and processes within cold environments occur slowly 
• They are long-term carbon and methane stores with a high albedo of up to 90% reflection of insolation
• Any changes quickly cascade, and once damaged, it takes a long time for the ecosystem to recover, if at all
• Adaptations of flora and fauna occurred over a long period of time, in order to survive their harsh surroundings 
• Plants and animals have to cope with a lack of daylight, climatic variations, and a very short growing season
• Specialism, limited species numbers, sensitivity to changes, and slow development make this environment very fragile

Impacts

• Ecosystems are resilient, however, they all have a threshold of tolerance and once crossed, can tip the ecosystem into a spiral of decline
• Certain human activities have a bigger impact than others
• Mountain biking or horse trekking are more damaging than walking
• Deforestation and poor upland farming lead to soil erosion and landslides 
  • Soil erosion is a major issue in the Andes, through over-cultivation and overgrazing on the slopes, in the need to provide subsistence for its growing populations
• Exposed soils allow for weeds, resistant to erosion, to take over
• Leisure activities damage ecosystems through trampling and compaction
  • Small leaves and delicate stems are damaged
  • This reduces photosynthesis, growth, and biomass
  • This provides less water and nutrients to the ecosystem
  • Continued trampling compacts the soil leading to poor soil condition, bare soil, and greater erosion
  • People will avoid rutted and exposed soil but fail to realise that walking on other areas leads to further damage