Glacial systems

• glacier inputs

  snow

  condensation

  freezing of water vapor to ice

  rock debris
• outputs of a glacier

  ablation of meltwater

  evaporation

  calving

  sublimation of ice to water vapor
• stores in a glacier

  ice

  meltwater contained in supraglacial lakes

  snow
• glacial flows

  channel flow of meltwater

  debris and rock fragments transported via subglacial, englacial, and supraglacial channels of meltwater
• positive feedback example

  ice has a high albedo meaning it reflects radiation back to space more than it absorbs it

  as a glacier retreats, there is less ice covering the ocean

  the ocean has a low albedo as it has a dark surface meaning that it absorbs radiation more than it reflects it

  this causes ocean temperatures to rise which increases the melting of ice
• negative feedback example

  increased accumulation of snow and ice increases the overall mass of the glacier

  this increases the amount of solar radiation reflected back out to space as there is a higher surface area of ice that has a high albedo

  this overall leads to more accumulation of ice as the glacier advances
• zone of accumulation

  point at which on a glacier accumulation > ablation

  there is a positive regime
• dynamic equilibrium

  accumulation and ablation are in balance throughout the year

  however they can be subject to short term variations

  the glacial budget shows the overall mass balance of a glacier
• what can change the glacial budget

  seasons

  Milankovitch orbital cycles

  climate change

  volcanic eruptions
• example of a glacier showing mass balance change

  kleinelend glacier in the austrian alps

  in 2000 to 2011 the glacier retreated

  however there were multiple years within that period where the glacier advanced including 2001 and 2008
• last glacial period ended

  11000 years ago
• three main epoch

  Pleistocene

  Holocene

  Anthropocene
• how much has the mer de glace glacier retreated

  2.4 km since 1850