Glaciers and Climate Change Flashcards
At the largest spatial and temporal scales, an increase in temperature leads to…
At smaller scales…
Sea level rise
Its not that simple
What’s the link between glaciers and climate?
Glacier mass balance
What are the factors driving glacier responses to climate change?
Glacier temperature Subglacial hydrology Nature of the bed Surges Aquatic margin Size, shape, aspect
What is glacier temperature dependent on?
Metamorphism- how easily it turns from snow to ice
Response to mass balance changes
- longest for long or slowly flowing glaciers
What is hypsometry?
Distribution of glacier area over its altitudinal range
What is AAR?
Accumulation area ratio- ratio between accumulation area and area of entire glacier.
What does Hughes (1986) suggest happens when ice streams enter the water at the aquatic margin?
There is enhanced fast flow.
Fast flow leads to increased crevassing.
Enhanced calving and allow penetration of meltwater into bed.
Increased flow.
Reasons for dramatic melting
It has been argued that enhanced basal lubrication.
- Increased melting = more water down to the bed = increased lubricated = glacier shoot forward = lower altitudes = more melting
Hydro-fracturing of water filled crevasses- accompanied by a release of back stresses
- Water can come from the bottom up where the glacier is floating cracking them open wider, flowing faster
Early development of the summer channelised system (bed already lubricated)
- the hydrological system adapts to extra water so it can’t go any faster remaining stable
Calving
- Once the glacier meets a water body, the heat from the water will cause calving
Internal effects/ surges are…
Irrespective of global warming
Rigid bed model (Kamb et al., 1985)
High water pressure ->
Increased sliding
Increased cavitation
Changes system from a tunnel to linked cavity system
Deforming bed model (Clark et al., 1984)
High water pressure ->
Surge triggered by destruction of the drainage system due to deformation of the till
Thermal/ deformation (Murray et al., 2003)
Cold toe - ice builds up until pmp reached
Increased meltwater Basal sliding More heat More melting Until ice thins and refreezing
Storage (Lingle and Fatland, 2003)
Water added to englacial storage
In winter this drains- too much for the constricted winter system, and basal sliding or till failure
Mass and energy flux (Sevestre and Benn, 2015)
Glacier must be in balance (heat convection or drainage system)
Typical ‘in balance’ glaciers
- temperate wet
- small cold dry
Typical ‘out of balance’
- large cold dry
- polythermal
- temperature dry
From here just read off slides- Non climatic? What has recent warming meant?
Glaciers can’t surge
