Cryosphere Lecture 1

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Geochemist and Palaeoclimatologist
Use ultra-rare cosmogenic nuclides to determine dates and rates at the earth surface Work on glacial, periglacial, lacustrine and coastal landforms
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What about anthropogenic drivers?
Not a natural part of the system
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Ice on Earth – interactions
Surface albedo Ice sheet elevation Landscape change CO2 Sea level Ocean circulation Vegetation change
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Ice has the slowest response time ...
10 yr for Franz Josef 10^4 for orbital changes (e.g. Laurentide) 10^6 for tectonic changes (e.g Antarctica)
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The cryosphere includes
mountain /valley glaciers ice caps and ice sheets Icebergs & sea ice also... permafrost snow cover lake ice
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Glacial Distribution controlled by:
Controlled mostly by temperature and precipitation High latitudes High altitudes
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Some glaciers are constrained by topography including:
Icefield (interconnected valley glaciers) Valley glaciers (piedmont, tidewater) Mountain glaciers (>0.01 km2: cirque, niche, glacieret)
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Mountain/Valley Glaciers include
Franz Josef , Khumbu Himal and Grosser Aletshgletscher, Mer de Glace
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Piedmont Glaciers are also
Mountain/Valley Glaciers examples include Axel Heilberg
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Surging glaciers are also
Mountain/valley glaciers (HUbbard Glacier, alaska)
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Tidewater Glaciers
are mountain/valley glaciers (James Ross Island)
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Glaciers unconstrained by topography >50,000 km2 are
Ice sheets
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Glaciers unconstrained by topography
Ice Caps ( these feature ice domes, Ice divides, outlet glaciers etc
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Examples of Ice Caps
Agassiz ice cap, Canada (21,000 km2) Severny Island (20,500 km2) Vatnajökull, Iceland (8,100 km2) Austfonna, Svalbard (8,105 km2)
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Examples of Ice sheets
Only 2 examples at present Antarctica (~14 x 106 km2) Greenland (~ 2 x 106 km2)
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Ice sheets can be
Can be terrestrial (grounded above sea level) or marine based (grounded below sea level)
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Ice sheets Outlet Glaciers
‘Rivers of ice’ Constrained by topography Common in Greenland Often tidewater and example is the permann glacier and the equp sermia glacier
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Ice sheets Ice streams
Constrained by slow flowing ice Common in Antarctica
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Ice shelves
An extension of glacier that floats Grounding line Thickened sea ice Fast ice
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Icebergs
Calve from ice shelves / floating tongues (aka Ross Ice shelf)
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Icebergs
Contains material which melts out where iceberg travels Ice Rafted Debris (IRD) Can be used to date large calving events
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Ice on Earth – the cryosphere
The cryosphere: mountain /valley glaciers ice caps and ice sheets Icebergs & sea ice also... permafrost snow cover lake ice
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Sea ice
Frozen sea water (‘marine’ ice) Seasonal Can be 1 year or multi-year
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Arctic Sea Ice
Max extent in Mar (end northern winter) Min extent in Sept (end northern summer) (inverse in the antartic)
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What about anthropogenic drivers?

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Not a natural part of the system

Card 3

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Ice on Earth – interactions

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Ice has the slowest response time ...

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The cryosphere includes

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