Cryosphere Lecture 1 0.0 / 5 ? GeographyCryosphereUniversityNone Created by: P GREENWOODCreated on: 02-01-17 21:21 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 1 of 24 What about anthropogenic drivers? Not a natural part of the system 2 of 24 Ice on Earth – interactions Surface albedo Ice sheet elevation Landscape change CO2 Sea level Ocean circulation Vegetation change 3 of 24 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) 4 of 24 The cryosphere includes mountain /valley glaciers ice caps and ice sheets Icebergs & sea ice also... permafrost snow cover lake ice 5 of 24 Glacial Distribution controlled by: Controlled mostly by temperature and precipitation High latitudes High altitudes 6 of 24 Some glaciers are constrained by topography including: Icefield (interconnected valley glaciers) Valley glaciers (piedmont, tidewater) Mountain glaciers (>0.01 km2: cirque, niche, glacieret) 7 of 24 Mountain/Valley Glaciers include Franz Josef , Khumbu Himal and Grosser Aletshgletscher, Mer de Glace 8 of 24 Piedmont Glaciers are also Mountain/Valley Glaciers examples include Axel Heilberg 9 of 24 Surging glaciers are also Mountain/valley glaciers (HUbbard Glacier, alaska) 10 of 24 Tidewater Glaciers are mountain/valley glaciers (James Ross Island) 11 of 24 Glaciers unconstrained by topography >50,000 km2 are Ice sheets 12 of 24 Glaciers unconstrained by topography Ice Caps ( these feature ice domes, Ice divides, outlet glaciers etc 13 of 24 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) 14 of 24 Examples of Ice sheets Only 2 examples at present Antarctica (~14 x 106 km2) Greenland (~ 2 x 106 km2) 15 of 24 Ice sheets can be Can be terrestrial (grounded above sea level) or marine based (grounded below sea level) 16 of 24 Ice sheetsOutlet Glaciers ‘Rivers of ice’ Constrained by topography Common in Greenland Often tidewater and example is the permann glacier and the equp sermia glacier 17 of 24 Ice sheetsIce streams Constrained by slow flowing ice Common in Antarctica 18 of 24 Ice shelves An extension of glacier that floats Grounding line Thickened sea ice Fast ice 19 of 24 Icebergs Calve from ice shelves / floating tongues (aka Ross Ice shelf) 20 of 24 Icebergs Contains material which melts out where iceberg travels Ice Rafted Debris (IRD) Can be used to date large calving events 21 of 24 Ice on Earth – the cryosphere The cryosphere: mountain /valley glaciers ice caps and ice sheets Icebergs & sea ice also... permafrost snow cover lake ice 22 of 24 Sea ice Frozen sea water (‘marine’ ice) Seasonal Can be 1 year or multi-year 23 of 24 Arctic Sea Ice Max extent in Mar (end northern winter) Min extent in Sept (end northern summer) (inverse in the antartic) 24 of 24
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