Global Distribution of Glaciers
- Present day distribution of cold environments can be divided into polar, glacial, alpine and periglacial areas
- Polar - considered areas of permanent ice within the northern and southern extremes of the Antarctic and Arctic regions
- Therefore, found in areas of high latitude, with long winters and short summers, with high levels of storms and cold winds
- Arctic polar environment can be defined either by the Arctic circle at 66° N or by the July isotherm of 10° C
- Isotherms are areas of the same temperature
- July is the hottest month and areas north of this line have an average of 10°C or below
- Winter sea ice is shrinking
- The Antarctic is much colder than the Arctic, with strong westerly winds, cold oceans and a large landmass
- Winter sea ice is increasing
- Defined by the 10°C January isotherm (January is the hottest month in the southern hemisphere)
- Arctic polar environment can be defined either by the Arctic circle at 66° N or by the July isotherm of 10° C
- Other examples include Greenland and northern Canada
Distribution of present day cold environments
- Alpine
- Found at any latitude but at high altitudes of over 3000m, where snow and ice remain throughout the year at higher altitudes, and has a cooler climate and seasonal coverage of snow at lower altitudes
- Landscape includes ice caps, mountain glaciers and tundra, developed over glacial and interglacial periods
- Tectonic uplift and rapid erosion by water and ice have created well-developed glacial landforms
- Examples include the Himalayan and Tibetan mountain ranges in Asia, the Rockies and the Andes in the Americas, and the New Zealand Alps
- Glacial
- Found at higher latitudes and altitudes, with high levels of precipitation, at the edges of polar ice sheets and alpine glaciers
- Ice remains throughout the year
- Examples include the Andes, Himalayas and Franz Josef Glacier, NZ
- Periglacial (tundra)
- Located at the fringes of permanent glaciated areas, either at high altitude alpine regions or high latitude polar regions and accounts for a third of the Earth's surface
- Characterised by permafrost (large sections of permanently frozen ground) and an ‘active layer’ of seasonal thawing and re-freezing surface; up to 5 meters in depth
Exam Tip
Remember that permafrost is not needed in the development of all periglacial landforms, however, most periglacial environments have permafrost and this influences the processes that form the periglacial landscape.
