Global glacial mass balance in the last fifty years, reported to the WGMS and NSIDC. The downward trend in the late 1980s is symptomatic of the increased rate and number of retreating glaciers.
 Map of mountain glacier mass balance changes since 1970. Thinning in yellow and red, thickening in blue. The 1970s were a decade of more positive mass balance than the 1980-2004 period as seen above. Crucial to the survival of a glacier is its mass balance, the difference between accumulation and ablation (melting and sublimation). Climate change may cause variations in both temperature and snowfall, causing changes in mass balance. Changes in mass balance control a glacier's long term behavior and is the most sensitive climate indicator on a glacier. Image File history File links Glacier_Mass_Balance. ...
Image File history File links Glacier_Mass_Balance. ...
The World Glacier Monitoring Service (WGMS) was started in 1986, combining the two former services PSFG (Permanent Service on Fluctuations of Glaciers) and TTS/WGI (Temporal Technical Secretary/World Glacier Inventory). ...
The National Snow and Ice Data Center, or NSIDC, is a United States information and referral center in support of polar and cryospheric research. ...
Image File history File links Glacier_Mass_Balance_Map. ...
Image File history File links Glacier_Mass_Balance_Map. ...
A glacier is a large, persistent body of ice, formed largely of compacted layers of snow, that slowly deforms and flows in response to gravity. ...
North-looking oblique aerial photograph showing a small, unnamed hanging glacier located in the Chugach Mountains, near Cordova Peak, Chugach National Forest, Alaska. ...
On a glacier, the zone of ablation or zone of wastage is the area in which annual loss of snow through melting, evaporation, iceberg calving and sublimation exceeds annual gain of snow and ice on the surface. ...
Variations in CO2, temperature and dust from the Vostok ice core over the last 400,000 years For current global climate change, see Global warming. ...
A glacier with a sustained negative balance is out of equilibrium and will retreat, while one with a sustained positive balance is out of equilibrium and will advance. Glacier retreat results in the loss of the low elevation region of the glacier. Since higher elevations are cooler than lower ones, the disappearance of the lowest portion of the glacier reduces overall ablation, thereby increasing mass balance and potentially reestablishing equilibrium. However, if the mass balance of a significant portion of the accumulation zone of the glacier is negative, it is in disequilibrium with the local climate. Such a glacier will melt away with a continuation of this local climate.[1]
The key symptom of a glacier in disequilibrium is thinning along the entire length of the glacier.[2][3] For example, Easton Glacier (pictured below) will likely shrink to half its size, but at a slowing rate of reduction, and stabilize at that size, despite the warmer temperature, over a few decades. However, the Grinnell Glacier (pictured below) will shrink at an increasing rate until it disappears. The difference is that the upper section of Easton Glacier remains healthy and snow-covered, while even the upper section of the Grinnell Glacier is bare, melting and has thinned. Small glaciers with shallow slopes such as Grinnell are most likely to fall into disequilibrium if there is a change in the local climate. Grinnell Glacier with glacier retreat since 1850 of 1. ...
In the case of positive mass balance, the glacier will continue to advance expanding its low elevation area, resulting in more melting. If this still does not create an equilibrium balance the glacier will continue to advance. If a glacier is near a large body of water, especially an ocean, the glacier may advance until iceberg calving losses bring about equilibrium.
Measurement methods
 The Easton Glacier which retreated 255 m from 1990 to 2005 is expected to achieve equilibrium. Image File history File linksMetadata Download high resolution version (2048x1536, 745 KB) Summary M.Pelto, Easton Glacier, North Cascade Glacier climate project www. ...
Image File history File linksMetadata Download high resolution version (2048x1536, 745 KB) Summary M.Pelto, Easton Glacier, North Cascade Glacier climate project www. ...
Image File history File links Grinnell_Glacier2. ...
Image File history File links Grinnell_Glacier2. ...
Grinnell Glacier with glacier retreat since 1850 of 1. ...
There is also a non-adjoining national park by the same name in British Columbia. ...
The United States Geological Survey (USGS) is a scientific agency of the United States government. ...
Mass balance Mass balance is measured by determining the amount of snow accumulated during winter, and later measuring the amount of snow and ice removed by melting in the summer. The difference between these two parameters is the mass balance. If the amount of snow accumulated during the winter is larger than the amount of melted snow and ice during the summer, the mass balance is positive and the glacier has increased in volume. On the other hand, if the melting of snow and ice during the summer is larger than the supply of snow in the winter, the mass balance is negative and the glacier volume decreases. Mass balance is reported in meters of water equivalent. This represents the average thickness gained (positive balance) or lost (negative balance) from the glacier during that particular year.
To determine mass balance in the accumulation zone, snowpack depth is measured using probing, snowpits or crevasse stratigraphy. Crevasse stratigraphy makes use of annual layers revealed on the wall of a crevasse. Akin to tree rings, these layers are due to summer dust deposition and other seasonal effects. The advantage of crevasse stratigraphy is that is provides a two-dimensional measurement of the snowpack layer, not a point measurement. It is also usable in depths where probing or snowpits are not feasible. In temperate glaciers, the insertion resistance of a probe increases abruptly when its tip reaches ice that was formed the previous year. The probe depth is a measure of the net accumulation above that layer. Snowpits dug through the past winters residual snowpack are used to determine the snowpack depth. Snowpack density is another way used to determine mass balance. In either situation the observed depth is multiplied by the snowpack density to determine the accumulation in water equivalent. It is necessary to measure the density in the spring as snowpack density varies. Measurement of snowpack density completed at the end of the ablation season yield consistent values for a particular area and need not be measured every year. In the ablation zone, ablation measurements are made using stakes inserted vertically into the glacier either at the end of the previous melt season or the beginning of the current one. The length of stake exposed by melting ice is measured at the end of the melt (ablation) season. Most stakes must be replaced each year or even mid-way through the summer. Measuring snowpack in a crevasse on the Easton Glacier, North Cascades, USA A crevasse is a crack or fissure in a glacier or snow field. ...
Stratigraphy, a branch of geology, studies rock layers and layering (stratification). ...
 Measuring snowpack in a crevasse on the Easton Glacier, North Cascades, USA, the two dimensional nature of the annual layers is apparent
 Measuring snowpack on the Taku Glacier in Alaska, this is a slow inefficient but accurate process Image File history File linksMetadata Glaciercrevasse. ...
Image File history File linksMetadata Glaciercrevasse. ...
Image File history File links Download high-resolution version (865x576, 46 KB) Digging a snowpit on Taku Glacier, in Alaska to measure snowpack depth and density (Pelto, www. ...
Image File history File links Download high-resolution version (865x576, 46 KB) Digging a snowpit on Taku Glacier, in Alaska to measure snowpack depth and density (Pelto, www. ...
Net balance Net balance is the mass balance determined between successive mass balance minimums. This is the stratigraphic method focusing on the minima representing a stratigraphic horizon. In the northern mid-latitudes, a glacier's year follows the hydrologic year, starting and ending near the beginning of October. The mass balance minimum is the end of the melt season. The net balance is then the sum of the observed winter balance (bw) normally measured in April or May and summer balance (bs) measured in September or early October.
 Measuring snowpack on the Easton Glacier by probing to the previous impenetrable surface, this provides a quick accurate point measurement of snowpack Image File history File links Probingglacier. ...
Image File history File links Probingglacier. ...
Annual balance Annual balance is the mass balance measured between specific dates. The mass balance is measured on the fixed date each year, again sometime near the start of October in the mid northern latitudes.[4]
Geodetic methods Geodetic methods are an indirect method for the determination of mass balance of glacier. Maps of a glacier made at two different points in time can be compared and the difference in glacier thickness observed used to determine the mass balance over a span of years. This is best accomplished today using Differential Global Positioning System. Sometimes the earliest data for the glacier surface profiles is from images that are used to make topographical maps and digital elevation models. Aerial mapping or photogrammetry is now used to cover larger glaciers and icecaps such found in Antarctica and Greenland, however, because of the problems of establishing accurate ground control points in mountainous terrain, and correlating features in snow and where shading is common, elevation errors are typically not less than 10 m (32 ft).[5] Laser altimetry provides a measurement of the elevation of a glacier along a specific path, e.g., the glacier centerline. The difference of two such measurements is the change in thickness, which provides mass balance over the time interval between the measurements. Again a good method over a span of time but not for annual change detection. The value of geodetic programs is providing an independent check of traditional mass balance work, by comparing the cumulative changes over ten or more years.[6] The Global Positioning System (GPS) is currently the only fully functional Global Navigation Satellite System (GNSS). ...
Cartography or mapmaking (in Greek chartis = map and graphein = write) is the study and practice of making maps or globes. ...
3D rendering of a DEM of Tithonium Chasma on Mars A digital elevation model (DEM) is a digital representation of ground surface topography or terrain. ...
Photogrammetry is a measurement technology in which the three-dimensional coordinates of points on an object are determined by measurements made in two or more photographic images taken from different positions (see stereoscopy). ...
Mass balance research worldwide Mass balance studies have been carried out in various countries worldwide, but have mostly conducted in the Northern Hemisphere due to there being more mid-latitude glaciers in that hemisphere. The Northern Hemisphere is the half of a planets surface (or celestial sphere) that is north of the equator (the word hemisphere literally means half ball). On the Earth, the Northern Hemisphere contains most of the land and about 88-90% of the human population. ...
Alaska The Taku Glacier near Juneau, Alaska has been studied by the Juneau Icefield Research Program since 1946, and is the longest continuous mass balance study of any glacier in North America. Taku is the world's thickest known temperate alpine glacier, and experienced positive mass balance between the years 1946 and 1988, resulting in a huge advance. The glacier has since been in a negative mass balance state, which will may result in a retreat if the current trends continue.[7] Taku Glacier is a tidewater glacier located in Taku Inlet in the U.S. state of Alaska, just southeast of the city of Juneau. ...
Location in Juneau City and Borough, Alaska Coordinates: Country United States State Alaska Borough Juneau City and Borough Founded 1881 Incorporated 1890 - Mayor Bruce Botelho Area - City 3,255. ...
World map showing North America A satellite composite image of North America. ...
Austrian Glacier Mass Balance The mass balance of Hintereisferner and Kesselwandferner glaciers in Austria have been continuously monitored since 1952 and 1965 respectively. Having been continuously measured for 55 years, Hintereisferner has one of the longest periods of continuous study of any glacier in the world, based on measured data and a consistent method of evaluation. Currently this measurement network comprises about 10 snow pits and about 50 ablation stakes distributed across the glacier. In terms of the cumulative specific balances, Hintereisferner experienced a net loss of mass between 1952 and 1964, followed by a period of recovery till 1968. Hintereisferner reached an intermittent minimum in 1976, briefly recovered in 1977 and 1978 and has continuously lost mass in the 30 years since then.[8]
New Zealand Glacier mass balance studies have been ongoing in New Zealand glaciers since 1957. Tasman Glacier has been studied since then by the New Zealand Geological Survey and later by the Ministry of Works, measuring the ice stratigraphy and overall movement. However, even earlier fluctuation patterns were documented on Franz Josef and Fox Glaciers in 1950. Other glaciers on the South Island studied include Ivory Glacier since 1968, while on the North Island, glacier retreat and mass balance research has been conducted on the glaciers on Mount Ruapehu since 1955. On Mount Ruapehu, permanent photographic stations allow repeat photography to be used to provide photographic evidence of changes to the glaciers on the mountain over time.[9] Mount Cook area from LandSat. ...
Categories: New Zealand geography stubs | Glaciers of New Zealand | West Coast, New Zealand ...
== == == == Ice cave in the terminal face of Fox glacier. ...
The South Island The South Island is one of the two major islands of New Zealand, the other being the North Island. ...
North Island The North Island is one of the two main islands of New Zealand, the other being the South Island. ...
Composite satellite image of Ruapehu Mount Ruapehu, or just Ruapehu, is an active stratovolcano, situated at the southern end of the Taupo Volcanic Zone in New Zealand. ...
North Cascade glacier mass balance program The North Cascade Glacier Climate Project measures the annual balance of 9 glaciers, more than any other program in North America. These records extend from 1984–2005 and represent the only set of records documenting the mass balance changes of an entire glacier clad range. To monitor an entire glaciated mountain range in North America, which was listed as a high priority of the National Academy of Sciences in 1983. North Cascade glaciers annual balance has averaged −0.52 m/a from 1984–2005, a cumulative loss of over 12.5 m or 20–40% of their total volume since 1984 due to negative mass balances. The trend in mass balance is becoming more negative which is fueling more glacier retreat and thinning.[10]
Norway mass balance program Norway maintains the most extensive mass balance program in the world and is largely funded by the hydropower industry. Mass balance measurements are currently performed on twelve glaciers in Norway. In southern Norway six of the glaciers have been measured for 42 consecutive years or more, and they constitute a west-east profile reaching from the very maritime Ålfotbreen Glacier, close to the western coast, to the very continental Gråsubreen Glacier, in the eastern part of Jotunheimen. Storbreen Glacier in Jotunheimen has been measured for a longer period of time than any other glacier in Norway, a total of over 55 years, while Engabreen Glacier has the longest series (35 years) in northern Norway. The Norwegian program is where the traditional methods of mass balance measurement were largely derived.[11] View from Knutshøi towards central Jotunheimen Jotunheimen is a mountain range in southern Norway covering an area of roughly 3,500 km². It is part of the long Scandinavian Mountains range. ...
Sweden Storglaciären The Tarfala Research Station in the Kebnekaise region of northern Sweden is operated by Stockholm University. It was here that the first mass balance program was initiated immediately after World War Two, and continues to the present day. This survey was the initiation of the mass balance record of Storglaciären Glacier, and constitutes the longest continuous study of this type in the world.[12] Kebnekaise (from Sami Giebmegáisi or Giebnegáisi), Cauldron Crest) is the highest mountain in Sweden. ...
Stockholm University (Stockholms universitet) is a state university in Stockholm, Sweden. ...
This article is becoming very long. ...
Swiss mass balance program Temporal changes in the spatial distribution of the mass balance result primarily from changes in accumulation and melt along the surface. As a consequence, variations in the mass of glaciers reflect changes in climate and the energy fluxes at the earth's surface. The Swiss glaciers Gries in the central Alps and Silvretta in the eastern Alps, have been measured for many years. The distribution of seasonal accumulation and ablation rates are measured in-situ. Traditional field methods are combined with remote sensing techniques to track changes in mass, geometry and the flow behaviour of the two glaciers. These investigations contribute to the Swiss Glacier Monitoring Network and the International network of the World Glacier Monitoring Service (WGMS).[13] The west face of the Petit Dru above the Chamonix valley near the Mer de Glace. ...
The World Glacier Monitoring Service (WGMS) was started in 1986, combining the two former services PSFG (Permanent Service on Fluctuations of Glaciers) and TTS/WGI (Temporal Technical Secretary/World Glacier Inventory). ...
United States Geological Survey (USGS) The USGS operates a long-term "benchmark" glacier monitoring program which is used to examine climate change, glacier mass balance, glacier motion, and stream runoff. This program has been ongoing since 1965 and has been examining three glaciers in particular. Gulkana Glacier in the Alaska Range and Wolverine Glacier in the Coast Ranges of Alaska have both been monitored since 1965, while the South Cascade Glacier in Washington State has been continuously monitored since the International Geophysical Year of 1957. This program monitors one glacier in each of these mountain ranges, collecting detailed data to understand glacier hydrology and glacier climate interactions.[14] This image shows the termini of the glaciers in the Bhutan-Himalaya. ...
View of Denali, the centre piece of the Alaska range, on a rare clear day . The Alaska Range is a mountain range that extends for about 650 km (400 mi) across south-central Alaska, from Iliamna Lake at the SW end to White River in Canada at the SE end. ...
The Pacific Coast Ranges are the series of mountain ranges that stretch along west coast of North America from Alaska to Mexico. ...
Official language(s) English Capital Juneau Largest city Anchorage Area Ranked 1st - Total 663,267 sq mi (1,717,855 km²) - Width 808 miles (1,300 km) - Length 1,479 miles (2,380 km) - % water 13. ...
Official language(s) English Capital Olympia Largest city Seattle Area Ranked 18th - Total 71,342 sq mi (184,827 km²) - Width 240 miles (385 km) - Length 360 miles (580 km) - % water 6. ...
The International Geophysical Year or IGY was an international scientific effort that lasted from July 1, 1957, to December 31, 1958. ...
Cited references Image File history File links Commons-logo. ...
The Wikimedia Commons (also called Wikicommons) is a repository of free content images, sound and other multimedia files. ...
References - ^ Dyurgerov, M. (M. Meier and R. Armstrong, eds.). Glacier mass balance and regime measurements and analysis, 1945–2003. Institute of Arctic and Alpine Research, University of Colorado. Distributed by National Snow and Ice Data Center, Boulder, CO..
- ^ Mauri S. Pelto (Nichols College). The Disequilibrium of North Cascade, Washington Glaciers 1984–2004. In "Hydrologic Processes". Retrieved on February 14, 2006.
- ^ Pelto, M.S. and Hartzell, P.L. (2004). "Change in longitudinal profile on three North Cascades glaciers during the last 100 years". Hydrologic Processes 18: 1139–1146.
- ^ Mauri S. Pelto, Director NCGCP (March 28). Glacier Mass Balance. North Cascade Glacier Climate Project.
- ^ David Rippin, Ian Willis, Neil Arnold, Andrew Hodson, John Moore, Jack Kohler and Helgi Bjornsson (2003). "Changes in Geometry and Subglacial Drainage of Midre Lovénbreen, Svalbard, Determined from Digital Elevation Models". Earth Surface Processes and Landforms 28: 273–298.
- ^ Andreas Bauder, G. Hilmar Gudmundsson (March 28). Mass Balance Determination using Photogrammetric Methods and Numerical Flow Modeling. Laboratory of Hydrolic, Hydrology and Glaciology.
- ^ Pelto, Mauri; Matt Beedle, Maynard M. Miller. Mass Balance Measurements of the Taku Glacier, Juneau Icefield, Alaska 1946-2005. Juneau Icefield Research Program. Retrieved on 2007-01-09.
- ^ Mass balance of Hintereisferner. Institute for Meteorology and Geophysics, University of Innsbruck, Austria (January 20, 2004). Retrieved on 2007-01-09.
- ^ Glaciers of New Zealand. Satellite Image Atlas of Glaciers of the World. U.S. Geological Survey. Retrieved on 2007-01-16.
- ^ Pelto, Mauri (November 9, 2006). Glacier Mass Balance. United States Mass Balance Surveys. Retrieved on 2007-01-09.
- ^ Norwegian Water Resources and Energy Directorate (March 28). Mass balance measurements. Glaciological investigations in Norway.
- ^ Storglaciären. Stockholm University (February 9, 2003). Retrieved on 2007-01-09.
- ^ Bauder, Andreas; Martin Funk (March 20, 2006). Mass Balance Studies on Griesgletscher and Silvrettagletscher. The Swiss Glaciers. Laboratory of Hydraulics, Hydrology and Glaciology, Swiss Federal Institute of Technology. Retrieved on 2007-01-09.
- ^ Benchmark Glaciers. Water Resources of Alaska-Glacier and Snow Program. United States Geological Survey (July 9, 2004). Retrieved on 2007-01-09.
|
Feeds |
Contact