The retreat of glaciers since 1850 affects the availability of fresh water for irrigation and domestic use, recreation of mountains, animals and plants that depend on glacier melting, and, in the long term, ocean levels. Studied by glaciologists, the temporal coincidence of glacier retreats with an increase in greenhouse gases in the atmosphere is often referred to as concrete evidence of global warming. Mid-latitude mountain ranges such as the Himalayas, the Alps, the Rocky Mountains, the Cascade Mountains, and the southern Andes, as well as the isolated tropical peaks such as Mount Kilimanjaro in Africa, show some of the largest proportional glacial disadvantages.
The mass balance of glaciers is the major determinant of glacier health. If the amount of frozen precipitation in the accumulated zone exceeds the amount of glacial ice lost by melting or in the ablation zone, the glacier will progress; if accumulation is less than ablation, glaciers will retreat. The reverse glacier will have a negative mass balance, and if they do not find a balance between accumulation and ablation, it will eventually disappear.
The Little Ice Age is a period from about 1550 to 1850 when the world experiences a relatively cooler temperature than it is today. Further, until about 1940, glaciers around the world retreat as the climate warms substantially. The glacial cracks slowed and even reversed temporarily, in many cases, between 1950 and 1980 when global temperatures cooled slightly. Since 1980, significant global warming has caused glacial retreats to rapidly spread everywhere, so much so that some glaciers have disappeared altogether, and the existence of many remaining glaciers is threatened. In locations such as the Andes in South America and the Himalayas in Asia, the demise of glaciers in the region has the potential to affect water supplies in these areas.
The retreat of mountain glaciers, especially in western North America, Asia, the Alps and the tropics and subtropics of South America, Africa and Indonesia, has provided evidence of global temperatures since the late 19th century. The acceleration of the level of decline since 1995 Glacier Greenland's main outlet and the West Antarctic ice sheet may show an increase in sea level, which will affect coastal areas.
Video Retreat of glaciers since 1850
Neraca massa gletser
The mass balance, or the difference between accumulation and ablation (fusion and sublimation), of glaciers is critical to its survival. Climate change can cause variations in temperature and snowfall, resulting in changes in the mass balance. A glacier with continuous negative balance loses balance and retreat. A sustained positive balance is also out of equilibrium and will advance to rebuild equilibrium. Today, almost all glaciers have a negative and reverse mass balance.
A glacier crack causes the loss of lowlands on the glacier. Because of the higher elevation is colder, the loss of the lower part reduces the overall ablation, thereby improving the mass balance and potentially rebuilding the balance. If the mass balance of a significant portion of the glacier accumulation zone is negative, it is in disequilibrium with the climate and will melt without a colder climate and/or increase in frozen rainfall.
Methods for measuring backward include staking terminal locations, global position mapping, air mapping and altimetry lasers. The main symptom of disequilibrium is depletion throughout the entire length of the glacier. This indicates reduced accumulated zones. The result is a marginal recession from the accumulated zone margin, not just from the terminus. As a result, glaciers no longer have a consistent zone of accumulation and no accumulation zones can not survive. For example, Easton Glacier in Washington state, the US is likely to shrink by half its size but at a slowing and stable rate of reduction to that size despite warmer temperatures for decades. However, Grinnell Glacier in Montana, USA will shrink at an increasingly high rate until it disappears. The difference is that the top of Easton Glacier remains healthy and snow-covered, while the top of Grinnell Glacier is naked, melting and thinning. Small glaciers with minimum altitude ranges are most likely to fall into disequilibrium with climates.
Maps Retreat of glaciers since 1850
Middle latitude glacier
Middle-latitude glaciers are located between the Tropic of Cancer and the Arctic Circle, or between the Tropic of Capricorn and the Antarctic Circle. Both of these areas support glacier ice from mountain glaciers, glacier valleys, and even smaller ice sheets, which are usually located in higher mountain areas. All located in the mountains, especially the Himalayas; Alps; Pyrenees; The Rocky Mountains and the Pacific Coast in North America; Andean Patagonian in South America; and mountains in New Zealand. Glaciers at these latitudes are wider and tend to be larger in mass closer to the polar regions. They are the most studied for the last 150 years. As examples lie in tropical zones, almost all glaciers in the mid-latitudes are in a state of negative and reverse mass balance.
Northern Hemisphere - Eurasia
Europe
In France, all six major glaciers in the country are retreating. At Mont Blanc, the highest peak in the Alps, ArgentiÃÆ'¨re Glacier has receded 1,150 m (3,770 ft) since 1870. Other Mont Blanc glaciers have also been retreated, including Mer de Glace, which is the largest glacier. in France at 12 km (7.5 mi) in length but retreated 500 m (1,600 ft) between 1994 and 2008. Glaciers have retreated 2,300 m (7,500 ft) from the end of the Little Ice Age. The Glacier Bossons were once extended from the top of Mont Blanc at 4,807 m (15,771 ft) to a height of 1,050 m (3,440 ft) in 1900. In 2008 Bossons Glacier has retreated to a point that is 1,400 m (4,600Ã, ft) above sea level.
Other researchers have found that glaciers in the Alps seem to retreat at a faster rate than a few decades ago. In a paper published in 2009 by the University of Zurich, a Swiss glacier survey of 89 glaciers found 76 retreating, 5 stationary and 8 moving forward from where they were in 1973. The Trift Glacier has the largest recorded retreat, losing 350 m ( 1.150). Ã, ft) length between 2003 and 2005. Grosser Aletsch glacier is the largest glacier in Switzerland and has been studied since the late 19th century. The Aletsch glacier retreated 2.8 km (1.7 million) from 1880 to 2009. This retreat rate has also increased since 1980, by 30%, or 800 m (2,600 ft), of the total setback that occurred in the last 20% of time period.
Glacier Morteratsch in Switzerland has one of the longest periods of scientific research with annual measurements of long glaciers beginning in 1878. The overall retreat from 1878 to 1998 was 2 km (1.2 million) with an average annual retreat rate of approximately 17 m (56 feet) per year. This long-term average is markedly surpassed in recent years with glaciers receding 30 m (98 ft) per year during the period between 1999-2005. Similarly, from glaciers in the Italian Alps, only about a third retreated in 1980, whereas in 1999, 89% of these glaciers retreated. In 2005, the Italian Glacier Commission found that 123 glaciers in Lombardy retreated. A random study of Sforzellina Glaciers in the Italian Alps shows that the rate of decline from 2002 to 2006 was much higher than in 35 years earlier. To study glaciers located in the mountains of Lombardy, the researchers compared a series of aerial and soil photographs taken from the 1950s through the early 21st century and concluded that between 1954-2003 the smallest glaciers found there lost more than half of their glaciers. area. Repetition of glaciers in the Alps shows that there has been a significant retreat since the study began.
Although Alpine glaciers have received more attention from glaciologists than in other regions of Europe, studies show that glaciers in northern Europe are also retreating. Since the end of World War II, StorglaciÃÆ'¤ren in Sweden has undergone the longest continuous mass balance study in the world conducted from Tarfala research station. In the Kebnekaise Mountains in northern Sweden, a study of 16 glaciers between 1990 and 2001 found that 14 glaciers retreated, one moving forward and one stable. In Norway, glacial studies have been conducted since the early 19th century, with systematic surveys conducted regularly since the 1990s. The terrestrial glaciers have generally negative mass balance, where during the 1990s, marine glaciers showed a positive and sophisticated mass balance. Maritime progression has been associated with heavy snowfall in the period 1989-1995. However, the decline in snow since the cause of most Norwegian glaciers has declined significantly. A survey of 31 Norwegian glaciers in 2010 showed that 27 people were retreating, one unchanged and three progressing. Similarly, in 2013, of 33 Norwegian glaciers surveyed, 26 were retreating, four indicated no change and three advanced.
The Engabreen glacier in Norway, Svartisen's glacier ice cap, has some progress in the 20th century, although it retreated 200 m between 1999 and 2014. The Brenndalsbreen glacier retreated 56 m (184 ft) between 2000 and 2014, while RembesdalsskÃÆ'  ¥ ka glacier , which has retreated 2 km (1.2 million) since the end of the Small Ice Age, retreated 200 m (660 ft) between 1997-2007. The Briksdalsbreen glacier retreated 230Ã, m (750Ã, ft) between 1996 and 2004 with 130Ã,m (430Ã, ft) of that in the final year of the study; the largest annual retreat recorded on the glacier since the study began there in 1900. This figure was exceeded in 2006 with five glaciers retreating more than 100 m (330 ft) from fall 2005 to autumn 2006. Four outlets of ice cap Jostedalsbreen , the largest ice body in the European continent, Kjenndalsbreen, Brenndalsbreen, Briksdalsbreen and Bergsetbreen have frontal retreats over 100 m (330 ft). Overall, from 1999 to 2005, Briksdalsbreen retreated 336 meters (1,102 feet). GrÃÆ'  ¥ fjellsbrea, the Folgefonna ice glacier, has a setback of nearly 100 m (330 ft).
In the Spanish Pyrenees, recent studies have shown significant losses in the levels and volumes of massive Maladeta glaciers over the period 1981-2005. This includes a reduction in the area of ​​35.7%, from 2.41 km 2 (600 acres) to 1.55 km 2 (380 acres), total ice volume loss from 0.0137 km 3 (0.0033Ã, cuÃ, mi) and an average increase in the glacial altitude of 43.5 m (143Ã, ft). For the Pyrenees as a whole 50-60% of glacial areas have been lost since 1991. Glaciers Balaitus, Perdigurero and La Munia have been lost in this period. Glacier Monte Perdido has shrunk from 90 hectares to 40 hectares.
As an initial cause for retreating glaciers in the mountains since 1850, the decrease in albedo glaciers, caused by industrial black carbon could be identified. According to a report, this might accelerate the acceleration of glaciers in Europe that might otherwise continue to grow until about 1910.
Siberia and the Russian Far East
Siberia is usually classified as a polar region, due to winter climatic droughts and only has glaciers in the high Altai Mountains, the Verkhoyansk Range, the Cherskiy Range and the Suntar-Khayata Range, plus the possibility of some small glaciers in the range near Lake Baikal, which have never been monitored and possibly has completely disappeared since 1989. Between 1952 and 2006, the glaciers found in the Acre Basin region shrank by 7.2 percent. This shrinkage occurs mainly in the glacier ablation zone, with a few hundred meter recession observed for some glaciers. The Altai region also experienced an overall temperature increase of 1.2 degrees Celsius in the last 120 years according to reports from 2006, with most of the increase taking place since the late 20th century.
In the Russian Far East which is more maritime and generally wet, Kamchatka, exposed during winter to moisture from Low Aleutian, has a much wider glaciation of about 906 km 2 (350 square meters) with 448 known glaciers as 2010. Although winter snowfall generally weighs and cold summer temperatures, high summer rainfall in the more southern Kuril Islands and Sakhalin in historic times melts has too high a level to balance the positive mass even at the highest peaks. In the glaciers of the Chukotskiy Alps are many small, but the level of glaciation, though larger than the far west, is much smaller than in Kamchatka, amounting to about 300 square kilometers (120 sq. M).
Details about the retreat of the Far Eastern Siberian and Russian glaciers are less than in most other glacial regions of the world. There are several reasons for this, the main being that since the collapse of Communism there has been a substantial reduction in the number of monitoring stations. Another factor is that in Verkhoyansk and Cherskiy Ranges, glaciers were considered absent before it was discovered in the 1940s, while in Kamchatka ultra-remote and Chukotka, although the presence of glaciers had been known before, monitoring of their size did not exist early. from the end of World War II. Nevertheless, the available records show a common crack of all glaciers in the Altai Mountains with the exception of volcano glaciers in Kamchatka. Sakha glaciers, covering an area of ​​seventy square kilometers, have shrunk by about 28 percent since 1945 reaching a few percent every year in some places, while in the Altai and Chukotkan and non-volcanic mountains of Kamchatka, the shrinkage is much greater.
Himalayas and Central Asia
Himalayas and other mountain chains in Central Asia support a large glacial region. An estimated 15,000 glaciers can be found in the larger Himalayas, with twice the amount in the range of Hindu Kush and Karakoram and Tien Shan, and comprise the largest glacial region beyond the poles. This glacier provides an important water supply to dry countries such as Mongolia, western China, Pakistan, Afghanistan and India. Like glaciers around the world, people from the greater Himalayan region are experiencing mass decline, and researchers claim that between the early 1970s and early 2000s, there was a 9% reduction in ice mass. Temperature changes have led to the melting and formation and expansion of glacial lakes that could lead to an increase in the number of glacial lake overflows (GLOFs). If current trends persist, ice mass will decrease gradually, and will affect the availability of water resources, although water loss is not expected to cause problems for decades.
In the Wakhan Corridor of Afghanistan 28 of 30 glaciers were examined with significant retreat between 1976-2003, with an average retreat of 11 m (36 ft) per year. One of these glaciers, the Zemestan Glacier, retreated 460 m (1,510 ft) during this period, not quite 10% of its 5.2 km (3.2 miles) in length. In examining 612 glaciers in China between 1950 and 1970, 53% of studied glaciers retreated. After 1990, 95% of these glaciers were measured to retreat, indicating that these glacier cracks became more widespread. The glaciers in the Himalayas region of Mount Everest are all in retreat. The Rongbuk glacier, which dries the northern side of Mount Everest to Tibet, has retreated 20 m (66 ft) per year. In the Khumbu region of Nepal along the main Himalayan front of the 15 glaciers examined from 1976 to 2007 all retreat significantly and the average retreat is 28 m (92 ft) per year. The most famous of these, Khumbu Glacier, retreated at a rate of 18 m (59 ft) per year from 1976-2007. In India, Gangotri Glacier retreated 1,147 m (3,763 ft) between 1936 and 1996 with 850 m (2,790 ft) of decline that occurred in the last 25 years of the 20th century. However, the glacier is still more than 30 km (19 mi) long. In Sikkim, 26 glaciers examined between 1976 and 2005 withdrew an average of 13.02 m (42.7 ft) per year. Overall, the studied glaciers in the Greater Himalayan region have decreased on average between 18 and 20 m (59 and 66 ft) each year. The only areas in the Greater Himalayas that have seen glacial progress are in the Karakoram Range and only in the highest elevation glaciers, but this has been linked to the possibility of increased rainfall as well as to correlated glacial waves, where glacier tongues advanced due to pressure build up from snow and ice accumulation further up the glacier. Between 1997 and 2001, the 68 km (42 mile) Biafo glacier thickened glaciers mid-10 to 25 m (33 to 82 feet), but did not go.
With the retreat of glaciers in the Himalayas, a number of glacial lakes have been created. A growing concern is the potential for GLOF researchers to estimate 21 glacial lakes in Nepal and 24 in Bhutan pose a danger to the human population if their terminal moraines fail. One of the glacial lakes identified as potentially dangerous is Raphstreng Tsho in Bhutan, which measures 1.6 km (0.99 miles) long, 0.96 km (0.60 miles) and a depth of 80 m (260 feet) in 1986. By 1995 the lake had swelled. with a length of 1.94 km (1.21 mi), 1.13 km (0.70 miles) wide and 107 m (351 feet) deep. In 1994 a GLOF from Luggye Tsho, a glacial lake adjacent to Raphstreng Tsho, killed 23 people downstream.
Glaciers in the Ak-shirak Range in Kyrgyzstan suffered slight losses between 1943 and 1977 and the loss of the remaining 20% ​​of their mass between 1977 and 2001. In the Tien Shan mountains, where Kyrgyzstan shared with China and Kazakhstan, studies in the northern regions of the mountains shows that the glaciers that help supply water to this dry region, lost nearly 2 km 3 (0.48Ã, cuÃ, mi) of ice per year between 1955 and 2000. The Oxford University Research also reported that on average 1.28% of this glacier volume has been lost annually between 1974 and 1990.
The Pamir Mountains, located mainly in Tajikistan, have about eight thousand glaciers, many of which are in a state of general retreat. During the 20th century, Tajikistan's glaciers lost ice <20> km (4.8Ã, cuÃ, mi). The 70 km (43 mi) Fedchenko glacier, which is the largest in Tajikistan and the largest non-polar glacier on Earth, retreated 1 km (0.62 mi) between 1933 and 2006, and lost 44 km 2 Northern Hemisphere - North America
North American glaciers are mainly located along the ridges of the Rocky Mountains in the United States and Canada, and the Pacific Coast Coast extends from northern California to Alaska. While Greenland is geologically linked to North America, it is also part of the Arctic region. Apart from some tidewater glaciers such as Taku Glacier, in the early stages of their common tidewater glacier cycle along the Alaska coast, almost all of them in North America are in retreat. This number has grown considerably since around 1980, and overall every decade has since experienced a greater retention rate than before. There are also small residual glaciers scattered throughout the Sierra Nevada mountains in California and Nevada.
Ranged Range
The Cascade Mountains in western North America stretch from southern British Columbia in Canada to northern California. Except for Alaska, about half of the glacial regions in the US are contained in over 700 glaciers in the North Cascades, some of them located between the Canadian-US border and I-90 in central Washington. It contains as much water as it is found in all lakes and reservoirs in the rest of the country, and provides plenty of streams and streams in the dry summer months, approximately 870,000 m 3 (1,140,000 Ã, cuÃ, yd).
Recently in 1975 many North Cascade glaciers advanced due to cooler weather and increased rainfall from 1944 to 1976. In 1987, the Northern Cascade glacier retreated and its speed increased every decade since the mid-1970s. Between 1984 and 2005 the North Cascade glacier lost an average thickness of more than 12.5 meters (41Ã, ft) and 20-40 percent of its volume.
The glaciologist who studied North Cascades found that all 47 monitored glaciers are receding while four glaciers - Spider Glacier, Lewis Glacier, Glacier Lake Glacier and David Glacier - have disappeared altogether since 1985. Glacier Peak Glacier (Glacier Peak Glacier) is a very dramatic example. The glacier area shrank from 3.1 km 2 (1,2Ã, sqÃ, mi) in 1958 to 0.9 km 2 (0.35Ã, sqÃ, mi) in 2002. Between 1850 and 1950, the Boulder Glacier on the southeast side of Mount Baker retreated 8,700 feet (2,700 m). William Long of the United States Forest Service observed glaciers beginning to accelerate in winter in 1953. This was followed by 743 meters (2,238 feet) in 1979. Glaciers once again retreated 450 m (1,480 ft) from 1987 to 2005 , leaving a barren field behind. This retreat has occurred during periods of reduced winter snow and higher summer temperatures. In this Cascades region, winter snowpack has dropped 25% since 1946, and summer temperatures have increased by 0.7 Â ° C (1.2 Â ° F) during the same period. The reduced snowpack has occurred despite a small increase in the rainy season - thus, this reflects the warm winter temperatures that lead to rainfall and melt on glaciers even during winter. In 2005, 67% of the observed Northern Cascade glaciers were in disequilibrium and would not survive the current climate continuity. This glacier will eventually disappear unless the temperature falls and the frozen rainfall increases. The remaining glaciers are expected to be stable, unless the climate continues to warm, but will be considerably reduced in size.
AS. Rocky Mountains
On slopes sheltered from the highest peak of Glacier National Park in Montana, the eponymous glaciers are rapidly diminishing. The area of ​​each glacier has been mapped for decades by the National Park Service and the US Geological Survey. Comparing photographs from the mid-19th century with contemporary images provides ample evidence that they have been retreating significantly since 1850. Repetition of photography because it clearly shows that glaciers like the Grinnell Glacier are all retreating. The larger glacier is now roughly a third of its previous size when first studied in 1850, and many of the smaller glaciers have disappeared completely. Only 27% of the 99Ã, km 2 (38Ã, sqÃ, mi) of Glacier National Park covered by glaciers in 1850 remained closed by 1993. Researchers believe that by 2030, most of the glacial ice in the Park National Glaciers will disappear unless current climatic patterns reverse their path. Grinnell Glacier is just one of the many glaciers in Glacier National Park that have been well documented by photographs for decades. The photographs below clearly show the retreat of the glacier since 1938.
The semi-arid climate of Wyoming is still capable of supporting about a dozen small glaciers in Grand Teton National Park, all of which show evidence of decline over the past 50 years. The Glacier schoolroom is located a little southwest of the Grand Teton is one of the more easily accessible glaciers in the park and is expected to disappear by 2025. Research between 1950 and 1999 shows that glaciers in the Bridger-Teton National Forest and Shoshone National Forest on the Wind River Range shrink more than a third of their size during that period. The photographs show that the glaciers are currently only half the size when first photographed in the late 1890s. Research has also shown that glacial cracks are proportionately larger in the 1990s than in any other decade over the last 100 years. Gannett Glacier on the northeastern slope of Gannett Peak is the largest single glacier in the Rocky Mountains in southern Canada. It has been reported to lose more than 50% of its volume since 1920, with nearly half of its losses since 1980. Glaciologists believe the remaining glaciers in Wyoming will disappear by the middle of the 21st century if current climatic patterns continue.
Canadian Rocky Mountains and Coast Mountains and Columbia
In the Canadian Rockies, glaciers are generally larger and wider than in the south in the Rocky Mountains. One of the more accessible in the Canadian Rockies is Glacier Athabasca, which is a glacier outlet of 325 km <2> (125Ã, sqÃ, mi) Columbia Icefield. The Athabasca Glacier has retreated 1,500 m (4,900 ft) since the late 19th century. The pullback rate has increased since 1980, after a slow retreat period from 1950 to 1980. The Peyto glacier in Alberta covers an area of ​​about 12 km <2> (4.6 m²), and retreats rapidly. during the first half of the 20th century, stabilized in 1966, and again shrunk in 1976. The Illecillewaet glacier in the British Columbia (Canada) Glacier National Park, part of the Selkirk Mountains (west of the Rockies) has retreated 2 km (1.2 mi) was photographed in 1887.
In the Garibaldi Provincial Park in the southwest of British Columbia more than 505 km <2>/(195Ã, sqÃ, mi), or 26%, from the park, covered by ice glaciers in the early 18th century. The ice cover dropped to 297 km <2>/> (115Ã, sqÃ, mi) in 1987-1988 and up to 245 °, km 2 (95Ã, sqÃ, mi) in 2005, 50 % of 1850 regions. 50 km <2> (19Ã, sqÃ, mi) losses in the past 20 years coincide with the negative mass balance in the region. During this period all nine glaciers examined have retreated significantly.
Alaska
There are thousands of glaciers in Alaska but only a few are named. The Columbia Glacier near Valdez in Prince William Sound has retreated 15 km (9.3 miles) in the last 25 years. The partially entangled iceberg caused the Exxon Valdez oil spill, when the tanker changed direction to avoid the ends of the ice. The Valdez glacier is in the same region, and although it does not give birth, it has also retreated significantly. "A 2005 air survey of coastal Alaska coastal glaciers identified more than a dozen glaciers, many glaciers and glaciers, including the rapidly declining Grand Plateau, Alsek, Bear and Excelsior Glaciers, of which 2,000 glaciers were observed, 99% retreated." Icy Bay in Alaska is fed by three large glaciers - Guyot, Yahtse, and the Tyndall Glacier - all of which are losing length and thickness and, consequently, losing the area. Tyndall Glacier became separated from the Guyot Glacier which retreated in 1960 and has retreated 24 km (15 miles) since, on average over 500 m (1,600 feet) per year.
The Juneau Icefield Research Program has been monitoring the Juneau Icefield glacier outlet since 1946. On the western side of the ice field, the tip of Mendenhall Glacier, which flows into the outskirts of Juneau, Alaska, has retreated 580 m (1,900 ft). Of the nineteen glaciers in Juneau Icefield, eighteen retreated, and another, Taku Glacier, progressed. Eleven glaciers have retreated more than 1 km (0.62 miles) since 1948 - Antler Glacier, 5.4 km (3.4 miles); Gilkey Glacier, 3.5 km (2.2 miles); Norris Glacier, 1,1Ã, km (0.68Ã, mi) and Lemon Creek Glacier, 1.5Ã, km (0.93Ã, mi). The Taku glacier has advanced since at least 1890, when the naturalist John Muir observed the huge front of the iceberg. By 1948 the adjacent fjords had been filled, and glaciers were no longer childbearing and were able to continue their progress. In 2005 the glacier was only 1.5 km (0.93 miles) from reaching Taku Point and blocking Taku Inlet. The progress of Taku Glacier averaged 17 m (56 ft) per year between 1988 and 2005. The mass balance was very positive for the 1946-88 period that encouraged progress; However, since 1988, the mass balance has been slightly negative, which should in the future slow down the progress of this great glacier.
Long-term mass balance records from Lemon Creek Glacier in Alaska show a slightly decreased mass balance over time. The average annual balance for this glacier is -0.23 m (0.75 ft) annually during the period from 1957 to 1976. The average annual balance has been negatively averaged -1.04 m (3.4 ft) per year from 1990 to 2005 Repeat glacier altimetry, or altitude measurements, for Alaska's 67 glaciers found the level of thinning has increased by more than one factor two when comparing the period from 1950 to 1995 (0.7 m (2.3 ft) per year) and 1995 to 2001 (1.8 m (5.9 ft) per year). This is a systemic trend with a loss of mass equal to the loss of thickness, which leads to increased retention - not only glacier retreat, but also become thinner. In the Denali National Park, all glaciers are monitored backwards, with an average retreat of 20 m (66 ft) per year. The Terminus of the Toklat Glacier has retreated 26 m (85 ft) per year and the Muldrow Glacier has thinned 20 m (66 ft) since 1979. Well documented in Alaska is a surging glacier that has been known to rapidly advance, even as much as 100 m (330 ft) per day. Variety, Black Rapids, Muldrow, Susitna and Yanert are examples of the soaring glaciers in Alaska that have made rapid progress in the past. These glaciers are all retreating in their entirety, punctuated by a brief period of progress.
Southern Hemisphere
Andes and Tierra del Fuego
A large area of ​​population around the central and southern parts of the Andes of Argentina and Chile is in a dry region that depends on the water supply of melting glaciers. Water from glaciers also supplies rivers that in some cases have been dammed for hydroelectric power. Some researchers believe that by 2030, many of the largest ice sheets at the highest Andes will disappear if current climate trends continue. In Patagonia on the southern tip of the continent, large ice caps have retreated 1 km (0.62 miles) since the early 1990s and 10 km (6.2 miles) since the late 19th century. It has also been observed that Patagonia glaciers recede at a faster rate than in other regions of the world. The Northern Patagonian Ice Field lost 93a, km 2 (36Ã, sqÃ, mi) of the glacier area during the years between 1945 and 1975, and 174Ã, km 2 (67Ã, sqÃ, mi) from 1975 to 1996, which suggests that retreat levels are increasing. This represents a loss of 8% of the ice field, with all glaciers experiencing significant deterioration. The Southern Patagonia Ice Field has shown a general trend of retreat on 42 glaciers, while four glaciers are in equilibrium and two advanced during the years between 1944 and 1986. The biggest retreat was at O'Higgins Glacier, which during the period 1896-1995 retreated 14, 6 km (9.1 mi). Perito Moreno glacier is 30 km (19 miles) long and is the mainstream glacier of the Patagonian ice sheet, and the most visited glacier in Patagonia. Perito Moreno glaciers are in equilibrium, but have experienced frequent oscillations in the period 1947-96, with a net profit of 4.1 km (2.5 mi). This glacier has grown since 1947, and has been essentially stable since 1992. Perito Moreno glacier is one of three glaciers in Patagonia known to have progressed, compared to some other glaciers in retreats. Two major glaciers from Southern Patagonia Icefield to the north of Moreno, Upsala and Viedma Glacier have retreated 4.6 km (2.9 miles) in 21 years and 1 km (0.62 miles) in 13 years each. In Aconcagua River Valley, retreating glaciers have resulted in a 20% loss in the glacier area, down from 151 km 2 (58 m²) to 121 km 2 (47 m²) mi). Marinelli's glacier at Tierra del Fuego has been retreating since at least 1960 to 2008.
Oceania
In New Zealand, mountain glaciers have been in general decline since 1890, accelerating since the 1920s. Most have been definitely thin and diminished in size, and snow accumulation zones have increased as the 20th century took place. Between 1971-75 Ivory glaciers recede 30 m (98 ft) from the glacial tip, and about 26% of its surface area is lost. Since 1980 many small glacial lakes have formed behind the new terminal moraines of some of these glaciers. Glaciers like Classen, Godley and Douglas now all have new glacial lakes beneath their terminal locations due to glacial cracks over the last 20 years. Satellite images show that the lake is growing. There is a significant and sustained loss of ice volume on New Zealand's largest glaciers, including Tasman, Ivory, Classen, Mueller, Maud, Hooker, Gray, Godley, Ramsay, Murchison, Therma, Volta and Douglas Glaciers. The retreat of the glacier is characterized by the widespread proglacial lake and the depletion of the terminus region. The loss in the Southern Alps total ice volume from 1976-2014 was 34% of the total.
Some glaciers, especially the glorified Fox and the much-visited Franz Josef on the West Coast of New Zealand, have evolved periodically, especially during the 1990s, but this scale of progress is small when compared to 20th-century retreats. Both are more than 2.5 km (1.6 mi) shorter than a century ago. This large, fast-flowing glacier lies on a steep slope, highly reactive to small changes in the mass balance. Several years of conditions favoring the progress of glaciers, such as the more west wind and the increase of snowfall, were rapidly echoed in the same progress, followed by an equally rapid decline when the favorable conditions were over. Glaciers that have advanced in several locations in New Zealand have done so because of temporary local weather conditions, which have brought more rain and cloudy, colder summers since 2002.
Tropical glaciers
Tropical glaciers lie between the Tropic of Cancer and the Tropic of Capricorn, in an area located 23 Â ° 26? 22? north or south of the equator. Strictly speaking, tropical glaciers are located in tropical astronomy; regions where annual temperature variations are less than daily variations, and are within the oscillation area of ​​the Intertropical Convergence Zone.
Tropical glaciers are the most uncommon of all glaciers for various reasons. First, the region is the warmest part of the planet. Secondly, seasonal changes are minimal with warm temperatures throughout the year, resulting in a lack of cooler winters where snow and ice can accumulate. Third, some higher mountains exist in areas where there is enough cold air for glacier formation. Overall, tropical glaciers are smaller than those found elsewhere and are the most likely glaciers to show rapid response to changes in climatic patterns. A slight increase in the temperature of a few degrees can have a direct and bad effect on tropical glaciers.
Near the Equator, ice is still found in East Africa, the Andes in South America and New Guinea. The retreat of the equatorial glacier has been documented through maps and photographs covering the period from the late 1800s to almost now. 99.64% of tropical glaciers are in the Andes Mountains of South America, 0.25% on African glaciers in Rwenzori, Mount Kenya and Kilimanjaro, and 0.11% in Irian Jaya region in New Guinea.
Africa
Almost all Africa is in tropical and subtropical climate zones. The glacier is found only in two separate ranges and the Ruwenzori Range. Kilimanjaro, at 5,895 m (19,341 ft), is the highest peak on the continent. Since 1912, the glacier cover on the peak of Kilimanjaro appears to have been reduced by 75%, and the volume of glacial ice is now 80% lower than a century ago due to cracking and thinning. In a 14-year period from 1984 to 1998, a section of glaciers at the top of the mountain receded 300 m (980 ft). A 2002 study determined that if current conditions continue, glaciers above Kilimanjaro will disappear sometime between 2015 and 2020. The March 2005 report shows that almost no glacial ice is left on the mountain, and that is the first time in 11,000 years that is barren. the soil has been exposed on the part of the peak. The researchers reported that the Kilimanjaro glacier climb was caused by a combination of increased sublimation and snowfall.
The FurtwÃÆ'¤ngler glacier is located near the summit of Kilimanjaro. Between 1976 and 2000, the FurtwÃÆ'¤ngler Glacier area was cut in half, from 113,000 m 2 (1.220.000 sqÃ, ft) to 60,000 m 2 (650,000 Sq ft). During fieldwork conducted in early 2006, scientists discovered a large hole near the center of the glacier. This hole, which extends through the remaining glacier thickness of up to 6 m (20 ft) to the underlying rock, is expected to grow and split the glaciers in two in 2007.
To the north of Kilimanjaro lies Mount Kenya, which at 5,199 m (17,057 ft) is the second highest mountain on the continent. Mount Kenya has a number of small glaciers that have lost at least 45% of their mass since the mid-20th century. According to a study compiled by the US Geological Survey (USGS), there were eighteen glaciers at the top of Mount Kenya in 1900, and in 1986 only eleven were left. The total area covered by glaciers was 1.6 km 2 (0.62Ã, sqÃ, mi) in 1900, but in 2000 only about 25%, or 0.4 km 2 (0.15Ã, sqÃ, mi) remain. To the west of Mount Kilimanjaro and Kenya, Range Ruwenzori rose to 5,109 m (16,762 ft). Photo evidence shows marked reductions in glacial covered areas over the last century. In a 35-year period between 1955 and 1990, glaciers in the Rwenzori Mountains receded about 40%. It is hoped that due to its proximity to the strong humidity of the Congo region, the glaciers in Ruwenzori Range can recede at a slower rate than in Kilimanjaro or in Kenya.
South America
A study by glaciologists from two small glaciers in South America revealed another retreat. More than 80% of all glacial ice in the northern Andes are concentrated in the highest peaks in a small plain of about 1 km 2 (0.39 sqM) in size. Observations from 1992 to 1998 on the Chacaltaya Glacier in Bolivia and the Antizana Glacier in Ecuador show that between 0.6 m (2.0 ft) and 1.9 m (6.2 m) of ice is lost per year on each glacier. The number for Chacaltaya shows a loss of 67% of the volume and 40% of its thickness over the same period. Chacaltaya Glacier has lost 90% of its mass since 1940 and is expected to disappear altogether between 2010 and 2015. Antizana is also reported to have lost 40% of its surface area between 1979 and 2007. Research also shows that since the mid-1980s, the retreat rates for both glaciers this has increased. In Colombia, the top glacier Nevado del Ruiz has lost more than half of their territory in the last 40 years. Further south in Peru, the Andes are at higher altitudes overall, and there are about 722 glaciers covering an area of ​​723 km 2 (279 sqÃ, mi).
Research in this region is less extensive but shows an overall decline of 7% between 1977 and 1983. Quelccaya Ice Cap is the second largest tropical ice layer in the world after the Coropuna ice cap, and all glacier outlets of the ice sheet are retreating. In the case of Qori Kalis Glacier, which is one of the Quelccayas outlet glaciers, the rate of decline has reached 155 m (509 ft) per year during the three-year period 1995 to 1998. The melting ice has formed a large lake. in front of the glacier since 1983, and the vacant lot has been open for the first time in thousands of years.
Oceania
The Janis 1620 Jan Carstensz glacier report covering the equatorial mountains of New Guinea was initially filled with ridicule, but by the early 20th century, at least five subranges from the Maoke Mountains (meaning "Snow Mountains") were still found to be covered in large ice. hat. Because of the island's location within the tropical zone, there is little or no seasonal temperature variation. Tropical locations have stable predictable levels of rain and snow, as well as cloud cover throughout the year, and there has been no noticeable change in the amount of moisture that has fallen during the 20th century.
In 1913, 4,550 m (14,930 ft) tall Prins Hendrik (now Yamin Peak) was named and reported to have "eternal snow", but this observation was never repeated. The 4,720 m (15,490 feet) ice cap Wilhelmina Peaks, which reached under 4,400 m (14,400 feet) in 1909, disappeared between 1939 and 1963. The Mandala/Juliana ice cap disappeared in the 1990s. and the Idenburg glacier at Ngga Pilimsit dried up in 2003. This leaves only the remains of a continuous escape in Papua's highest mountain, Mount Carstensz with a peak of 4,884 m (16,024 ft) High Jaya peak, which is estimated to have an area of ​​20 km 2 (7.7Ã, sqÃ, mi) in 1850.
For this mountain there is photographic evidence of a massive glacial retreat because the area was first explored extensively by aircraft in 1936 in preparation for the first peak climb (see for example [1]). Between that time and 2010, the mountain lost 80 percent of its ice - two-thirds of it since another scientific expedition in the 1970s. Research that between 1973 and 1976 showed glacier retreat for Meren Glacier of 200 m (660 ft) while Carstensz Glacier lost 50 m (160 ft). The Northwall Firn, the largest remaining ice sheet ever in Puncak Jaya, has been separated into two separate glaciers after 1942. IKONOS satellite images of the New Guinean glacier indicate that in 2002 only 2.1 km 2 (0.81Ã, sqÃ, mi) fixed glacial areas, that within two years from 2000 to 2002, the East Northwall Firn has lost 4.5%, West Northwall Firn 19.4% and Carstensz 6.8% of the glacial mass them, and sometimes between 1994 and 2000, the Meren Glacier has disappeared altogether. An expedition to the glaciers remaining in Puncak Jaya in 2010 found that glacier ice there is about 32 meters (105 feet thick) and thins at a rate of 7 meters (23 feet) each year. At that level, the remaining glaciers are expected to last only until 2015.
Polar region
Despite the proximity and significance of human populations, glacier mountains and glaciers of tropical and middle latitudes are only a fraction of glacial ice on Earth. Approximately 99% of all freshwater ice is in the great ice sheets of Antarctic and Greenland Antarctic and Subcut. Continuous continuous layer of this scale, 3 km (1.9 mi) or thicker, cover most of the soil mass of polar and subpolar. Like a river flowing from a huge lake, many ice channels out carry ice from the edge of the ice to the ocean.
Iceland
The northern Atlantic island of Iceland is home to VatnajÃÆ'¶kull, which is Europe's largest ice cap. The BreiÃÆ' Â ° amerkurjÃÆ'¶kull glacier is one of the VatnajÃÆ'¶kull outlet glaciers, and recedes 2 km (1.2Ã, mi) between 1973 and 2004. At the beginning of the 20th century, BreiÃÆ'Â Â ° amerkurjÃÆ'¶kull extended to 250 m ( 820Ã, ft) oceans, but by 2004 the terminal had retreated 3 km (1.9 mi) farther inland. This glacier retreat exposes the fast-growing lagoon, JÃÆ'¶kulsÃÆ'¡rlÃÆ'³n, which is filled with icebergs that are born from the front. JÃÆ'¶kulsÃÆ'¡rlÃÆ'³n has a depth of 110 m (360 ft) and is almost twice its size between 1994 and 2004. Iceland glacier mass-balance measurements show the balance of positive and negative glaciers alternating during the period 1987-95, but the mass balance has been dominated negative since. In the HofsjÃÆ'¶kull ice cap, the mass balance has been negative every year from 1995-2005.
Most of the Icelandic glaciers retreated rapidly during the warm decades of 1930-1960, slowing as the climate cooled over the next decade, and began to increase after 1970. The rate of progress peaked in the 1980s, after which it slowed down to around 1990. As a consequence of the warming fast from the climate that has occurred since the mid-1980s, most of the glaciers in Iceland began to retreat after 1990, and by 2000 all non-surge monitor glaciers in Iceland were retreating. The average 45 non-corrugated termini is monitored annually by the Icelandic Glaciological Society from 2000-2005.
Canada
The Canadian Arctic Archipelago contains the largest area and volume of Earth's ice on Earth outside Greenland and the Antarctic Ice Sheet and is home to an enormous amount of ice, including Penny and Barnes ice caps on Baffin Island, Bylot Ice Cap on Bylot Island, and Devon Ice Cap on Devon Island. Glaciers in the Arctic Canada approached the equilibrium between 1960 and 2000, losing 23 Gt of ice per year between 1995 and 2000. Since then, the Arctic glaciers have experienced a sharp increase in mass loss in response to warmer summer temperatures, losing 92 Gt per year between 2007 and 2009.
Other studies show that between 1960 and 1999, Ice Cap Devon lost 67Ã, km 3 (16Ã, cuÃ, mi) ice, mainly through thinning. All major glaciers along the eastern edge of the Devon Sea have retreated from 1 km (0.62 miles) to 3 km (1.9 miles) since 1960. On the Hazen Plateau on Ellesmere Island, Simmon Ice Cap has lost 47% of its area since 1959. If current climatic conditions continue, the remaining glacial ice in Hazen Plain will be lost by 2050. On August 13, 2005, the Ayles Ice Shelf broke free of the northern coast of Ellesmere Island. The 66Ã, km 2 (25Ã, sqÃ, mi) ice shelf drifted into the Arctic Ocean. It follows the division of Ward Hunt Ice Shelf in 2002. Ward Hunt has lost 90% of its territory in the last century.
Northern Europe
The Arctic Islands in northern Norway, Finland and Russia all show evidence of retreating glaciers. In the Svalbard archipelago, Spitsbergen Island has many glaciers. Research shows that Hansbreen (Hans Glacier) in Spitsbergen retreated 1.4 km (0.87 miles) from 1936 to 1982 and 400 m (1,300 feet) over a 16-year period from 1982 to 1998. Blomstrandbreen, the glacier at King's Area bay of Spitsbergen, has retreated about 2 km (1.2 miles) in the last 80 years. Since 1960, the average Blomstrandbreen retreat is about 35 m (115 ft) per year, and this average is increased due to the backward acceleration rate since 1995. Similarly, Midre Lovenbreen retreated 200 m (660 ft) between 1977 and 1995. In the Novaya Zemlya archipelago in northern Russia, research shows that in 1952 there were 208.8 km of ice blocks along the coast. In 1993 it has been reduced by 8% to 198 km (123 mi) from the glacier coastline.
Greenland
In Greenland, a glacier crack has been observed in outlet glaciers, resulting in an increase in ice flow rate and destabilization of the ice layer mass balance at the source. The net loss in volumes and sea level contributions of the Greenland Ice Sheet (GIS) has doubled in recent years from 90 km 3 (22Ã, Â ° c) in 1996 to 220 km 3 (53Ã, cuÃ, mi) per year in 2005. The researchers also noted that widespread acceleration affected almost all glaciers south of 70 N in 2005. The period since 2000 has brought back into some very large glaciers has long been stable. Three glaciers studied - Helheim Glacier, Kangerdlugssuaq Glacier, and Jakobshavn IsbrÃÆ'Â| - together account for more than 16% of Greenland Ice sheets. In the case of Helheim Glacier, the researchers used satellite imagery to determine the movement and retreat from the glaciers. Satellite images and aerial photography from the 1950s and 1970s show that the glacier's front remains in the same place for decades. In 2001 the glacier began to retreat rapidly, and by 2005 the glacier had retreated a total of 7.2 km (4.5 mi), accelerating from 20 m (66 ft) per day to 35 m (115 ft) per day during the period.
Jakobshavn IsbrÃÆ'Â| in western Greenland, the main glacier of the Greenland Ice Sheet, has been the fastest moving glacier in the world for the past half century. It has been continuously moving at speeds of more than 24 m (79 ft) per day with a stable terminus since at least 1950. In 2002, a long glacier terminal that floated for 12 km (7.5 mi) entered a rapid retreat phase, with the front ice breaking and floating terminus are destroyed and accelerate to a reverse level of more than 30 m (98 ft) per day. On a shorter time scale, the portion of the main Kangerdlugssuaq Glacier trunk that flows at 15 m (49 ft) per day from 1988 to 2001 was measured to flow at 40 m (130 ft) per day in the summer of 2005. Not only did Kangerdlugssuaq which retreats, it also depletes more than 100 m (330 ft).
The rapid depletion, acceleration and retreat of Helheim glaciers, Jakobshavns, and Kangerdlugssuaq in Greenland, all in close connection with one another, suggest common trigger mechanisms, such as increased surface melting due to regional climate warming or stylistic changes in front of glaciers.. Increased melts leading to glacier base lubrication have been observed causing a slight increase in seasonal velocity and catfish lakes discharge also causing only small short-term acceleration. The significant acceleration recorded on the three largest glaciers begins in front of calving and is deployed inland and is not seasonal in nature. Thus, the major source of accelerated glacier-outlet acceleration observed in Greenland small and large glaciers is driven by dynamic force changes in front of glaciers, not enhanced melt water lubrication. This is called the Jakobshavns Effect by Terence Hughes at the University of Maine in 1986. Indeed, a study published in 2015 topographic topographic glaciers at 3 sites found a cavity, due to subglacial warm water intrusion, which has been identified as a possible dominant force for ablation (surface erosion). Thus, the temperature of the sea controls the runoff of ice sheets in certain locations. The findings also show that the model underestimated the sensitivity of Greenland's glaciers to ocean warming and resulted in runoff of ice sheets. Therefore, without better modeling, new observations indicate that the previous projection of sea level rise from the Greenland Ice Sheet requires upward revision.
Antarctic
Antarctica is very cold and dry. Most of the world's freshwater ice is contained in the sheets. The most dramatic example of a glacier retreat is the loss of most of the Larsen Ice Shelf on the Antarctic Peninsula. The recent collapse of Ice Shelf Wordie, Ice Shelf Prince Gustav, Ice Mueller Shelf, Jones Ice Shelf, Larsen-A and Larsen-B Ice Shelf on the Antarctic Peninsula have increased awareness of how the ice shelf system is dynamic.
The Antarctic Sheet is the largest known single ice mass. It covers nearly 14 million km <2>/> and about 30 million km <3> ice. Approximately 90% of the freshwater surface on the surface of the planet is held in this area and if melt will raise the sea level up to 58 meters. The trend of the average surface temperature of the Antarctic continent is positive and significant at the & gt; 0.05 ° C/decade since 1957.
The Antarctic sheet is divided by the Transantitic Mountains into two unequal pieces known as the Eastern Antarctic ice sheet (EAIS) and the smaller Western Antarctic Ice Sheet (WAIS). EAIS rests on a large mainland but the WAIS bed, in place, is over 2,500 meters below sea level. It will be the seafloor if the ice sheet is not there. WAIS is classified as a sea-based ice sheet, meaning that its bed lies below sea level and its tip flows to a floating ice shelf. The WAIS is limited by Ross Ice Shelf, the Ronne Ice Shelf, and a glacier outlet that flows into the Amundsen Sea.
The ice shelf is unstable when the melted surface occurs, and the collapse of Larsen Ice Shelf is caused by melting summer temperatures that have caused surface melting and the formation of shallow water pools on ice shelves. Larsen Ice Shelf lost 2,500 km 2 (970Ã, sqÃ, mi) from its area from 1995 to 2001. In a 35-day period beginning on 31 January 2002, about 3,250 km 2 (1.250Ã, sqÃ, mi) from the ruined shelves area. The ice shelf is now 40% the size of the previous minimum stable level. By 2015 a study concluded that ice shelf ice remains to be destroyed by the end of the decade, based on faster flow observations and rapid glacier depletion in the area. Jones Ice Shelf has an area of ​​35Ã, km 2 (14Ã, sqÃ, mi) in the 1970s but in 2008 it has disappeared. Wordie Ice Shelf has gone from an area of ​​1,500 km 2 (580Ã, sqÃ, mi) in 1950 to 1,400 km 2 (540Ã, sqÃ, mi) in 2000. Prince Gustav Ice Shelf has gone from an area of ​​1,600 km 2 (620Ã, sqÃ, mi) to 1,100 km 2 (420Ã, sqÃ, mi) in 2008. After losing they reduce the feeder glaciers feeder has allowed the expected speed of the mainland ice plane after the rupture of ice on the shelf. The Ross Ice Shelf is the largest Antarctic ice shelf (an area of ​​approximately 487,000 square kilometers (188,000 sq. N, mi) and about 800 kilometers (500 miles): the size of France). Wilkins Ice Shelf is another ice shelf that has suffered a major setback. The ice shelf has an area of ​​16,000 km 2 (6,200 sq. N, mi) in 1998 when 1,000 km 2 (390Ã, sqÃ, mi) disappeared that year. In 2007 and 2008, significant rifting developed and led to the loss of an area of ​​1,400 km <2> (540Ã, sqÃ, mi) and some of the calving occurring in the Austral winter. Calves appear to have been produced from preconditioning such as thinning, probably due to basal melting, because the melt surface is not clear, leading to a reduction in pinning pinning connection strength. The thinner ice then experiences a split and separation. This period culminated in the collapse of an ice bridge connecting the main ice shelf to Charcot Island causing an additional loss of 700 km 2 (270Ã, sqÃ, mi) between February and June 2009.
The Dakshin Gangotri glacier, a small glacier in the Antarctic ice sheet, receded on an average of 0.7 m (2.3 ft) annually from 1983 to 2002. On the Antarctic Peninsula, which is the only part of Antarctica that extends well in north of the Antarctic Circle, there are hundreds of retreating glaciers. In one study of 244 glaciers on the peninsula, 212 had retreated on average 600 m (2,000 ft) from where they were first measured in 1953. Pine Island Glacier, Antarctic outflow glacier that flows into the Amundsen Sea. A study from 1998 concluded that glaciers depleted 3.5 m (11 ft) Â ± 0.9 m (3.0 ft) per year and retreated a total of 5 km (3.1 m) in 3.8 years. The Pine Island Glacier terminus is a floating ice sheet, and the point where it begins to float back 1.2 km (0.75 miles) per year from 1992 to 1996. This glacier drains most of the Western Antarctic Ice Sheet.
A study published in 2014 found, a rapid runway line retardation in 1992-2011. Based on a study from 2005, the largest retreat was seen in the Sjogren Glacier, which is now 13 km (8.1 miles) farther inland than it did in 1953. There are 32 glaciers measured that have advanced; However, these glaciers show only a slight face averaging 300 m (980 ft) per glacier, which is significantly smaller than the observed large retreats. Thwaites Glacier, which also shows evidence of depletion, has been referred to as the weak stomach of the Western Antarctic Ice Sheet. A study published in 2014 found a rapid runoff in 1992-2011. Totten's glacier, is a large glacier that dries most of the East Antarctic Ice Sheet. A study in 2008 concluded that Totten's glaciers are currently losing mass. A study published in 2015 concludes that Totten Glacier, has the largest contribution of ice-depleting levels in the continent of East Antarctica, and that depletion is driven by an increase in basal melt, due to ocean processes, and is influenced by polynya activity. In addition, the warm Deep Water Circumpolar, has been observed during summer and winter on the nearest continental shelf below 400 to 500 meters of cool Antarctic Water Surfaces.
The effect of glacier retreat
The decline of glaciers will have a number of different quantitative effects. In an area that relies heavily on water runoff from melting glaciers during warm summer months, the continuation of the current cracks will eventually deplete glacial ice and substantially reduce or eliminate runoff. Reduction of runoff will affect the ability to irrigate crops and will reduce the flow of summer flow needed to keep dams and reservoirs replenished. This situation is particularly acute for irrigation in South America, where many artificial lakes are filled almost exclusively by melting glaciers. Central Asian countries also historically rely on seasonal melting water glaciers for irrigation and drinking supplies. In Norway, the Alps, and Northwest Pacific North America, glacier runoff is important for hydroelectricity.
Some of these retreats have resulted in efforts to slow the disappearance of glaciers in the Alps. To slow the melting of glaciers used by certain Austrian ski resorts, some of Stubai and Pitztal's glaciers are partially covered by plastics. In Switzerland plastic sheeting is also used to reduce the melting of glacial ice that is used as a ski slope. While covering the glaciers with plastic sheeting may prove to be advantageous for small-scale ski resorts, this practice is not expected to be economically practical on a much larger scale.
Many species of freshwater and saltwater plants and animals rely on water fed by glaciers to ensure the cold water habitat they have adapted. Some freshwater fish species need cold water to survive and reproduce, and this is especially true with salmon and ruthless trout. Reduced glacial surface flow can lead to inadequate river flow to allow this species to flourish. Changes in ocean currents, due to increased freshwater inputs from glacier melting, and potential changes in thermohaline circulation in the World Ocean, can affect the existing fisheries in which humans also depend.
One of the main concerns is the increased risk of the Ice Flood Slope (GLOF), which in the past had a major effect on life and property. Ice lelezers left by retreating glaciers are often held up by moraines that can become unstable and are known to collapse if they are violated or replaced by earthquakes, landslides or avalanches. If the moraine terminal is not strong enough to hold the rising water behind it, it can break, leading to a large local flood. The likelihood of such occurrences increases because of the creation and expansion of glacial lakes resulting from glacier cracks. Floods in the past have been deadly and resulted in enormous property damage. The towns and villages in the steep narrow valleys that flow from the glacial lakes are at greatest risk. In 1892 a GLOF released about 200,000 m 3 (260,000 cuÃ, yd) of water from Lake Glacier de TÃÆ'ªte Rousse, resulting in the death of 200 people in the town of Saint-Gervais, France. -les-Bains. GLOF has been known to occur in every region of the world where glaciers are located. Continued glacier cracks are expected to create and extend glacial lakes, increasing the danger of GLOFs in the future.
The potential for major sea level rise is largely dependent on melting of polar ice in Greenland and Antarctica, because this is where most of the glacial ice is located. If all the ice in the polar ice cap melts, the world's oceans will rise about 70 m (230 ft). Although it was previously thought that polar ice did not contribute greatly to sea level rise (IPCC 2007), recent studies have confirmed that Antarctica and Greenland contribute 0.5 millimeters (0.020 a year) each for global sea level rise. The fact that IPCC estimates do not include rapid decay of ice sheets into sea level predictions makes it difficult to ascertain reasonable estimates for sea level rise but recent studies have found that the minimum sea level rise will be about 0.8 meters (2.6 feet ). before 2100.
See also
- Glaciers list
- The effects of global warming
- Extreme Ice Survey
- Post-glacial rebound
References
Further reading
Source of the article : Wikipedia
Source of the article : Wikipedia
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