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= = Tropical glaciers = =
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Tropical glaciers are located between the Tropic of Cancer and the Tropic of Capricorn , in the region that lies 23 ° 26 ′ 22 ″ north or south of the equator . Strictly , a tropical glacier is located within the astronomical tropics ; the area where the annual temperature variation is less than the daily variation , a... |
Tropical glaciers are the most uncommon of all glaciers for a variety of reasons . Firstly , the regions are the warmest part of the planet . Secondly , the seasonal change is minimal with temperatures warm year round , resulting in a lack of a colder winter season in which snow and ice can accumulate . Thirdly , few ... |
Near the Equator , ice is still found in East Africa , the Andes of South America and New Guinea . The retreat of equatorial glaciers has been documented via maps and photographs covering the period from the late 1800s to nearly the present . 99 @.@ 64 % of tropical glaciers are in Andean mountains of South America , ... |
= = = Africa = = =
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Almost the entirety of Africa is located within tropical and subtropical climate zones . Its glaciers are found only in two isolated 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 summit of Kilimanjaro has app... |
The Furtwängler Glacier is located near the summit of Kilimanjaro . Between 1976 and 2000 , the area of Furtwängler Glacier was cut almost in half , from 113 @,@ 000 m2 ( 1 @,@ 220 @,@ 000 sq ft ) to 60 @,@ 000 m2 ( 650 @,@ 000 sq ft ) . During fieldwork conducted early in 2006 , scientists discovered a large hole nea... |
To the north of Kilimanjaro lies Mount Kenya , which at 5 @,@ 199 m ( 17 @,@ 057 ft ) is the second tallest mountain on the continent . Mount Kenya has a number of small glaciers that have lost at least 45 % of their mass since the middle of the 20th century . According to research compiled by the U.S. Geological Surv... |
= = = South America = = =
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A study by glaciologists of two small glaciers in South America reveals another retreat . More than 80 % of all glacial ice in the northern Andes is concentrated on the highest peaks in small plains of approximately 1 km2 ( 0 @.@ 39 sq mi ) in size . A 1992 to 1998 observation of the Chacaltaya Glacier in Bolivia and ... |
Research in the region has been less extensive but indicates an overall recline of 7 % between 1977 and 1983 . The Quelccaya Ice Cap is the largest tropical icecap in the world , and all of the outlet glaciers from the icecap are retreating . In the case of Qori Kalis Glacier , which is one of Quelccayas ' outlet glac... |
= = = Oceania = = =
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Jan Carstensz 's 1623 report of glaciers covering the equatorial mountains of New Guinea was originally met with ridicule , but in the early 20th century at least five subranges of the Maoke Mountains ( meaning " Snowy Mountains " ) were indeed still found to be covered with large ice caps . Due to the location of the... |
In 1913 , 4 @,@ 550 m ( 14 @,@ 930 ft ) high Prins Hendrik peaks ( now Puncak Yamin ) was named and reported to have " eternal " snow , but this observation was never repeated . The ice cap of 4 @,@ 720 m ( 15 @,@ 490 ft ) Wilhelmina Peaks , which reached below 4 @,@ 400 m ( 14 @,@ 400 ft ) in 1909 , vanished between ... |
For this mountain there is photographic evidence of massive glacial retreat since the region was first extensively explored by airplane in 1936 in preparation for the peak 's first ascent ( see e.g. [ 1 ] ) . Between then and 2010 , the mountain lost 80 percent of its ice — two @-@ thirds of which since another scient... |
= = Polar regions = =
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Despite their proximity and importance to human populations , the mountain and valley glaciers of tropical and mid @-@ latitude glaciers amount to only a small fraction of glacial ice on the Earth . About 99 percent of all freshwater ice is in the great ice sheets of polar and subpolar Antarctica and Greenland . These... |
= = = Iceland = = =
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The northern Atlantic island nation of Iceland is home to Vatnajökull , which is the largest ice cap in Europe . The Breiðamerkurjökull glacier is one of Vatnajökull 's outlet glaciers , and receded by as much as 2 km ( 1 @.@ 2 mi ) between 1973 and 2004 . In the early 20th century , Breiðamerkurjökull extended to wit... |
Most of the Icelandic glaciers retreated rapidly during the warm decades from 1930 to 1960 , slowing down as the climate cooled during the following decade , and started to advance after 1970 . The rate of advance peaked in the 1980s , after which it slowed down until about 1990 . As a consequence of rapid warming of ... |
= = = Canada = = =
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The Canadian Arctic islands contain the largest area and volume of land ice on Earth outside of the Greenland and Antarctic Ice Sheets and is home to a number of substantial ice caps , including Penny and Barnes ice caps on Baffin Island , Bylot Ice Cap on Bylot Island , and Devon Ice Cap on Devon Island . Glaciers in... |
Other studies show that between 1960 and 1999 , the Devon Ice Cap lost 67 km3 ( 16 cu mi ) of ice , mainly through thinning . All major outlet glaciers along the eastern Devon Ice Cap margin have retreated from 1 km ( 0 @.@ 62 mi ) to 3 km ( 1 @.@ 9 mi ) since 1960 . On the Hazen Plateau of Ellesmere Island , the Simm... |
= = = Northern Europe = = =
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Arctic islands north of Norway , Finland and Russia have all shown evidence of glacier retreat . In the Svalbard archipelago , the island of Spitsbergen has numerous glaciers . Research indicates that Hansbreen ( Hans Glacier ) on Spitsbergen retreated 1 @.@ 4 km ( 0 @.@ 87 mi ) from 1936 to 1982 and another 400 m ( 1... |
= = = Greenland = = =
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In Greenland , glacier retreat has been observed in outlet glaciers , resulting in an increase of the ice flow rate and destabilization of the mass balance of the ice sheet that is their source . The net loss in volume and hence sea level contribution of the Greenland Ice Sheet ( GIS ) has doubled in recent years from... |
Jakobshavn Isbræ in west Greenland , a major outlet glacier of the Greenland Ice Sheet , has been the fastest moving glacier in the world over the past half century . It had been moving continuously at speeds of over 24 m ( 79 ft ) per day with a stable terminus since at least 1950 . In 2002 the 12 km ( 7 @.@ 5 mi ) l... |
The rapid thinning , acceleration and retreat of Helheim , Jakobshavns and Kangerdlugssuaq glaciers in Greenland , all in close association with one another , suggests a common triggering mechanism , such as enhanced surface melting due to regional climate warming or a change in forces at the glacier front . The enhan... |
= = = Antarctica = = =
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Antarctica is intensly cold and arid . Most of the world 's freshwater ice is contained within its sheets . Its most dramatic example of glacier retreat is the loss of large sections of the Larsen Ice Shelf on the Antarctic Peninsula . The recent collapse of Wordie Ice Shelf , Prince Gustav Ice Shelf , Mueller Ice She... |
The Antarctic sheet is the largest known single mass of ice . It covers almost 14 million km2 and some 30 million km3 of ice . Around 90 % of the fresh water on the planet 's surface is held in this area and if melted would raise sea levels by 58 metres . The continent @-@ wide average surface temperature trend of Ant... |
The Antarctic sheet is divided by the Transantarctic Mountains into two unequal sections known as the East Antarctic ice sheet ( EAIS ) and the smaller West Antarctic Ice Sheet ( WAIS ) . The EAIS rests on a major land mass but the bed of the WAIS is , in places , more than 2 @,@ 500 metres below sea level . It would ... |
Ice shelves are not stable when surface melting occurs , and the collapse of Larsen Ice Shelf has been caused by warmer melt season temperatures that have led to surface melting and the formation of shallow ponds of water on the ice shelf . The Larsen Ice Shelf lost 2 @,@ 500 km2 ( 970 sq mi ) of its area from 1995 to... |
Dakshin Gangotri Glacier , a small outlet glacier of the Antarctic ice sheet , receded at an average rate of 0 @.@ 7 m ( 2 @.@ 3 ft ) per year from 1983 to 2002 . On the Antarctic Peninsula , which is the only section of Antarctica that extends well north of the Antarctic Circle , there are hundreds of retreating glac... |
A study published in 2014 found , rapid grounding line retreat in the years 1992 @-@ 2011 . Based on a study from 2005 , the greatest retreat was seen in Sjogren Glacier , which is now 13 km ( 8 @.@ 1 mi ) further inland than where it was in 1953 . There are 32 glaciers that were measured to have advanced ; however , ... |
= = Effects of glacier retreat = =
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The continued retreat of glaciers will have a number of different quantitative effects . In areas that are heavily dependent on water runoff from glaciers that melt during the warmer summer months , a continuation of the current retreat will eventually deplete the glacial ice and substantially reduce or eliminate runo... |
Some of this retreat has resulted in efforts to slow down the loss of glaciers in the Alps . To retard melting of the glaciers used by certain Austrian ski resorts , portions of the Stubai and Pitztal Glaciers were partially covered with plastic . In Switzerland plastic sheeting is also used to reduce the melt of glac... |
Many species of freshwater and saltwater plants and animals are dependent on glacier @-@ fed waters to ensure the cold water habitat to which they have adapted . Some species of freshwater fish need cold water to survive and to reproduce , and this is especially true with salmon and cutthroat trout . Reduced glacial r... |
One major concern is the increased risk of Glacial Lake Outburst Floods ( GLOF ) , which have in the past had great effect on lives and property . Glacier meltwater left behind by the retreating glacier is often held back by moraines that can be unstable and have been known to collapse if breached or displaced by eart... |
The potential for major sea level rise depends mostly on a significant melting of the polar ice caps of Greenland and Antarctica , as this is where the vast majority of glacial ice is located . If all the ice on the polar ice caps were to melt away , the oceans of the world would rise an estimated 70 m ( 230 ft ) . Al... |
= Livermorium =
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Livermorium is a synthetic superheavy element with symbol Lv and atomic number 116 . It is an extremely radioactive element that has only been created in the laboratory and has not been observed in nature . The element is named after the Lawrence Livermore National Laboratory in the United States , which collaborated ... |
In the periodic table , it is a p @-@ block transactinide element . It is a member of the 7th period and is placed in group 16 as the heaviest chalcogen , although it has not been confirmed to behave as the heavier homologue to the chalcogen polonium . Livermorium is calculated to have some similar properties to its l... |
= = History = =
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= = = Unsuccessful synthesis attempts = = =
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In late 1998 , Polish physicist Robert Smolańczuk published calculations on the fusion of atomic nuclei towards the synthesis of superheavy atoms , including ununoctium and livermorium . His calculations suggested that it might be possible to make these two elements by fusing lead with krypton under carefully controll... |
In 1999 , researchers at Lawrence Berkeley National Laboratory made use of these predictions and announced the discovery of livermorium and ununoctium , in a paper published in Physical Review Letters , and very soon after the results were reported in Science . The researchers reported to have performed the reaction
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86
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36Kr + 208
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82Pb → 293
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118Uuo + n → 289
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116Lv + α
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The following year , they published a retraction after researchers at other laboratories were unable to duplicate the results and the Berkeley lab itself was unable to duplicate them as well . In June 2002 , the director of the lab announced that the original claim of the discovery of these two elements had been based... |
= = = Discovery = = =
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Livermorium was first synthesized on July 19 , 2000 , when scientists at Dubna ( JINR ) bombarded a curium @-@ 248 target with accelerated calcium @-@ 48 ions . A single atom was detected , decaying by alpha emission with decay energy 10 @.@ 54 MeV to an isotope of flerovium . The results were published in December 20... |
248
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96Cm + 48
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20Ca → 296
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116Lv * → 293
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116Lv + 3 1
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0n → 289
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114Fl + α
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The daughter flerovium isotope had properties matching those of a flerovium isotope first synthesized in June 1999 , which was originally assigned to 288Fl , implying an assignment of the parent livermorium isotope to 292Lv . Later work in December 2002 indicated that the synthesized flerovium isotope was actually 289... |
= = = Road to confirmation = = =
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Two further atoms were reported by the institute during their second experiment during April – May 2001 . In the same experiment they also detected a decay chain which corresponded to the first observed decay of flerovium in December 1998 , which had been assigned to 289Fl . No flerovium isotope with the same properti... |
The team repeated the experiment in April – May 2005 and detected 8 atoms of livermorium . The measured decay data confirmed the assignment of the first @-@ discovered isotope as 293Lv . In this run , the team also observed the isotope 292Lv for the first time . In further experiments from 2004 to 2006 , the team repl... |
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