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Shrinking of Fedchenko Glacier in the Pamirs of Tajikistan Shrinking of Fedchenko Glacier in the Pamirs of Tajikistan
Significant loss of glaciers in Central Asia began around the 1930s, and become more dramatic in the second half of the 20th century and continue into the 21st century. Glacier area was reduced in the Tien Shan and in the Pamirs, including its largest Fedchenko Glacier. The debris-covered glacier tongue retreated by more than 1 km since 1933 and lowered by about 50 m since 1980.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Glacier shrinking on Cumberland Peninsula, Baffin Island, Canadian Arctic Glacier shrinking on Cumberland Peninsula, Baffin Island, Canadian Arctic
A new glacier inventory based on satellite data shows that the glacier cover reduced by about 22 per cent between the Little Ice Age (LIA) maximum extent and 2000. Changes in glacier area and volume are being used as indicators for climate change and global warming.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Water towers of Asia - glaciers, water and population in the greater Himalayas-Hindu Kush-Tien Shan-Tibet region Water towers of Asia - glaciers, water and population in the greater Himalayas-Hindu Kush-Tien Shan-Tibet region
The Himalayas–Hindu Kush, Kunlun Shan, Pamir and Tien Shan mountain ranges function as water towers, providing water to people through much of Asia. The glacier-fed rivers originating from the Himalaya mountain ranges surrounding the Tibetan Plateau comprise the largest river run-off from any single location in the world. While the mountains are homes to some 170 million people, the rivers that drain these mountains influence the lives of about 4...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Glacier front variations in the European Alps Glacier front variations in the European Alps
Large Alpine glaciers have retreated continuously since the mid- 19th century, whereas steep mid-sized glaciers reacted with readvances in the 1890s, 1920s and between the 1970s and 1980s due to the somewhat cooler and wetter periods. Small glaciers feature a high annual variability with a clear shrinking trend.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Northern Sea Route and the Northwest Passage compared with currently used shipping routes Northern Sea Route and the Northwest Passage compared with currently used shipping routes
Climate models project that summer sea ice in the Arctic Basin will retreat further and further away from most Arctic landmasses, opening new shipping routes and extending the navigation season in the Northern Sea Route by between two and four months. Previously frozen areas in the Arctic may therefore become seasonally or permanently navigable, increasing the prospects for marine transport through the Arctic and providing greater access to Arcti...
01 Oct 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Schematic diagram of glacier, permafrost and forest limits as a function of mean annual air temperature and average annual precipitation Schematic diagram of glacier, permafrost and forest limits as a function of mean annual air temperature and average annual precipitation
Glaciers and ice caps form around the world where snow deposited during the cold/humid season does not entirely melt during warm/dry times. This seasonal snow gradually becomes denser and transforms into perennial firn (rounded, well-bonded snow that is older than one year) and finally, after the air passages connecting the grains are closed off, into ice. The ice from such accumulation areas then flows under the influence of its own weight and t...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Ice sheets, schematic illustration for Greenland and Antarctica Ice sheets, schematic illustration for Greenland and Antarctica
The ice cover in Greenland and Antarctica has two components – thick, grounded, inland ice that rests on a more or less solid bed, and thinner floating ice shelves and glacier tongues. An ice sheet is actually a giant glacier, and like most glaciers it is nourished by the continual accumulation of snow on its surface. As successive layers of snow build up, the layers beneath are gradually compressed into solid ice. Snow input is balanced by glaci...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Projected sea-level rise for the 21st century Projected sea-level rise for the 21st century
The projected range of global averaged sea-level rise from the IPCC 2001 Assessment Report for the period 1990 to 2100 is shown by the lines and shading. The updated AR4 IPCC projections made are shown by the bars plotted at 2095, the dark blue bar is the range of model projections (90% confidence limits) and the light blue bar has the upper range extended to allow for the potential but poorly quantified additional contribution from a dynamic res...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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World ocean thermohaline circulation World ocean thermohaline circulation
The global conveyor belt thermohaline circulation is driven primarily by the formation and sinking of deep water (from around 1500m to the Antarctic bottom water overlying the bottom of the ocean) in the Norwegian Sea. When the strength of the haline forcing increases due to excess precipitation, runoff, or ice melt the conveyor belt will weaken or even shut down. The variability in the strength of the conveyor belt will lead to climate change in...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Monthly average sea ice extent globally and in both hemispheres Monthly average sea ice extent globally and in both hemispheres
In the Arctic, winter sea ice extends over an area of approximately 15 million km2 at its peak in March and up to 7 million km2 in September, at the end of the summer melt season. Corresponding numbers for the Southern Ocean around the Antarctic continent are approximately 3 million km2 in February during the Antarctic summer and 18 million km2 at the height of winter in September. In regions with seasonal sea ice, the ice cover achieves a thickn...
01 Oct 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Mean snow-cover extent in the Northern Hemisphere 1966-2006 Mean snow-cover extent in the Northern Hemisphere 1966-2006
Snow occurs predominantly on the northern continents, on the sea ice of the Arctic Ocean and on Antarctica. On the Northern Hemisphere continents, snow covers a maximum mean area of 45.2 million km2, typically in January. The minimum snow-cover extent usually occurs in August and covers a mean area of 1.9 million km2, most of which is snow on the Greenland ice sheet and on mountain glaciers. As a result, snow cover is the surface characteristic r...
01 Oct 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Shrinking Lewis Glacier, Mount Kenya Shrinking Lewis Glacier, Mount Kenya
The tropical Lewis Glacier retreated by more than 800 m between 1893 and 2004 and lost almost 16 m water equivalent of its thickness between 1979 and 1996. Located on Mount Kenya, this is one of few locations in Africa with glaciers.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Arctic sea ice minimum extent in September 1982 and 2005 Arctic sea ice minimum extent in September 1982 and 2005
The red line indicates the median minimum extent of the ice cover for the period 1979–2000. This figure compares the Arctic sea-ice extent in September for the years 1982 (the record maximum since 1979) and 2005 (the record minimum). The ice extent was 7.5 million km2 in 1982 and only 5.6 million km2 in 2005, a difference of 25 per cent. As has been observed in other recent years, the retreat of the ice cover was particularly pronounced along the...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Ratio of existing ski areas in the Alps with natural snow-reliability under current conditions and warmer conditions Ratio of existing ski areas in the Alps with natural snow-reliability under current conditions and warmer conditions
Winter tourism is a significant part of the economy of Alpine countries and the most important source of income in many regions. In Austria, winter tourism revenue makes up 4.5 per cent of GNP and half of the total income from tourism. Much of winter tourism is based around the ski industry, which is dependent on reliable snow conditions. Although snow fall is expected to increase at high elevations, it is winter temperatures that largely determi...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Overview on glacier changes since the end of the Little Ice Age Overview on glacier changes since the end of the Little Ice Age
Glaciers and ice caps reached their Holocene (the past 10 000 years) maximum extent in most mountain ranges throughout the world towards the end of the Little Ice Age, between the 17th and mid-19th century. Over the past hundred years a trend of dramatic shrinking is apparent over the entire globe, especially at lower elevations and latitudes. Within this general trend, strong glacier retreat is observed in the 1930s and 1940s, followed by static...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Population size of Peary caribou in the Canadian Arctic islands Population size of Peary caribou in the Canadian Arctic islands
In northwestern North America, recent warming has led to a dramatic increase in the number of days of above freezing temperatures during the migration period for the caribou (Rangifier tarandus). Thawing and subsequent re-freezing of snow results in ice layers in the snow pack which hinder travel of Rangifer and make it harder to cater for food. There have been catastrophic declines in the Peary caribou on the Arctic islands of North America and ...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Projected winter temperature changes in the Arctic Projected winter temperature changes in the Arctic
The changes in cold-season mean temperatures over Arctic land regions are broken into three latitudinal bands for each region, as shown on the small map (which has an outer rim of 50° N). Error bars represent standard deviation from the mean. Where greater warming is projected at higher latitudes than at lower latitudes, temperature gradients will be reduced along large north-flowing rivers and this will likely reduce break-up severity. The rever...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Glacier changes on Nevado de Santa Isabel, Colombia Glacier changes on Nevado de Santa Isabel, Colombia
With spectacular mountain peak glaciers melting away, the NEvado de Santa Isabel area in Colombia becomes less attractive to tourists. In addition, the local forestry and agricultural fertility suffer may suffer from reduced spring water. The retreat of glaciers is an indicator for changes in regional and global climate.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Formation of lakes and glacier lake outburst floods (GLOFs) by Medvezhi Glacier, Pamirs Formation of lakes and glacier lake outburst floods (GLOFs) by Medvezhi Glacier, Pamirs
The increasing number of glacial and moraine lakes in Central Asian mountains is a matter of great concern. One of the surging glaciers that poses a potential threat is the 15 km long Medvezhi (Bear) Glacier in the Pamirs mountains of Tajikistan. Its surges have repeatedly caused lake formation, outburst and subsequent floodings. In 1963 and 1973, the surge of the glacier was so significant (1 to 2 km increase in length) that the ice dam exceeded...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Cryosphere - winter seasons, Northern and Southern Hemispheres Cryosphere - winter seasons, Northern and Southern Hemispheres
Seasonal variation in the extent of ice and snow cover is greatest in the Northern Hemisphere. Imagine the Earth with white caps on the top and bottom. The top cap increases by a factor of six from summer to winter, while the bottom cap only doubles from summer to winter. This difference is due to snow cover: in the Northern Hemisphere snow cover on land varies from less than 2 million km2 in the summer to 40 to 50 million km2 in the winter3. The...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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