Tag: Snow

Northern Hemisphere snow-cover extent anomalies 1966-2005
Data from satellite monitoring from 1966 to 2005 show that mean monthly snow-cover extent in the Northern Hemisphere is decreasing at a rate of 1.3 per cent per decade. For the calendar year of 2006 average snow-cover ex...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
Projected temperatures in the 21th century
Projected Arctic annual land temperature increases for the first half of the 21st century relative to the average temperature for 1980–99. The average of the IPCC models (the blue line) shows an increase of 3ºC by 2050. ...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
Antarctica, showing rates of surface-elevation change derived from satellite radar-altimeter measurements
The figure shows rates at which the ice-sheet mass was estimated to be changing based on radar-altimeter data (black), mass-budget calculations (red), and satellite gravity measurements (blue). Rectangles depict the time...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
The Cryosphere, components and world maps
Snow and the various forms of ice - the cryosphere - play different roles within the climate system. The two continental ice sheets of Antarctica and Greenland actively influence the global climate over time scales of mi...
01 Oct 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
Albedo of basic thick sea ice surface types
The albedo for different surface conditions on the sea ice range widely, from roughly 85 per cent of radiation reflected for snow-covered ice to 7 per cent for open water. These two surfaces cover the range from the larg...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
Melting ice on Mount Kilimanjaro, East Africa
Close to 50 per cent of the glaciers in Africa, on the Rwenzori Mountains, Mount Kenya and Kilimanjaro have disappeared, while larger glaciers – particularly on Kilimanjaro – have been fragmented. Changes in glacier area...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
Projected reduction in snow 2080-2100
Using one specific climate change model (ECHAM5) and the SRES A2 emission scenario (run 2) the projected loss of snow amounts to decreases of 60–80 per cent in monthly maximum snow water equivalent over most middle latit...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
Ice-albedo feedback process
In spring, the ice is snow-covered and there is very little open water. Most sunlight is reflected, but some is absorbed. This absorbed sunlight leads to melting, which in turn reduces the ice albedo and increases the am...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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 th...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
Trends in spring snow cover duration for the Northern Hemisphere, 1970-2004
Examination of regional trends in spring snow-cover duration from 1969–2003 using NOAA snow-cover data shows the western United States to be among the regions with the strongest decreases. This supports results from stud...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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 su...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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 w...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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 (...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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 gl...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
Annual snowfall pattern for a typical mountain environment, Columbine Pass, Colorado 1971-2000
Mountain snow cover typically develops in the autumn and grows to a maximum depth in early spring. As day length and sun angles increase, so do air temperatures, causing snow cover to warm and begin to melt. Snow cover ...
01 Oct 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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...
01 Oct 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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 w...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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 incom...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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 r...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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