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Collection: Global Outlook for Ice and Snow

Global Outlook for Ice and SnowGlobal Outlook for Ice and Snow
Global outlook for ice & snow provides an up-to-date, concise review of the state of the environment and the trends in ice and snow-covered regions (cryosphere) of the world. It features case studies, illustrations, graphics and maps and serves as an educational and reference publication. With a broad target audience that includes decision-makers at many levels, the report looks at the significance of changes in the cryosphere to human well-being and the implications for policy.
Available online at: http://www.grida.no/publications/geo-ice-snow/
Antarctica, topographic map Antarctica, topographic map
Antarctic is the fifth largest continent of the world at 14 million square kilometres and is covered by a permanent continental ice sheet. The ice is distributed in two major ice sheets, the East Antarctic and the West Antarctic, and in addition there are shelf ice, extending over the sea water. Antarctic inland ice ranges in thickness up to 5000 m, with an average thickness of about 2400 m, making Antarctica by far the highest of the continents....
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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The Cryosphere, world map The Cryosphere, world map
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 millennia to millions of years, but may also have more rapid effects on, for example, sea level. Snow and sea ice, with their large areas but relatively small volumes, are connected to key interactions and feedbacks at global scales...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Sea ice concentration change over the 21st century as projected by climate models Sea ice concentration change over the 21st century as projected by climate models
The data are taken from climate model experiments of 12 (out of 24) different models that were conducted for the IPCC Assessment Report 4 using the SRES A1B greenhouse gas emission scenario. Plots on the right show changes in late summer and those on the left show changes in late winter. Notes: 1) sea ice extent is the area in which a defined minimum of sea ice can be found. sea ice concentration is the proportion of the ocean area actually cover...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Arctic temperatures in the 20th century, modeled and observed Arctic temperatures in the 20th century, modeled and observed
Observed Arctic winter land temperatures and IPCC model recreations for the 20th century. Note that although these model runs are able to capture the range of Arctic warm and cold periods, the timing of the peaks varies, suggesting that the early 20th century warming was due to random causes, while the increases at the end of the century shown by all the models supports CO2 as an external forcing of the Arctic climate system.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Projected increase (days) of the navigation season through the Northern Sea Route as an average of 5 ACIA model projections Projected increase (days) of the navigation season through the Northern Sea Route as an average of 5 ACIA model projections
The Northern Sea Route (NSR) is a seasonally ice-covered marine shipping lane along the Russian coasts, from Novaya Zemlya in the west to the Bering Strait in the east. The NSR is administered by the Russian Ministry of Transport and has been open to marine traffic of all nations since 1991. For trans-Arctic voyages, the NSR represents a saving in distance of up to 40 per cent from Northern Europe to northeastern Asia and northwestern North Ameri...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Variations in snow depth and ice cover, alpine lake at Hardangervidda plateau, Norway Variations in snow depth and ice cover, alpine lake at Hardangervidda plateau, Norway
Climate warming means that lowland lakes typically are experiencing longer ice-free periods, promoting greater biological productivity. However, despite this warming trend, biological productivity may be reduced, at least temporarily, in alpine areas with increased winter precipitation. During years with high winter precipitation in alpine areas of western Norway, in spite of higher temperatures, fish growth and recruitment were lower than in low...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Arctic sea ice minimum extent in September 1982 and 2008 Arctic sea ice minimum extent in September 1982 and 2008
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 2008. The ice extent was 7.5 million km2 in 1982 and only 5.6 million km2 in 2005 and down to 4.3 million km2 in 2007. As has been observed in other recent years, the retreat of the ice cover was particularly pronounced along the Eurasian coas...
18 Apr 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Ice avalanches of the Nevados Huascarán in Peru Ice avalanches of the Nevados Huascarán in Peru
Many disasters have been recorded from the glaciers in the Cordillera Blanca. The 1962 and 1970 events originating from Glaciar 511 on the Nevados Huascarán, the highest peak of which is at 6768 m above sea level in the Peruvian Andes, were particularly severe. On 10 January 1962, an ice avalanche took place with an estimated starting volume of 10 million m3; the avalanche travelled down 16 km and destroyed the city of Ranrahirca, where 4000 peop...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Increases in annual temperatures for a recent five-year period, relative to 1951-1980 Increases in annual temperatures for a recent five-year period, relative to 1951-1980
Warming is widespread, generally greater over land than over oceans, and the largest gains in temperatures for the planet are over the North American Arctic, north central Siberia, and on the Antarctic Peninsula. These recent increases in temperature are confirmed by changes in other features: loss of sea ice, shift of tundra to shrub vegetation, and migration of marine and terrestrial ecosystems to higher latitudes.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Trends in Arctic sea-ice extent in March (maximum) and September (minimum) in the time period of 1979–2006 Trends in Arctic sea-ice extent in March (maximum) and September (minimum) in the time period of 1979–2006
For the Northern Hemisphere (primarily the Arctic), observations using remote sensing technologies have been used to measure the extent and the to assess the development. Despite considerable year-to-year variability, significant negative trends are apparent in both maximum and minimum ice extents, with a rate of decrease of 2.5 per cent per decade for March and 8.9 per cent per decade for September (linear least squares reqression). The differen...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Mountain permafrost patterns and temperature gradients Mountain permafrost patterns and temperature gradients
Steep terrain and strong variability in surface temperatures are typical of mountain permafrost. The cross section in the foreground shows the complex distribution of subsurface temperatures characteristic of mountains, with the isotherms (lines linking points of equal temperature) nearly vertical in the ridge of the mountain. In the background, the colours on the mountain surface illustrate the strong variability in ground temperatures caused by...
01 Jun 2007 - by Stephan Gruber, University of Zürich. Hugo Ahlenius, UNEP/GRID-Arednal
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Arctic delta pond ecosystems, seasonal flooding and adaptation Arctic delta pond ecosystems, seasonal flooding and adaptation
The physical development and ecosystem health of river deltas in cold regions are strongly controlled by ice processes and thus are highly susceptible to the effects of climate change. As an example, the photograph shows a typical lake/pond and river network in the Peace-Athabasca Delta (Canada), one of the largest freshwater deltas in the world. The water budget and sediment-nutrient supply for the multitude of lakes and ponds that dot the ripar...
01 Nov 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Trends in snow-covered area for the Northern Hemisphere 1922-2005 Trends in snow-covered area for the Northern Hemisphere 1922-2005
Observations of snow-covered area for the Northern Hemisphere show a significant development in the later 20th century, with a reduction of the area covered by snow in the spring (March-April) from some 38 million km2 in the 1930-ies to todays 35 million km2. Snow represents an important resource for water, ecosystems and human activities, as well as for reflecting incoming sun light. The linear trend shows a decrease in snow-covered area of 2.7 ...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Glaciers monitored through the World Glacier Monitoring Service Glaciers monitored through the World Glacier Monitoring Service
Worldwide collection of information about ongoing glacier changes was initiated in 1894 with the foundation of the International Glacier Commission at the 6th International Geological Congress in Zurich, Switzerland. Today, the World Glacier Monitoring Service continues to collect and publish standardized information on ongoing glacier changes. WGMS is a service of the Commission for the Cryospheric Sciences of the International Union of Geodesy ...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Monthly average sea ice extent globally and in both hemispheres (radial) Monthly average sea ice extent globally and in both hemispheres (radial)
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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Projected changes in permafrost (Northern Hemisphere) Projected changes in permafrost (Northern Hemisphere)
Modelled permafrost temperatures (mean annual temperature at the permafrost surface) for the Northern Hemisphere (Arctic), derived by applying climate conditions to a spatially distributed permafrost model. (a) Present-day: temperatures averaged over the years 1980– 1999. Present-day climatic conditions were based on the CRU2 data set with 0.5° x 0.5° latitude/longitude resolution. (b) Future: projected changes in temperatures in comparison with ...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Trends in spring temperatures and ice break-up dates in Canada Trends in spring temperatures and ice break-up dates in Canada
In Canada, recent evidence indicates a shortening of the freshwater-ice season over much of the country with the reduction being mainly attributable to earlier break ups. These trends match those in surface air temperature during the last 50 years. For example, similar spatial and temporal patterns have been found between trends (1966 to 1995) in autumn and spring 0°C isotherms (lines on a map showing location of 0°C air temperatures) and lake fr...
01 Oct 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Regional changes in Arctic and Antarctic sea ice Regional changes in Arctic and Antarctic sea ice
There are major regional differences for the Arctic sea ice, with the strongest decline in ice extent observed for the Greenland Sea (10.6 per cent per decade). The smallest decreases of annual mean sea ice extent were found in the Arctic Ocean, the Canadian Archipelago and the Gulf of St. Lawrence. In the marginal Arctic seas off Siberia (the Kara, Laptev, East Siberian and Chukchi Seas) a slight negative, but not significant, trend in ice exten...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Trends in permafrost temperatures during the last 23 to 28 years in northern Alaska Trends in permafrost temperatures during the last 23 to 28 years in northern Alaska
There has been a general increase in permafrost temperatures during the last several decades in Alaska, northwest Canada, Siberia, and northern Europe. Permafrost temperature records have been obtained uninterrupted for more than 20 years along the International Geosphere-Biosphere Programme Alaskan transect, which spans the entire continuous permafrost zone in the Alaskan Arctic. Records from all locations along the transect show a substantial w...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Caucasus ice-rock avalanche in Russian Republic of North Ossetia Caucasus ice-rock avalanche in Russian Republic of North Ossetia
An ice-rock avalanche in the Kazbek region sheared off almost the entire Kolka Glacier and devastated the Genaldon valley. The satellite images show the region before (July 22, 2001) and after (October 6, 2002) the ice-rock avalanche of September 20, 2002.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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