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Trends in the ice-breaking date in the Tornio river, Finland Trends in the ice-breaking date in the Tornio river, Finland
The icebreaking date for the Tornio River in Finland has been recorded since 1693. With the increased greenhouse effect, impacts on the cryosphere are likely. One impact will be less ice on rivers and lakes. Freeze-up dates will be delayed, and break-up will begin earlier. The period of river-ice could be shortened by up to a month. Many rivers within the temperate regions could become ice-free or develop only intermittent or partial ice coverage...
12 Feb 2006 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Rising water levels in the Spitamen district (Tajikistan) Rising water levels in the Spitamen district (Tajikistan)
Sudden releases of water into the Spitamen district from Kyrgyzstan are regularly endangering the neighboring Tajik arable land downstream and villages along the river. The Tajik communities are convinced upstream Kyrgyz communities are responsible for the flooding. However, local experts suggest that increased water levels in spring the later years may also be due to increased and rapid ice and snow melt down caused by a warmer climate in the hi...
16 Mar 2006 - by Viktor Novikov, UNEP/GRID-Arendal
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Arctic map, political Arctic map, political
The Arctic is extremely diverse in terms of landscapes, varying from pack and drift ice to rugged shores, flat coastal plains, rolling hills and mountains surpassing 6000 metres above sea level (Denali, 6,194 m asl, in sub-arctic and boreal Alaska). The region has rivers and lakes, tundra and the largest forests in the world (the Russian Taiga). This is a simple grayscale political map.
16 Sep 2006 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Projected changes in the Arctic climate, 2090 - with shipping routes Projected changes in the Arctic climate, 2090 - with shipping routes
The averages of the scenarios in the Arctic Climate Impact Assessment (ACIA) are presented in this figure, for the year 2090, with the surface temperatures over land, the size of the polar ice cap, and the outer limits of permafrost. This map features shipping routes in addition - as the sea ice is decreasing, the potential for developing shipping in the Arctic increases.
16 Sep 2006 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Barents Sea - Oil free zones Barents Sea - Oil free zones
Proposal from the World Wildlife Fund for Nature (WWF) for permanent petroleum-free zones in the Barents Sea. Areas covered with ice for parts of the year are also included in the proposed zones. The map has been drawn up by WWF Norway and is based on vulnerability analyses from Det Norske Veritas (April 2005) and mapping of fish resources from the Norwegian Institute of Marine Research (March 2005).
01 Nov 2006 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Fossil fuel resources and oil and gas production in the Arctic Fossil fuel resources and oil and gas production in the Arctic
The Arctic has been opened up for increased exploration of petroleum, gas and mining activities. The Barents Sea, the Mackenzie Valley in Canada and the Alaskan North Slope, are the areas of chief interest at the moment. With increased temperatures and climate change, it is expected that the commercial intrest for more extraction and exploration will increase, as well as shipping of the products. As sea ice decreases, the shipping lanes will beco...
06 Dec 2006 - by Philippe Rekacewicz & Hugo Ahlenius UNEP/GRID-Arendal
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Mass balance reference glaciers in nine mountain ranges Mass balance reference glaciers in nine mountain ranges
Thirty reference glaciers with almost continuous mass balance measurements since 1975 show an average annual mass loss of 0.58 m water equivalent for the past decade (1996–2005), which is more than twice the loss rate of the period 1986–1995 (0.25 m), and more than four times the rate of the period 1976–1985 (0.14 m). The results from these 30 continuous mass balance series correspond well to estimates based on a larger sample of more tha...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Time series of freeze-up and break-up dates from selected Northern Hemisphere lakes and rivers, 1846–1995 Time series of freeze-up and break-up dates from selected Northern Hemisphere lakes and rivers, 1846–1995
Limited by the availability of detailed observations, most historical evaluations of changes in freshwater ice have focused on relatively simple characteristics, such as the timing of autumn freeze up and spring break up, and maximum ice-cover thickness. Based on 27 long-term (about 150-year) records from around the Northern Hemisphere, Magnuson and others (Figure 8.1) discovered that freeze up has been delayed by approximately six days per hundr...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Overview of world glaciers and ice caps Overview of world glaciers and ice caps
By far the largest area of glaciers and ice fields are found in Canada (about 201 000 km2), followed by Alaska (about 75 000 km2) with about 700 km2 in the rest of the USA. Glaciers and ice fields are concentrated in the High Arctic and western cordillera. The total area of glaciers and ice caps, without the ice sheets and surrounding glaciers and ice caps in Greenland and Antarctica, sums up to 540 000 km2.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Mass balance of Maliy Aktru Glacier, Russian Altai Mass balance of Maliy Aktru Glacier, Russian Altai
Measurements on this valley-type glacier in the North Chuyskiy Range show a slightly negative annual mass balance trend culminating in an ice loss of about 4 m water equivalent over the period 1964–2005.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Northern Hemisphere snow-cover extent anomalies 1966-2005 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 extent was 24.9 million km2, which is 0.6 million km2 less than the 37-year average. In the Northern Hemisphere, spring and summer show the strongest decreases in snow-cover extent. Satellite observations of snow-cover extent show a...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Projected temperatures in the 21th century 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. The averages of the runs from each of the 12 models show increases from 2–4ºC, the range of uncertainty in these model projections.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Temperatures over previous centuries from various proxy records Temperatures over previous centuries from various proxy records
Evidence from tree rings and other temperature proxies suggests that during the previous 500 years global temperatures were 1.0ºC cooler than those of the 20th century during a period roughly from 1300 to 1870 – known as the Little Ice Age. While overall temperatures during the Little Ice Age were cooler than now, there was much year-to-year variability and some warm periods. The coldest part of the Little Ice Age, from 1645 to 1715, was also a t...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Antarctica, showing rates of surface-elevation change derived from satellite radar-altimeter measurements 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 periods of observations (horizontal) and the upper and lower estimates of mass balance (vertical). Measurements by satellite techniques based on gravity indicate mass loss at a rate of 138 ± 73 billion tonnes per year during 200...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Trends in permafrost temperatures and active-layer thickness, Northern Tien Shan mountains Trends in permafrost temperatures and active-layer thickness, Northern Tien Shan mountains
Mountain permafrost in Central Asia occupies approximately 3.5 million square kilometers and makes up about 15 per cent of the total permafrost area in the Northern Hemisphere. The climatic variations during the 20th century and especially during the last two decades have impacted current permafrost temperatures. In the Tien Shan Mountains, Qinghai-Tibet Plateau, and western Mongolian sector of the Altai Mountains, observations over the last 30 ...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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The Cryosphere, components and world maps 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 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 Oct 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Albedo of basic thick sea ice surface types 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 largest to the smallest albedo on earth. Melting snow, bare ice and ponded ice lie within this range. There is a general decrease in the albedo of the ice cover during the melt season as the snow-covered ice is replaced by a mix of me...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Change in the age of ice on the Arctic Ocean, comparing September ice ages in 1988, 1990, 2001 and 2005 Change in the age of ice on the Arctic Ocean, comparing September ice ages in 1988, 1990, 2001 and 2005
The age of sea ice in the Arctic is changing, and not only the extent and concentrations. Studies show that in recent years there is a higher proportion of younger ice to older ice than was observed in the late 1980s. This analysis is based on results from a simulation using drifting buoy data and satellite-derived ice-concentration data. The darker the colour, the older the ice.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Melting ice on Mount Kilimanjaro, East Africa 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 and volume are being used as indicators for global warming and climate change.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Ice-albedo feedback process 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 amount of open water. This causes the albedo to further decrease, increasing the rate of heating and further accelerating melting.
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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