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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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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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Arctic temperature anomaly patterns Arctic temperature anomaly patterns
Natural climate variability is organized into spatial patterns of high and low pressure regions, represented by the Arctic Oscillation (also called the Northern Annular Mode) and North Pacific patterns in the Northern Hemisphere, and the Southern Annular Mode in the Southern Hemisphere. The patterns of surface temperature anomalies when the Arctic Oscillation and Northern Pacific patterns are in their positive extreme are shown in this fi...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Permafrost extent in the Northern Hemisphere Permafrost extent in the Northern Hemisphere
Permafrost zones occupy up to 24 per cent of the exposed land area of the Northern Hemisphere. Permafrost is also common within the vast continental shelves of the Arctic Ocean. This subsea permafrost formed during the last glacial period when global sea levels were more than 100 m lower than at present and the shelves were exposed to very harsh climate conditions. Subsea permafrost is slowly thawing at many locations. Permafrost of various tempe...
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 May 2010 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Example of enhanced water levels produced from river ice, Liard River, Canada Example of enhanced water levels produced from river ice, Liard River, Canada
The lower curve shows the correspondence between river flow and water levels under open-water conditions. The much greater maximum water levels possible under ice-jam conditions are illustrated by the upper curve. The transition in break-up severity from dynamic to thermal break-up effects (see text) is depicted by the gradually shaded area between the two curves. Dots are observed annual maximum water levels during the spring break up. The 1990...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Greenland, showing rates of surface-elevation change between the late 1990s and 2003 Greenland, showing rates of surface-elevation change between the late 1990s and 2003
Mass-balance estimates for Greenland show thickening at high elevations since the early 1990s at rates that increased to about 4 cm per year after 2000, consistent with expectations of increasing snowfall in a warming climate. However, this mass gain is far exceeded by losses associated with large increases in thinning of the ice sheet near the coast. Total loss from the ice sheet more than doubled, from a few tens of billions of tonnes per year ...
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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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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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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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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Average Recurrence Interval for sea-level events of a given height at Sydney, Australia6c_sidney_level Average Recurrence Interval for sea-level events of a given height at Sydney, Australia6c_sidney_level
For the second half of the 20th century (red line), the average recurrence interval for a sea-level height of a given value is less than half the value for the first half of the 20th century (blue line).
01 Jun 2007 - 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.
20 Jul 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Severity of land degradation Severity of land degradation
The highest levels of land degradation is in Europe. Specifically degraded soils are found especially in semi-arid areas (Sub-Saharan Africa, Chile), areas with high population pressure (China, Mexico, India) and regions undergoing deforestation (Indonesia).
29 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Central Asia in peril Central Asia in peril
Communities face appalling health problems. In Karakalpakstan, Uzbekistan, drinking water is saline and polluted, with a high content of metals that causes a range of diseases. Over the past 15 years there has been a thirty-fold increase in chronic bronchitis and in kidney and liver diseases, especially cancer and arthritic diseases have increased sixty-fold. The infant mortality rate is one of the world's highest.
29 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Common but differentiated responsibilities Common but differentiated responsibilities
All countries can claim “climate credits” by their phase out of ozone depleting substances (ODS) under the Montreal Protocol, and some are beginning to document this contribution. Article 5 countries are those listed as developing and do not have the same goals as industrialized nations.
29 Nov 2007 - by Emmanuelle Bournay, UNEP/GRID-Arendal
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Ozone depletion and climate change Ozone depletion and climate change
Ozone depletion and climate change are two distinct problems but as they both modify global cycles, they cannot be totally separated. There are still many uncertainties concerning the relations between the two processes.
29 Nov 2007 - by Emmanuelle Bournay, UNEP/GRID-Arendal
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Contribution of ecosystems to historical radiative forcing and current greenhouse gas emissions Contribution of ecosystems to historical radiative forcing and current greenhouse gas emissions
Radiative forcing caused by changes in atmospheric composition, alteration in land surface reflectance (albedo), and variation in the output of the sun for the year 2000 relative to conditions in 1750.
30 Nov 2007 - by Philippe Rekacewicz, Emmanuelle Bournay, UNEP/GRID-Arendal
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