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Climate feedbacks - the connectivity of the positive ice/snow albedo feedback, terrestrial snow and vegetation feedbacks and the negative cloud/radiation feedback Climate feedbacks - the connectivity of the positive ice/snow albedo feedback, terrestrial snow and vegetation feedbacks and the negative cloud/radiation feedback
Feedback refers to the modification of a process by changes resulting from the process itself. Positive feedbacks accelerate the process, while negative feedbacks slow it down. Part of the uncertainty around future climates relates to important feedbacks between different parts of the climate system: air temperatures, ice and snow albedo (reflection of the sun’s rays), and clouds. An important positive feedback is the ice and snow albedo feedback...
01 Jun 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Radiation from Chernobyl Radiation from Chernobyl
What do the Chernobyl disaster, the Three Gorges dam in China and the spread of the Sahel have in common? In each case natural and manmade influences have forced thousands, sometimes millions of people, to leave their land or country of origin.
29 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Ground deposition of 137Cs after the Chernobyl accident Ground deposition of 137Cs after the Chernobyl accident
The Chernobyl nuclear accident was a devasting catastrophe with effects measurable over a huge distance. This map shows areas that have elevated levels of cesium 137 in Nordic area, in the years after the Chernobyl accident.
13 Feb 2006 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Impact of Temperature Rise on Tea in Kenya Impact of Temperature Rise on Tea in Kenya
Increasing temperatures will likely affect major crops such as tea in Kenya. Major impacts on food production will come from changes in temperature, moisture levels, ultraviolet (UV) radiation, CO2 levels, and pests and diseases. This graphic shows the current locations of tea-growing areas in Kenya, and how some of these areas are expected to become less suitable for tea-growing if there is a temperature rise of 2 degrees Celsius.
17 May 2005 - by Otto Simonett, UNEP/GRID-Arendal
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Cooling factors Cooling factors
The amount of aerosols in the air has direct effect on the amount of solar radiation hitting the Earth's surface. Aerosols may have significant local or regional impact on temperature. Water vapour is a greenhouse gas, but at the same time the upper white surface of clouds reflects solar radiation back into space. Albedo - reflections of solar radiation from surfaces on the Earth - creates difficulties in exact calculations. If e.g. the polar ice...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Sources of greenhouse gases Sources of greenhouse gases
Shows the sources for greenhouse gases, contributing to climate change, and their relative radiative forcing effect (radiative forcing is the change in the balance between radiation coming into the atmosphere and radiation going out)
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Existing radioactive waste disposal and proposal alternatives for storage Existing radioactive waste disposal and proposal alternatives for storage
Radioactive waste presents a unique problem, where it has to be handled with care to prevent radiation exposure for people, wildlife and contamination. Products from nuclear activities can be reprocessed to a certain degree, but a fair bit of the waste needs to be stored or disposed of in a safe manner. Options include storing in deep mountain chambers/caverns, under the sea floor or even sending it out into space.
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Norwegian emissions of SF6 Norwegian emissions of SF6
SF6 is a gas that is used in circuit breakers and other switchgear as an electrical insulator. SF6 is a highly potent greenhouse gas, over 23,900 times more effective at trapping infrared radiation than carbon dioxide.
12 Feb 2006 - by Philippe Rekacewicz, Emmanuelle Bournay, UNEP/GRID-Arendal
3
Radiative forcing - energy balances and the greenhouse effect Radiative forcing - energy balances and the greenhouse effect
Radiative forcing is the change in the balance between radiation coming into the atmosphere and radiation going out. A positive radiative forcing tends on average to warm the surface of the Earth, and negative forcing tends on average to cool the surface. The figure shows estimates of the globally and annually averaged anthropogenic radiative forcing (in Wm-2) due to changes in concentrations of greenhouse gases and aerosols from pre-industrial t...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Greenhouse effect Greenhouse effect
Human activities are causing greenhouse gas levels in the atmosphere to increase. This graphic explains how solar energy is absorbed by the earth's surface, causing the earth to warm and to emit infrared radiation. The greenhouse gases then trap the infrared radiation, thus warming the atmosphere.
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Cooling factors Cooling factors
The amount of aerosols in the air has direct effect on the amount of solar radiation hitting the Earth's surface. Aerosols may have significant local or regional impact on temperature. Water vapour is a greenhouse gas, but at the same time the upper white surface of clouds reflects solar radiation back into space. Albedo - reflections of solar radiation from surfaces on the Earth - creates difficulties in exact calculations. If e.g. the polar ice...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
3
Greenhouse effect Greenhouse effect
Human activities are causing greenhouse gas levels in the atmosphere to increase. This graphic explains how solar energy is absorbed by the earth's surface, causing the earth to warm and to emit infrared radiation. The greenhouse gases then trap the infrared radiation, thus warming the atmosphere.
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
3
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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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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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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Number of extra skin cancer cases related to UV radiation Number of extra skin cancer cases related to UV radiation
The most widely recognised damage occurs to the skin. The direct effects are sun burn, chronic skin damage (photo-aging) and an increased risk of developing various types of skin cancer. Models predict that a 10 per cent decrease in the ozone in the stratosphere could cause an additional 300,000 non-melanoma and 4,500 (more dangerous) melanoma skin cancers worldwide annually.
29 Nov 2007 - by Emmanuelle Bournay, UNEP/GRID-Arendal
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Effects of enhanced UV-B radiations on crops Effects of enhanced UV-B radiations on crops
Experiments on food crops have shown lower yields for several key crops such as rice, soy beans and sorghum. The plants minimize their exposure to UV by limiting the surface area of foliage, which in turn impairs growth. However the observed drop in yield does not seem serious enough for scientists to sound the alarm.
29 Nov 2007 - by Emmanuelle Bournay, UNEP/GRID-Arendal
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The global solar UV Index The global solar UV Index
The Global Solar UV Index (UVI) is a simple measurement of the UV radiation level at the Earth's surface. It has been designed to indicate the potential for adverse health effects and to encourage people to protect themselves. The higher the Index value, the greater the potential for damage to the skin and eye, and the less time it takes for harm to occur.
29 Nov 2007 - by Emmanuelle Bournay, UNEP/GRID-Arendal
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Skin colour map (indigenous people) Skin colour map (indigenous people)
The twin role played by the skin – protection from excessive UV radiation and absorption of enough sunlight to trigger the production of vitamin D – means that people living in the lower latitudes, close to the Equator, with intense UV radiation, have developed darker skin to protect them from the damaging effects of UV radiation. In contrast, those living in the higher latitudes, closer to the Poles, have developed fair skin to maximize vitamin ...
29 Nov 2007 - by Emmanuelle Bournay, UNEP/GRID-Arendal
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Greenhouse effect Greenhouse effect
Human activities are causing greenhouse gas levels in the atmosphere to increase. This graphic explains how solar energy is absorbed by the earth's surface, causing the earth to warm and to emit infrared radiation. The greenhouse gases then trap the infrared radiation, thus warming the atmosphere.
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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