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Distribution of coldwater and tropical coral reefs Distribution of coldwater and tropical coral reefs
Coral reefs are marine ridges or mounds, which have formed over millennia as a result of the deposition of calcium carbonate by living organisms, predominantly corals, but also a rich diversity of other organisms such as coralline algae and shellfish. The coldwater reefs are highly susceptible to deep-sea trawling and ocean acidification from climate change, which has its greatest impacts at high latitudes, while tropical reefs will become severe...
01 Feb 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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canyondsw canyondsw
About canyondsw
29 Nov 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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stocks stocks
About stocks
29 Nov 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Trends in natural disasters Trends in natural disasters
With growing population and infrastructures the world’s exposure to natural hazards is inevitably increasing. This is particularly true as the strongest population growth is located in coastal areas (with greater exposure to floods, cyclones and tidal waves). To make matters worse any land remaining available for urban growth is generally risk-prone, for instance flood plains or steep slopes subject to landslides. The statistics in this graphic r...
29 Nov 2007 - by Emmanuelle Bournay, UNEP/GRID-Arendal
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Climate change and tropical coral reefs, scenarios for bleaching events Climate change and tropical coral reefs, scenarios for bleaching events
Projected areas of above normal sea temperature where coral bleaching is likely to occur for the SRES A2 scenario (continuing current trends) by two different models, the PCM (1.7°C increase in 100 years) and the HadCM3 (3°C increase in 100 years) by approximately 2035 (left) and by 2055 (right). Both models project severe annual bleaching in more than 80% of the Worlds coral reefs by 2080.
01 Feb 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Acidification due to climate change - impacts for oceans and coral reefs Acidification due to climate change - impacts for oceans and coral reefs
As carbon concentrations in the atmosphere increase from land use changes and emissions from fossil fuels - so do concentrations in the ocean, with resultant acidification as a natural chemical process. The skeletons of coldwater coral reefs may dissolve, perhaps already within a few decades. The impacts will be greatest at high latitudes. This will have an impact on all marine organisms with calcerous shells and body parts, in addition to coral ...
01 Feb 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Atmospheric concentrations of carbon dioxide (CO2) - Mauna Loa or Keeling curve Atmospheric concentrations of carbon dioxide (CO2) - Mauna Loa or Keeling curve
Atmospheric concentration of CO2 is steadily rising, and oceans directly assimilate CO2. As ocean concentration of CO2 increases, the oceans automatically become more acidic. This, in turn, may have severe impacts on coral reefs and other biocalcifying organisms. There is little debate on the effect as this is a straight-forward chemical process, but the implications for marine life, that may be severe due to many very pH-sensitive relationships...
01 Nov 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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shelfwater shelfwater
About shelfwater
29 Nov 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Major pathways and origins of invasive species infestations in the marine environment Major pathways and origins of invasive species infestations in the marine environment
All across the planet, the number and severity of outbreaks and infestations of invasive species (i.e. species purposefully or accidentally introduced in non-native environments) is growing, and invasions of marine habitats are now occurring at an alarming rate. Exotic and invasive species have been identified by scientists and policymakers as a major threat to marine ecosystems, with dramatic effects on biodiversity, biological productivity, hab...
01 Feb 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Primary threats to the marine environment Primary threats to the marine environment
Each of the big five stressors (not in order of magnitude), 1) Climate change; 2) Pollution (mainly coastal), 3) Fragmentation and habitat loss (from e.g. dredging/trawling, use of explosives in fishing on coral reefs etc.), 4) Invasive species infestations, and 5) Over-harvest from fisheries may individually or combined result in severe impacts on the biological production of the worlds oceans and the services they provide to billions of people ...
01 Nov 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Tropical sea temperature rises and coral reefs - climate change scenarios Tropical sea temperature rises and coral reefs - climate change scenarios
The impacts of coral reefs from rising sea temperatures. When coral reefs become heat-exposed they die, leaving the white dead coral, also known as bleaching. With even moderate pollution, the coral are easily overgrown with algae, or broken down by wave activity or storms, leaving only “coral rubble” on the ocean bed.
01 Feb 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Invasive species in the marine environment - problem regions Invasive species in the marine environment - problem regions
The locations of major problem areas for invasive species infestations or occurrence of exotic species in the marine environment. The impacted areas are concurrent with the areas subjected to the worst pollution, the most intensive fisheries and bottom trawling, and major shipping routes. The areas in the figure have been highlighted based on an overview of literature, and the delineation of the areas are approximate.
01 Feb 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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scenarios scenarios
About scenarios
29 Nov 2007 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Tropical cyclone frequency Tropical cyclone frequency
Tropical cyclones, or hurricanes or typhoons, are storm weather systems, characterised by a low pressure centre, thunderstorms and high windspeeds. As the name testifies, these occur in the areas between the tropics, in the tropical areas. Cyclones can, after they have formed in the oceans, move in over populated areas, creating much damage and even natural disasters.
09 Oct 2007 - by Emmanuelle Bournay, UNEP/GRID-Arendal
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Trends in fisheries and aquaculture production (2000-2005) Trends in fisheries and aquaculture production (2000-2005)
The world's marine fisheries have stagnated or slightly declined in the last decade, offset only by increases in aquaculture production. A major reason why the decline has not become more evident is likely because of advances in fishing efficiency, shift to previously discarded or avoided fish, and the fact that the fishing fleet is increasingly fishing in deeper waters
01 Feb 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
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Regulation of the Tigris and Euphrates rivers Regulation of the Tigris and Euphrates rivers
Water has long been associated with conflicts between neighbouring countries. This graphic shows how water from the Tigris and Euphrates rivers is used in Iraq, and that neighbouring Syria and Turkey influence the flow of this water. The graphic shows the locations of main dams, swamps and horticulture in the region. It also shows five of the major ways in which land is used in the region: forest and grazing land; rain-fed agriculture (grains, ve...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Global International Waters Assessment (GIWA) case studies Global International Waters Assessment (GIWA) case studies
The Global International Waters Assessment (GIWA) is an example of a comprehensive strategic assessment designed to identify priorities for remedial and mitigatory actions in international waters. This graphic shows GIWA case studies for the Black Sea, the Amazon, the Great Barrier Reef and the Agulhas Current. Each case study includes an introduction and maps of the region and a discussion of the issues of concern for that region, such as freshw...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Trends in continental river discharge Trends in continental river discharge
River flow is cyclical in nature, with alternating cycles of wet and dry years. This graphic uses bar graphs to show the average annual volumes of river runoff in cubic kilometres for each continent from 1921 to 1985. Over the time period the discharge there has been no obvious trends, but a certain degree of fluctation, the level dependent on the area of the basins and the precipitation over the area. The sizes of the bars in this graph reflect ...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Global International Waters Assessment Tools Global International Waters Assessment Tools
Global International Waters Assessment's (GIWA) assessment tools for monitoring the world's water resources, incorporating five major environmental concerns and application of the DPSIR framework (driving forces-pressure-state-impact-response), are now beginning to yield results of practical use for management decisions. This graphic explains the GIWA Assessment Methodology and GIWA's five main environmental concerns, which are: freshwater shorta...
17 May 2005 - by UNEP/GRID-Arendal
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Coastal population and altered coastal zones Coastal population and altered coastal zones
Coastal areas with high population densities are those with the most shoreline degradation or alteration. Densely populated areas close to seas are also the most attractive for a lot of economic activity. The graphic shows the proportion of the population that lives within 100 km of the coast, for each of the world's nations and where there are coastal zones with high degree of human alteration (compared to 'natural' landcover). In addition, the ...
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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