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impact of sea level high.ppt

  1. IUBAT- International University Of Business Agriculture And Technology Submitted By sumiya kuntula shithy I’d no: 20109055 sec:A IMPACTS OF SEA LEVEL RISE
  2. The Greenhouse Effect  Infrared (IR) active gases, principally water vapor (H2O), carbon dioxide (CO2) and ozone (O3), naturally present in the Earth’s atmosphere, absorb thermal IR radiation emitted by the Earth’s surface and atmosphere.  The atmosphere is warmed by this mechanism and, in turn, emits IR radiation, with a significant portion of this energy acting to warm the surface and the lower atmosphere.  As a consequence the average surface air temperature of the Earth is about 30° C higher than it would be without atmospheric absorption and re-radiation of IR energy.  This phenomenon is popularly known as the greenhouse effect, and the IR active gases responsible for the effect are likewise referred to as greenhouse gases.
  3. Incoming Solar Radiation 343 W/m2 Reflected Solar Radiation 103 W/m2 Long-wave Radiation 240 W/m 2 CO2 CH4, N2O, O3, Water vapour, aerosols, clouds Earth’s ground temperature, approx 13o C with greenhouse effect, approx - 20o C without it. Doubling CO2 increases temperature by between 1.5o C and 4o C. The Greenhouse Effect “Blanket” of Greenhouse Gases
  4. Greenhouse Effect Greenhouse Effect Sun
  5. The Greenhouse Effect The rapid increase in concentrations of greenhouse gases since the industrial period began has given rise to concern over potential resultant climate changes
  6. Greenhouse Gases and Global Climate Change  The principal greenhouse gas concentrations that have increased over the industrial period are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and chlorofluorocarbons (CFCs).  The observed increase of CO2 in the atmosphere from about 280 ppm in the pre-industrial era to about 364 ppm in 1997 has come largely from fossil fuel combustion and cement production.  Of the several anthropogenic greenhouse gases, CO2 is the most important agent of potential future climate warming because of its large current greenhouse forcing, its substantial projected future forcing, and its long persistence in the atmosphere.
  7. -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1880 1900 1920 1940 1960 1980 2000 Year D Mean Temperature (°C) Recorded Worldwide Temperatures
  8. -3 -2.5 -1.5 -1 -.5 -.1 .1 .5 1 1.5 2.5 3.4 2005 Temperature Changes Compared to 1951-1980
  9. Ozone Layer Depletion and Climate Change  The ozone layer absorbs harmful ultraviolet-B radiation from the sun. Over the past 30 years ozone levels over parts of Antarctica have dropped by almost 40% during some months and a 'hole' in ozone concentrations is clearly visible in satellite observations.  Ozone is been damaged mainly by: 1. Chlorofluorocarbons (CFCs) that are used in refrigerators, aerosols, and as cleaners in many industries. 2. Halons that are used in fire extinguishers. 3. Aircraft emissions of nitrogen oxides and water vapour.  As Ozone is considered to be a greenhouse gas, a depleted ozone layer may partially dampen the greenhouse effect. This may therefore lead to increased global warming.  Conversely, efforts to tackle ozone depletion may result in increased global warming!
  10. The Melting Snows of Mt Kilimanjaro
  11. RELATIVE SEA LEVEL CHANGE  Sea level varies as a result of processes operating on a great range of time-scales, from seconds to millions of years, so that current sea level change is also related to past climate change.  The local change in sea level at any coastal location as measured by a tide gauge depends on the sum of global, regional and local factors and is termed relative sea-level change.  It is so called because it can come about either by movement of the land on which the tide gauge is situated or by the change in the height of the adjacent sea surface.  Relative sea levels are also measured by dating buried coastal vegetation (salt marshes, mangroves, etc.).  Most of the tide gauges are located in mid-latitude northern hemisphere, few in middle of oceans, and contaminated by earth movements.  The main source for the uncertainties in using tide gauge records still remain: poor historical distribution of tide gauges, lack of data from Africa and Antarctica, the GIA corrections used, and localized tectonic activity.
  12. CLIMATE CHANGE AND SEA LEVEL RISE  Sea-level rise due to global warming occurs primarily because water expands as it warms up. The melting ice caps and mountain glaciers also add water to the oceans, thus rising the sea level.  The contribution from large ice masses in Greenland and Antarctica is expected to be small over the coming decades. But it may become larger in future centuries.  Sea-level rise can be offset up by irrigation, the storage of water in reservoirs, and other land management practices that reduce run-off of water into the oceans. Changes in land-levels due to coastal subsidence or geological movements can also affect local sea-levels.
  13. CLIMATE CHANGE AND SEA LEVEL RISE  About 20,000 years ago during the LGM, large ice sheets melted causing a rise in sea level of about 100m, most of the melting occurred about 6,000 years ago.  Over the past 1,000 years and prior to the 20th century, the average global sea level rise was of the order of 0.2 mm/yr.  The rate of sea level rise climbed to about 1-2 mm/yr during the 20th century, with a central value of 1.5 mm/yr (IPCC TAR). The most recent estimate during the 20th century is 1.4 -2.0 mm/yr, with a central value of 1.7 ± 0.3 mm/yr (Church & White, 2006).  This significant rate of rise in sea level is attributed to global warming caused by industrialization during the second half of the 19th century.
  14. CLIMATE CHANGE AND SEA LEVEL RISE  There is no evidence for any acceleration of sea level rise in data from the 20th century data alone. Mediterranean records show decelerations and even decreases in sea level in the latter part of the 20th century.  Most records show evidence of a gradual rise in global mean sea level over the last century. However, signals caused by land movements (e.g. uplift or submergence) can mask this signal due to actual changes in sea level.  The IPCC has estimated that, if the emission of greenhouse gases continues at the current rate, the level of the sea surface will rise by an additional 8-20 cm by 2030, 21-71 cm by 2070 and 31-110 cm by 2100.
  15. Global Sea Level Change Over the Last 140,000 Years (IPCC TAR)
  16. Mean Sea Level Variations at Selected Locations [Data:]
  17. PHYSICAL IMPACTS OF SEA LEVEL RISE PRIMARY IMPACTS  Inundation and displacement of wetlands and lowlands  Increased vulnerability to coastal storm damage and flooding  Shoreline erosion  Saltwater intrusion into estuaries and freshwater aquifers SECONDARY IMPACTS  Altered tidal ranges in rivers and bays  Changes in sedimentation patterns  Decreased light penetration to benthic organisms  Increase in the heights of waves
  18. Inundation and displacement of wetlands and lowlands  This, the most obvious impact of sea level rise, refers both to the conversion of dryland to wetland and the conversion of wetlands to open water.  In salt marsh and mangrove habitats, rapid sea-level rise would submerge land, waterlog soils, and cause plant death from salt stress.
  19. Objective  The assessment of impacts of sea level rise over the next century is hindered by lack of knowledge of the detailed topography of the near shore.  New global elevation maps based on detailed surveys at cm resolution will make it possible to accurately determine the areas which will be inundated by storm surges under conditions of rising sea level.  This will require a concerted effort by the satellite altimetry community as well as local ground-based geodetic surveyors in all coastal areas world-wide.