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4.5 Sea level rise
Projected rise in sea level will have significant impacts on coastal areas, especially mega cities in coastal areas such as Banjul in the Gambia showed in the figure.
  1. Banjul and many other cities along Africa 's coasts are densely populated, and measures to reduce vulnerability such as through rezoning and new building codes are not immediately possible given the impossibility of moving infrastructures that already exist.
    Coastal erosion is already a major problem in many areas.


    Graphic: UNEP/GRID-Arendal

  1. Bangladesh
    one of the world's poorest nations is also the country most vulnerable to sea-level rise.
    The population is already severely affected by storm surges.
    Catastrophic events in the past have caused damage up to 100 km inland. It is hard to imagine to what extent these catastrophes would be with accelerated sea-level rise.

    Digital terrain modeling techniques have been used to display the Bangladesh scenarios.
    A three dimensional view of the country has been overlaid with the current coastline and major rivers and potential future sea levels at 1.5 meters.

    Graphic: UNEP/GRID-Arendal
  1. The Nile delta
    is one of the oldest intensely cultivated areas on earth.
    It is very heavily populated, with population densities up to 1600 inhabitants per square kilometer.
    Deserts surround the low-lying, fertile floodplains.
    Only 2,5% of Egypt 's land area, the Nile Delta and the Nile Valley , is suitable for intensive agriculture.
    Most of a 50 km wide land strip along the coast is less than 2 m above sea level and is protected from flooding by a 1 to 10 km wide coastal sand belt only, shaped by discharge of the Rosetta and Damietta branches of the Nile .

    Erosion of the protective sand belt is a serious problem and has accelerated since the construction of the Aswan Dam.

    Rising sea levels would destroy weak parts of the sand belt, which is essential for the protection of lagoons and the low-lying reclaimed lands.
    The impact would be very serious. One third of Egypt 's fish catches are made in the lagoons.
    Sea level rise would change the water quality and affect most fresh water fish.
    Valuable agricultural land would be inundated.
    Vital, low-lying installations in Alexandria and Port Said would be threatened.
    Recreational tourism beach facilities would be endangered and essential groundwater would be salinated.
    Dykes and protective measurements would probably prevent the worst flooding up to a 50 cm sea level rise.
    However, it would cause serious groundwater salination and the impact of increasing wave action would be serious


    Graphic: UNEP/GRID-Arendal
  1. After CO2 emissions are reduced and atmospheric concentrations stabilize, surface air temperature continues to rise by a few tenths of a degree per century for a century or more.
    Thermal expansion of the ocean continues long after CO2 emissions have been reduced, and melting of ice sheets continues to contribute to sea-level rise for many centuries.
    This figure is a generic illustration for stabilization at any level between 450 and 1,000 ppm, and therefore has no units on the response axis.
    Responses to stabilization trajectories in this range show broadly similar time courses, but the impacts become progressively larger at higher concentrations of CO2 .

    See a short video from a Pacific island on impact of sea level rise


    Graphic: UNEP/GRID-Arendal
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The Greenhouse effect, Climate Change and the road to sustainability
1. 1 Greenhouse effect
2. 2 Science
3. 3 Mitigation
4. 4 Impacts
5. 5 Solutions?