Climate Change drivers and possible Impacts in PERSGA Region
There are some indications that a number of ecological changes experienced in the region during the last decades are probably linked to the impacts of climate change e.g. increased frequency and duration of drought episodes, El-Nino induced coral bleaching in the southern parts of the Red Sea in 1998, mangrove dry-up at several stands in the Gulf of Aden and southern parts of the Red Sea coast, etc. Furthermore, the current development patterns in the coastal zones are likely increasing coastal vulnerability to climate change impacts. A synopsis of climate change drivers and their likely impacts on the coastal and marine environments of the Red Sea and Gulf of Aden may include:
The direct effect of sea level rise is land loss through inundation of low-land inhabited areas, wetlands and low-lying islands along the coast. Sea-level rise will also allow waves to cover the coral reefs, increasing the coastal vulnerability to erosion and storms. Consequently, shore-line retreat from sea-level rise could be greater than from inundation alone. In such conditions, risks will be enormous including recreational beaches, major resorts, human settlements, infrastructure & facilities (including harbors, pipelines, terminals etc.), heritage areas, wildlife and coastal resources.
Warmer seawater temperatures
Warmer seawater temperatures have potential impacts on distribution patterns of marine organisms, and can lead to increased frequency of coral bleaching. Increased temperatures will also induce changes in oceanic parameters, chemistry of seawater, trends of water movements (currents), waves and evaporation rates. The Red Sea habitats and their communities generally exist at their biogeographically known eco-zone boundaries, and they appear to be living in conditions close to their physiological limits. For this reason shifts in temperature ranges might persuade relatively more vigorous changes in the Red Sea biotopes.
Increased carbon dioxide concentrations in seawater
Increase CO2 concentrations will be altering seawater chemistry, causing water acidification and making it difficult for calcitic organisms such as corals to grow and function. Seawater acidification might also have severe impacts on marine life affecting their physiology, behavior and reproduction.
Change in run-off reaching the coastal and marine system
This will be associated with the likely changes in climate over land. It will have implications on productivity, distribution of coastal vegetation (including mangroves), coral reefs (through increased depositions), and intensity of flash floods or drought epochs striking the coastal area.
Alteration in patterns of coastal currents, winds and waves
The combined effect of sea-level rise, warming air / seawater, and shifts in climatic parameters might induce changes in typical monsoonal trends, coastal currents, waves and winds, resulting in extreme events such as high waves and storms on coastal areas.
Impact on water supply
Water supplies along the arid coastal area of the Red Sea and Gulf of Aden are already under stress. Intrusion of saline water from sea-level rise and the anticipated changes in precipitation rates will cause additional stress on water supplies.
Changes in major fisheries and aquaculture
Potential changes in ecosystem including important breeding and nursery habitats for commercial fishes (such as mangroves, sheltered bays, seagrass beds and coral reef) will have impacts on major fisheries.
Possible health impacts include stress from summer heat waves, outbreak of water-born and thalassogenic diseases, changes in distribution of vectors and epidemiology of transmitted diseases, and stresses from disasters and severe incidences (such as storms and floods).
These may include impacts of climate change on infrastructure and social system, income generation and distribution in rural and urban communities in the coastal zone; as consequences of land and heritage loss, decline in ecosystem services (e.g. fisheries, tourism), property rights issues, and change in general socioeconomic patterns in the coastal zone.
The Regional Organization for the Conservation of the Environment in the Red Sea and Gulf of Aden