sea-levelRise
According to the fourth assessment report (FAR) of the Intergovernmental Panel on Climate Change (IPCC), global sea level rose at an average of 1.8mm/yr from 1961 to 2003, and at an average of 3.1mm/yr from 1993 to 2003. What causes sea levels to rise? Since 1997, the thermal expansion has contributed to 57% to sea level rise, the decrease in glacier and ice caps about 28%, and the loss of polar ice sheets 15%. The principal reason is, thus, the increase in average temperatures (air and ocean), which was exacerbated by anthropogenic greenhouse gases (GHGs) emissions.
Sea level rise is a serious concern for islands, particularly small island states with whom Islands First works. Island settlements have many features in common, one of which is the high proportion of coastal settlements. In the Pacific or Caribbean islands, for instance, over 50% of the population is located within 1.5km of the shore, and all major infrastructures, such as airports, or economic activities are also in floodable areas on the coast. As a result, they are highly vulnerable to a rise in sea level. Tuvalu, for example, is cut from the world up to 2 weeks a year during the high tide seasons which completely flood the island of Funafuti and its airport strip.
Sea level rise will affect these societies in many levels. First, coastal flooding will increase. This would trigger increased erosion of coastal land surfaces. According to scientific studies, islands with substantial human modification (modern infrastructures for example) are much more vulnerable to coastal erosion, as the natural ecosystems have been replaced by modern structures and can no longer fulfill their ecological roles.
What is more, as most infrastructures are on the coast, the damages from erosions and flooding are likely to be burdensome for these fragile economies. As traditional housing and building have been replaced with modern structure, the cost to repair the damages has increased. What is more, mitigation measures against sea level rise, such as building sea walls, are extremely costly especially for islands part of the Least Developed Countries list.
Another negative effect of sea level rise is increased salinity of soils and contamination of fresh water aquifers. As a result, agricultural output, especially from traditional crops, is likely to decrease. This is a serious threat especially since population is increasing. What is more, as salt water enters further in the islands, freshwater lenses and freshwater aquifers will increasingly be contaminated by salt water leading to water scarcity. This is particularly problematic since this phenomenon will be combined with the likely decrease in precipitation. Many islands are starting to invest in desalinization plants. However, their high cost is prohibitive for many islands who cannot afford to invest in these life saving infrastructures without outside financial help.
The previsions are not optimistic. The projected increase ranges from 0.19 to 0.58m by the end of the 21st century relative to 1980-1999. This increase is, of course, very problematic for islands, such as the Maldives, Tuvalu, Kiribati, and other atoll formed nations, that culminate at 3 meters. Tide phenomena, thermal expansion, and extreme weather events will contribute to making life in these islands increasingly difficult, if not impossible.