IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group II: Impacts, Adaptation and Vulnerability

16.4 Key future impacts and vulnerabilities

The special characteristics of small islands, as described in Section 16.2.1, make them prone to a large range of potential impacts from climate change, some of which are already being experienced. Examples of that range, thematically and geographically, are shown in Box 16.1. Further details on sectors that are especially vulnerable in small islands are expanded upon below.

Box 16.1. Range of future impacts and vulnerabilities in small islands

* Numbers in bold relate to the regions defined on the map

Region* and system at risk Scenario and reference Changed parameters Impacts and vulnerability 
1. Iceland and isolated Arctic islands of Svalbard and the Faroe Islands: Marine ecosystem and plant species  SRES A1 and B2 ACIA (2005)  Projected rise in temperature 
  • The imbalance of species loss and replacement leads to an initial loss in diversity. Northward expansion of dwarf-shrub and tree-dominated vegetation into areas rich in rare endemic species results in their loss.
  • Large reduction in, or even a complete collapse of, the Icelandic capelin stock leads to considerable negative impacts on most commercial fish stocks, whales, and seabirds.
2. High-latitude islands (Faroe Islands): Plant species  Scenario I / II: temperature increase / decrease by 2°C. Fosaa et al. (2004)  Changes in soil temperature, snow cover and growing degree days 
  • Scenario 1: Species most affected by warming are restricted to the uppermost parts of mountains. For other species, the effect will mainly be upward migration.
  • Scenario II: Species affected by cooling are those at lower altitudes.
3. Sub-Antarctic Marion Islands: Ecosystem  Own scenarios Smith (2002)  Projected changes in temperature and precipitation 
  • Changes will directly affect the indigenous biota. An even greater threat is that a warmer climate will increase the ease with which the islands can be invaded by alien species.
4. Mediterranean Basin five islands: Ecosystems SRES A1FI and B1 Gritti et al. (2006)  Alien plant invasion under climatic and disturbance scenarios 
  • Climate change impacts are negligible in many simulated marine ecosystems.
  • Invasion into island ecosystems become an increasing problem. In the longer term, ecosystems will be dominated by exotic plants irrespective of disturbance rates.
5. Mediterranean: Migratory birds (Pied flycatchers – Ficedula hypoleucaNone (GLM/ STATISTICA model) Sanz et al. (2003)  Temperature increase, changes in water levels and vegetation index 
  • Some fitness components of pied flycatchers suffer from climate change in two of the southernmost European breeding populations, with adverse effects on reproductive output of pied flycatchers.
6. Pacific and Mediterranean: Siam weed (Chromolaena odorataNone (CLIMEX model) Kriticos et al. (2005)  Increase in moisture, cold, heat and dry stress 
  • Pacific islands at risk of invasion by Siam weed.
  • Mediterranean semi-arid and temperate climates predicted to be unsuitable for invasion.
7. Pacific small islands: Coastal erosion, water resources and human settlement SRES A2 and B2 World Bank (2000)  Changes in temperature and rainfall, and sea-level rise 
  • Accelerated coastal erosion, saline intrusion into freshwater lenses and increased flooding from the sea cause large effects on human settlements.
  • Less rainfall coupled with accelerated sea-level rise compound the threat on water resources; a 10% reduction in average rainfall by 2050 is likely to correspond to a 20% reduction in the size of the freshwater lens on Tarawa Atoll, Kiribati.
8. American Samoa; 15 other Pacific islands: Mangroves Sea-level rise 0.88 m to 2100 Gilman et al. (2006)  Projected rise in sea level  
  • 50% loss of mangrove area in American Samoa; 12% reduction in mangrove area in 15 other Pacific islands.
9. Caribbean (Bonaire, Netherlands Antilles): Beach erosion and sea turtle nesting habitats  SRES A1, A1FI, B1, A2, B2 Fish et al. (2005)  Projected rise in sea level 
  • On average, up to 38% (±24% SD) of the total current beach could be lost with a 0.5 m rise in sea level, with lower narrower beaches being the most vulnerable, reducing turtle nesting habitat by one-third.
10. Caribbean (Bonaire, Barbados): Tourism None Uyarra et al. (2005)  Changes to marine wildlife, health, terrestrial features and sea conditions  
  • The beach-based tourism industry in Barbados and the marine diving based ecotourism industry in Bonaire are both negatively affected by climate change through beach erosion in Barbados and coral bleaching in Bonaire.