How are island communities threatened?
Islands have characteristics which make them especially vulnerable to the effects of climate change, sea-level rise and extreme events.
Deterioration in coastal conditions, for example through erosion of beaches and coral bleaching, is expected to affect local resources (e.g., fisheries) and reduce the value of these destinations for tourism.
Sea-level rise is expected to exacerbate inundation, storm surge, erosion and other coastal hazards, thus threatening vital infrastructure, homes and businesses, and other facilities that support the livelihood of island communities. Very large sea-level rises that would result from widespread deglaciation of Greenland and the West Antarctic ice sheets, coupled with the thermal expansion of the ocean, imply major changes in coastlines and ecosystems, and inundation of low-lying areas. Relocating populations, economic activity, and infrastructure will be costly and challenging.
Climate change is projected by mid-century to reduce water resources in many small islands, especially in the Pacific and Caribbean regions, to the point that they become insufficient to meet demand during low-rainfall periods. Furthermore, there is increasing evidence that some weather events (e.g., tropical cyclones) and extremes (e.g., floods and droughts) will become more frequent, more widespread and/or more intense due to global warming.
The impacts of climate change will vary regionally, and they are very likely to impose net annual costs that will increase over time as global temperatures increase. Therefore, there is urgent need for a targeted climate adaptation policies for all island communities, which must be a joint effort of climate scientists, policy-makers and local organizations.
- For additional information on the climate change impacts on island communities see the “Regional Climate Impacts: Islands” section of the US Global Change Research Program’s Global Climate Change Impacts in the United States (2009).
The climate issue has become highly-charged in recent years and public opinion and the news media are filled with disparate and confusing explanations. Simply stated, climate changes if the Earth changes, that is if the planet’s characteristics are altered as result of the action of internal or external factors.
Yet, to reply to this question in a more complete way, it is important to first answer another question: what is climate? Climate is rather difficult to define because it involves factors from the smallest oceanic microorganism to the Earth’s astronomical configuration.
Climate is not weather, though the two are often confused. The weather in a certain location is the state of the atmosphere (characterized by temperature, precipitation, humidity, wind, pressure, etc.) at a particular time. The average weather over a time period of some years (at least 30, as defined by the World Meteorological Organization) is the climate of a specific location.
However, the atmosphere, and therefore weather, are influenced by the other components of the Earth system: ocean, land surface, biosphere, and cryosphere (ice). Therefore the state of Earth’s climate also includes the state of those elements. All of the Earth’s subsystems are connected with each other, hence a change in one of them has consequences on all the others. So, it is easy to understand the difficulties of predicting how climate can change in the future.
Since the beginning of Earth’s history, climate has always been in perpetual evolution, due to natural forcing. The ultimate source of natural climate change is Earth’s position with respect to the Sun. The solar radiation reaching the Earth’s surface is not evenly distributed in space and time, due to the movement of the planet. In particular periodic changes in the Earth’s orbit over hundreds of thousands of years gives origin to the ice ages and the inter-glacial eras (the warm periods between ice ages). Climate can also change as a result of tectonic movements (the movements of Earth’s crust), as well as to changes in the atmospheric composition (the concentration of greenhouse gases and dust).
Over the last two centuries, roughly since the Industrial Revolution, humans have also been contributing to climate change mostly by the continuous burning of fossil fuels and the extensive use of land and ocean resources (anthropogenic forcing). We know that the current climate change is human-induced because it is happening extremely fast (on geological time scales!) and climate models cannot reproduce it without adding anthropogenic forcing to natural forcing. According to the Intergovernmental Panel for Climate Change (IPCC), present and future climate change arises from the complex interaction between human and natural systems, socio-economic development and the associated emission of greenhouse gases.
Climate change can have dramatic consequences on both natural ecosystems and human societies, thus policies that limit human contributions to climate change and help communities adapt to the inevitable changes underway are necessary to avoid catastrophes and to protect the planet’s inhabitants.
- To learn more about the consequences of climate change on society, please read the Summary for Policy-makers of the IPCC’s Working Group II Assessment Report 4 (AR4) on “Impacts, Adaptation and Vulnerability” (2007).