Small Islands: Climate Change Impacts

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Small Islands: Climate Change Impacts

Introduction

Small islands are particularly vulnerable to the effects of climate change. Most small islands, inhabited and uninhabited, are found in the Pacific Ocean, which contains over 20,000 such islands. Their total area is small, the combined area of the twenty or so independent states, dependencies, and territories that comprise most of the

Pacific islands being less than 38,500 square mi (100,000 square km), smaller than the U.S. state of Kentucky. The total population of the small islands of the Pacific is 5 to 6 million, about two thirds of whom live in Papua New Guinea.

Japan, Hawaii, the Philippines, New Zealand, Tasmania, and the major Indonesian islands are generally treated in a separate class from the smaller islands. Major populations of small islands also exist in the Indian Ocean and the Caribbean. Put simply, small islands are more vulnerable to climate change because there is nowhere to go as the sea rises, nowhere to hide when extreme weather events such as hurricanes arrive. Freshwater exists in precarious balance with the surrounding sea, and declines in fish-eries may decimate ocean-based economies. Small Pacific nations have been particularly vocal in international forums about the need to take action to reduce greenhouse-gas emissions.

Historical Background and Scientific Foundations

Island countries (a term used to include both independent nations and various territories) have been responsible for emitting less than 1% of human-produced greenhouse gases. They have, however, been acutely conscious of the effects of sea level rise, which has occurred at a rate of about 0.08 in (2 mm) per year throughout the twentieth century. According to the United Nations Intergovernmental Panel on Climate Change's 2007 report, world sea level could rise as much as 23 in (58 cm) by 2100. Moreover, this calculation does not take into account the possibility of accelerated melting of the Greenland and portions of the Antarctic ice sheets: actual melting could be more, or less, than 23 in (58 cm).

In 2007, the IPCC released the report of its Working Group II, Climate Change 2007: Impacts, Adaptation

and Vulnerability. The report noted the following points, among others, about the impacts of climate change on small islands:

Small islands are especially vulnerable to the effects of climate change, including sea-level rise and extreme weather events. In most cases, small islands have fragile economies and the costs of adapting to climate change—where adaptation is possible at all—are high compared to the size of the local economy. In other words, most small islands cannot afford to do much about climate change.
Rising sea levels will submerge territory and worsen storm surge (high water during storms) and erosion, threatening settlements and infrastructure that support livelihood. In Caribbean and Pacific islands, over half the population lives within a mile (about 1.6 km) of the shoreline, and most roads, airports, capital cities, and the like are located along the coast or on very small coral islands that are essentially all coast. Because most small islands do not rise steeply from the sea and may only be a few feet, or meters, above sea level at their highest point, all these facilities can be threatened by even apparently small increases in sea level.
Freshwater resources on most small islands will be seriously reduced in most future climate-change scenarios. On a small island, fresh groundwater exists in a lens-shaped volume of ground surrounded by undrinkable saltwater. Two effects of climate change can contribute to reducing the size of this lens—rising sea level and reduced rainfall. Rising seas shrink the freshwater lens by mixing seawater with it at its boundaries and base. Reduced summer rainfall is predicted for the Caribbean. On the Pacific atoll of Tarawa, a predicted 10% reduction in rainfall by 2050, if it occurs, will cause a 20% shrinkage of the freshwater lens.
Tourism, fisheries, agriculture, and human health will be adversely affected by climate change. For example, coral reefs are already being destroyed by warmer temperatures in tropical waters around the world. Fish populations and thus fish catches by island populations decline sharply when coral reefs shrink.

Impacts and Issues

The threat of complete erasure is quite real for low-altitude small islands, such as those formed by coral atolls and in river deltas. For some inhabitants of such islands, it is not a future possibility but a fact of experience. In one of the world's largest collections of river delta islands, the Sundarban islands in India, formed by the spreading outflow of the Ganges river, some 31 sq mi (80 sq km) of land have vanished over the last 30 years due to rising water.

Rising levels have been compounded in the river delta by increased outflow from Himalaya glaciers upstream, whose accelerated melting is possibly another result of global warming. Several islands have vanished completely, and over 600 families have been displaced.

WORDS TO KNOW

ATOLL: A coral island consisting of a ring of coral surrounding a central lagoon. Atolls are common in the Indian and Pacific Oceans.

GREENHOUSE GASES: Gases that cause Earth to retain more thermal energy by absorbing infrared light emitted by Earth's surface. The most important greenhouse gases are water vapor, carbon dioxide, methane, nitrous oxide, and various artificial chemicals such as chlorofluorocarbons. All but the latter are naturally occurring, but human activity over the last several centuries has significantly increased the amounts of carbon dioxide, methane, and nitrous oxide in Earth's atmosphere, causing global warming and global climate change.

RIVER DELTA: Flat area of fine-grained sediments that forms where a river meets a larger, stiller body of water such as the ocean. Rivers carry particles in their turbulent waters that settle out (sink) when the water mixes with quieter water and slows down; these particles build the delta. Deltas are named after the Greek letter delta, which looks like a triangle. Very large deltas are termed megadeltas and are often thickly settled by human beings. Rising sea levels threaten settlements on megadeltas.

STORM SURGE: Local, temporary rise in sea level (above what would be expected due to tidal variation alone) as the result of winds and low pressures associated with a large storm system. Storm surges can cause coastal flooding, if severe.

WATER LENS: Body of fresh groundwater retained by a small ocean island. Rising sea levels shrink an island's water lens and may eliminate it.

Further, increased intensity of cyclones (the general term for “hurricanes,” which strictly refers only to cyclonic storms in the Atlantic ocean), also a predicted result of climate change, has accelerated erosion of the islands. The IPCC has rated the Sundarban ecosystem as one of the world's most vulnerable to climate change. As climate change proceeds, such stories will be told of other inhabited small islands.

BIBLIOGRAPHY

Books

Parry, M.L., et al, eds. Climate Change 2007: Impacts, Adaptation and Vulnerability: Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. New York: Cambridge University Press, 2007.

Periodicals

Sengupta, Somini. “Sea's Rise in India Buries Islands and a Way of Life.” The New York Times (April 11, 2007).

Tompkins, Emma L. “Planning for Climate Change in Small Islands: Insights from National Hurricane Preparedness in the Cayman Islands.” Global Environmental Change 15 (2005): 139–149

Web Sites

“Climate Change and the Pacific Islands.” United Nations Economic and Social Commission for Asia and the Pacific, Ministerial Conference on Environment and Development in Asia and the Pacific, 2000. <http://www.unescap.org/mced2000/pacific/background/climate.htm> (accessed September 16, 2007).

Larry Gilman

Climate Change: In Context