The Influence of Climate Variation and Change on Diarrheal Disease in the Pacific Islands
Singh, Reena B. K., Hales, Simon, de Wet, Neil, Raj, Rishi, Hearnden, Mark, Weinstein, Phil, Environmental Health Perspectives
Freshwater resources are a high-priority issue in the Pacific region. Water shortage is a serious problem in many small island states, and many depend heavily on rainwater as the source of their water. Lack of safe water supplies is an important factor in diarrheal illness. There have been no previous studies looking specifically at the relationship between climate variability and diarrhea in the Pacific region. We carried out two related studies to explore the potential relationship between climate variability and the incidence of diarrhea in the Pacific Islands. In the first study, we examined the average annual rates of diarrhea in adults, as well as temperature and water availability from 1986 to 1994 for 18 Pacific Island countries. There was a positive association between annual average temperature and the rate of diarrhea reports, and a negative association between water availability and diarrhea rates. In the second study, we examined diarrhea notifications in Fiji in relation to estimates of temperature and rainfall, using Poisson regression analysis of monthly data for 1978-1998. There were positive associations between diarrhea reports and temperature and between diarrhea reports and extremes of rainfall. These results are consistent with previous research and suggest that global climate change is likely to exacerbate diarrheal illness in many Pacific Island countries. Key words: climate change, diarrheal disease, epidemiology, Pacific islands, rainfall, temperature, water resources. Environ Health Perspect 109:155-159 (2001). [Online 24 January 2001] http://ehpnet1.niehs.nih.gov/docs/2001/109p155-159singh/abstract.html
Freshwater is a renewable but finite resource. The scale of its development and use therefore must not exceed certain limits if the ecologic balance is to be maintained (1). These limits are generally determined by the rates of recovery--that is, both the regenerative rate of the hydrologic cycle as well as the assimilative capacities of receiving water bodies (2). The main principles for the sustainable development of the water resources are that the rate of extraction from both ground and surface water resources should not exceed the rate at which the resource is renewed and extraction must not seriously compromise the health and biodiversity of the ecosystem (2-4). For example, the extraction of surface water upstream should not affect water quality and biodiversity of river ecosystems downstream.
According to the Intergovernmental Panel for Climate Change (IPCC), in almost all countries in Asia and the Pacific, there have been growing environmental problems due to unsustainable use and development of water resources (3). Water pollution has become a major environmental problem, and excessive use of groundwater is adversely affecting the availability of safe drinking water in some countries. The IPCC stresses the vulnerability of small islands to increasing amplitudes and frequency of high tides, greater wave damage, and intrusion of salt water into the islands' underground freshwater lens (3). On high islands, changes in rainfall patterns either from interannual variations due to El Nino Southern Oscillation (ENSO) or a changed climate regime have caused severe shortages of water (3-5).
Sea level rise is a significant climate-related change anticipated to affect small islands, especially in low-lying island states and atolls such as Tokelau, Kiribati, Tuvalu, and the Marshall Islands (5).
Because of these problems, management of drinking water resources is a high priority in the region (4). In many island countries, the differential between wet and dry season rainfall is in the order of 80:20%. Consequently, small islands often have serious water shortages in the dry season. The total volume of rainfall on small atolls is low, and most of it is lost through evapotranspiration and runoff. Although many high islands have high rainfall, they are mostly volcanic and seldom have the geomorphology necessary for good water retention. …