Health impacts associated with population displacement fall under two general categories: health impacts resulting from the new ecological environment and health impacts resulting from the living environment in refugee camps (Prothero, 1994). Even displacement from longer term cumulative environmental deterioration is associated with such health impacts. Cumulative changes that may cause population displacement include land degradation, salinity, deforestation, waterlogging, desertification, and water scarcity. When pastoralists in west Africa were forced to move because of reduced pasture and water, they were faced with new ecological conditions. They experienced psychological stress and were more at risk of infectious diseases (Stock, 1976; Prothero, 1994). Climate change may affect human security via changes in water supplies and/or agricultural productivity (Lonergan, 1998, 1999). An increase in the magnitude and frequency of extreme events also would be disruptive to political stability.
Immediate environmental catastrophes can force sudden displacement of a population.
In these cases, adverse health impacts usually result from living in refugee
camps in overcrowded, poor accommodations with inadequate food, water supplies,
sanitation, and waste disposal (Shears et al., 1985; Noji, 1997). These
conditions predispose people to parasitic and communicable diseases such as
malaria and cholera, respiratory infections, intestinal disorders, malnutrition,
and psychological stress (Prothero, 1994).
The potential impacts of sea-level rise on the health and well-being of coastal populations are an important consideration (Klein and Nicholls, 1999). Estimates of the potential number of people at risk from sea-level rise are addressed elsewhere in TAR WGI and this volume. For example, a 0.5-m rise in sea level along the Nile delta would flood 32% of urban areas, resulting in a significant loss of shelter and forced migration (El-Raey et al., 1999; see Chapter 6). In some locations, sea-level rise could disrupt stormwater drainage and sewage disposal and result in salinization of freshwater supplies. It can affect health indirectly by reducing food productionfor example, by reducing rice production in low-lying coastal rice paddies. Sea-level rise also could affect the distribution of vector-borne diseasesfor example, some of the coastal wetlands of the United States may be flooded, thereby destroying the habitat of the EEE virus. Populations with limited economic, technical, and social resources have increased vulnerability to various infectious, psychological, and other adverse health consequences.
Box 9-3. Understanding El Niño Can Help Adaptation to Climate Change: Seasonal Climate Forecastin
There is evidence of an association between El Niño
and epidemics of vector-borne diseases such as malaria and dengue in
some areas where El Niño affects the climate (Kovats et al.,
1999). Malaria transmission in unstable areas is particularly sensitive
to changes in climate conditions, such as warming or heavy rainfall
(Akhtar and McMichael, 1996; Gupta, 1996; Najera et al., 1998).
In Venezuela and Colombia, malaria morbidity and mortality increases
in the year following the onset of El Niño (Bouma and Dye, 1997;
Bouma et al., 1997b; Poveda et al., 2000). ENSO also has
been shown to affect dengue transmission in some Pacific islands (Hales
et al., 1999b), though not in Thailand (Hay et al., 2000).
However, in many of the studies that have found a relationship between
El Niño and disease, the specific climate drivers or mechanisms
have not been determined. There also are other climate oscillations
that are less well studied. Furthermore, there are other important explanations
of cyclic epidemics, such as changes in herd immunity (Hay et al.,
The ENSO phenomenon provides opportunities for early warning of extreme weather, which could improve epidemic preparedness in the future. Seasonal forecasting methods and information have the potential to be used to far greater effect by the health sector (IRI, 1999; Kovats et al., 1999). In addition to these direct applications, attention to the impacts of interannual climate variability associated with the ENSO phenomenon would help countries develop the necessary capacity and preparedness to address longer term impacts associated with global climate change (Hales et al., 2000). On the other hand, there are limitations to using ENSO interannual climate variability to assess potential impacts of long-term climate change.
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