In this chapter - Increasing risk and toll | Increased vulnerability | Objective comparison of risks

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We have seen, in earlier chapters, how we persist in living in hazardous areas because our perception of hazard threat differs from the reality of that threat, and how we have developed means of coping with and adjusting to environmental stress. In the trade-off between resources (benefit) and hazards (cost) we generally underestimate costs and are unduly optimistic about potential benefits.

Three issues are of key importance; the occurrence of hazard events; our vulnerability to the impacts of those events; and the way we create new technological hazards and alter the risk potential of existing natural hazards.

Whilst we might like to think that there is no net change in the number and impact of extreme natural hazard events world-wide, the evidence (Table 8) suggests otherwise. Many types of hazard event appear to have increased in frequency by over 50 percent between the 1960s and 1970s. The death toll for each type of disaster listed has increased six-fold between 1960s and 1970s (an increase much larger than could be explained in terms of population increase alone). The number of people affected by disasters each year nearly doubled between the 1960s and 1970s. The early indications during the 1980s were that all of these trends were continuing.

SOURCE: data summarised from UNEP (1987)

Natural hazards appear to be becoming more frequent, and more dangerous to humans; yet there is no evidence of significant changes in the geophysical and biological processes which give rise to hazards. Natural environmental processes often trigger disaster events, but they are not always the main cause of them. Much of the increased loss and damage is concentrated in the developing world, and it reflects the interaction of human vulnerability (related to poverty and inequality), environmental degradation (related to poor land-use) and rapid population growth (especially amongst the poor).

Human vulnerability to natural hazards has increased during the present century for a number of reasons. Population expansion and economic development have been key factors.

Population expansion is a major factor because population growth and increased mobility are encouraging growing concentrations of people in hazardous areas. For example, the city of Managua in Nicaragua has been devastated by earthquakes three times in the last hundred years, and then rebuilt in exactly the same place. The population increased from about 45,000 in 1931 to over 400,000 in 1972, despite the proven hazard risk.

Population expansion and settlement in unplanned fashion around major cities is a particular problem in developing countries such as Mexico (Mexico City and the surrounding area is home to roughly 18 million people, about two-thirds of the families living in single rooms). Between 1985 and the year 2000 it is estimated that Third World cities (which housed a billion people in 1980) could grow by another three-quarters of a billion. The poorer people will often be forced to settle in already over-crowded hazardous sites (like unstable hillslopes; deep ravines; even rubbish tips) because land values in safe sites are prohibitively high. This puts them at special risk; the poverty trap keeps them there.

In countries like the United States, population increases coupled with changing lifestyles and levels of income have encouraged much new housing in mobile homes, which can be very vulnerable to damage by natural hazards. Population changes also mean more people living in new and unfamiliar environments, often blissfully ignorant of potential hazard risks and possible ways of coping with them. Suburbanisation has encouraged development on unprotected floodplains, seismic risk areas and exposed coastal sites.

Economic development has also increased vulnerability to hazards, via the evolution of large corporations. Large corporations (particularly multi-nationals) can enlarge their capacity to absorb risks by accumulating large capital reserves, or by diversifying locations of economic activity. This can encourage them to locate plants in high risk areas, and to show reluctance in adopting hazard-resistant building methods. Enhanced employment prospects attract job-seekers, and population increases encourage housing developments so that potential hazard risks are amplified even further.

Vulnerability to hazards is also increased by the process of economic development within an area. During the transition from a traditional economy to a modern high-technology urban-based economy, the lure of rapid economic growth often stimulates profit-seeking development, with a time-lag before provision of infrastructure and methods of coping with hazards are seen as necessary and viable.

The promise of jobs and local revenues from major industrial investments by multi-nationals can sometimes encourage Third World governments to either turn a blind eye to apparent technological risks or to accept below-optimum environmental quality (as part of the cost of attracting the overseas investment). Technology transfer can create massive hazard risks; it is unlikely that the Union Carbide pesticides plant which exploded at Bhopal in 1984 would have been permitted in the USA, for example.

It is difficult to make meaningful comparisons between all possible events and activities which kill and injure humans and damage property and the environment, because the sources of threat are so varied and numerous and our perception distorts reality. We tend to make certain assumptions about relative risks, and often wrongly assume that some hazards are more serious than others.

Loss of life from natural hazards must be placed in context. The 2,600 lives lost as a result of the Vaiont Dam disaster in Italy in 1963 is not substantially higher than the 1,500 who died when the Titanic sank in 1912; the 36,000 lost as a result of the eruption of Krakatoa in 1883 is small in comparison with over 9.5 million who died from famine in China in 1878 (and the high death toll from famine in China in the early 1960s, for which figures are only now becoming available in the west).

Single major natural hazard events (like volcanoes, earthquakes, tropical cyclones, floods, landslides and avalanches, droughts) can kill vast numbers of people (Table 10), but these are the exceptions. Road accidents in the United States kill more people in a typical year (like 1985, Table 9) than most types of hazard world-wide (Table 8). Major industrial accidents can have a large death toll, but this is but a drop in the ocean compared with loss of life in wars and conflicts around the world (Table 9).

SOURCE: summarised from Wijkman and Timberlake (1984)

 Magnitude of loss of life in clearly important, but so is the manner of death. People become accustomed to certain types of death or disaster - familiar causes of death (such as old age) seem less serious than unfamiliar ones (such as cancer possible related to radiation poisoning); regular occurrences(such as vehicle accidents) seem less striking than irregular ones (such as earthquakes); and death seems less acceptable if many die together, or if many of the victims are young.

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Copyright © 1999 Chris Park
Last modified: 17 August 1999