Natural hazards the human dimension

The impact of natural hazards on society is clearly on the rise, although it still falls far below that due to environmental degradation and, in particular, civil strife (Fig. 8.1). Figures for the period 1900-90 indicate that almost 90 per cent of disaster-related deaths over the period can be attributed to war and famine, with all the natural hazards together making up the remainder. Notwithstanding this, the numbers of people affected by natural hazards during the 1970s and 1980s fell little short of a billion - somewhere between a fifth and a quarter of the Earth's population. With over 250 million people being affected by the 1996 and 1998 Chinese floods alone, similar figures for the last decade of the millennium are likely easily to top the billion mark. The increasing impact of natural hazards over the past halfcentury is without doubt linked to rapidly rising populations in particularly vulnerable regions. At greatest risk are the poorest inhabitants of developing countries, forced to live on marginal land in coastal zones and around cities. Around 50 per cent of the Earth's 6 billion inhabitants are now urban dwellers. For historical and geographical reasons, large and growing numbers of these people are

All other hazards (including raturai hazards and epidemics) 13%

All other hazards (including raturai hazards and epidemics) 13%

Figure 8.1 Breakdown of disaster-related deaths 1900-90. (After Blaikie et al, 1994)

concentrated in coastal environments, where flat land permits the rapid expansion of urban centres, and an estimated 75 per cent of the population of coastal zones now reside in towns and cities. Unfortunately, coastal environments are also the most vulnerable to natural hazards, and particularly the flooding associated with windstorms and tsunami caused by offshore earthquakes. Because of the common coincidence of coastlines and plate margins, volcanic eruptions and earthquakes often pose an additional threat. The Earth's population is currently growing at around 90 million people a year, with the largest increases concentrated in developing countries. Currently, 96 per cent of all deaths due to natural hazards and environmental degradation occur in developing countries, and this situation is unlikely to change as the rate of urbanisation increases in the most vulnerable regions. In 2007, for the first time more people will live in cities and towns than in the countryside. A little over 15 per cent of the planet's population currently live in megacities (defined as having populations in excess of 8 million people) and by 2020 this figure is expected to have climbed to over 30 per cent. As shown in Fig. 8.2 and Table 8.1, most of this increase will be accommodated by the growth of cities in developing countries characterised by low income and high sensitivity to natural hazards. Assuming a projected population by this time of between 7 and 8 billion, this places over 2

High

Income

Figure 8.2 Predicted growth of large (3-8 million) cities and megacities (>8 million). Megacities shaded. Many of the most rapidly growing population concentrations are in developing countries that are most vulnerable to natural hazards.

Figure 8.1 Breakdown of disaster-related deaths 1900-90. (After Blaikie et al, 1994)

High

Income

Figure 8.2 Predicted growth of large (3-8 million) cities and megacities (>8 million). Megacities shaded. Many of the most rapidly growing population concentrations are in developing countries that are most vulnerable to natural hazards.

Table 8.1 The ten most populous cities in the world in 1950 and 2015 (predicted). Reproduced with permission from Munich Reinsurance Group, major natural catastrophes from the 11th to the 19th century. MRNat Catservice, December 1999.

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