Lessons from the past |
THE PURPOSE of this section is to examine whether any trends can be recognized
in disasters that have involved coasts and population over recent decades.
There are several databases on disasters, usually focusing on specific themes.
A brief introduction to the subject is given by IFRCS, 1996. For the current
study, we adopted the database assembled by the Office of the US Foreign
Disaster Assistance, among others because all types of disasters are covered.
Information is more complete on the events since 1964 (OFDA, 1996), and the
records exclude disasters within the US and its territories. Basically it
includes only "major" disasters, based on losses and number of people affected,
homeless or killed. The criteria are less strict for small island countries,
with the consequence that they tend to be over-represented.
Table 4 below quantifies the loss of life associated with disasters this
century. Disasters have been grouped in categories as follows:
"Sea" (555 disasters), caused by extreme factors associated with the seas
and oceans, mainly tropical cyclones, hurricanes, tsunamis and typhoons)
"Land" (1918 disasters) including avalanches, cold waves, drought,
earthquakes, fires, floods, heat waves and landslides)
"Population": (1043 disasters) mostly events due to war and diseases,
including internally displaced persons and refugees, epidemics, famine
and food shortage
"Others": (322 disasters) covering power shortages, storms, volcanic
eruptions  and unusual phenomena.
Table 4. Number
of people killed per disaster and number per disaster per million
world population. 1940-1995 data
Derived from OFDA, 1996. Refer to the text for the types of disasters covered
by the "Sea", "Land", "Population" and "Other" categories.
|Number of disasters
|Dead/disaster per million pop.
It appears that man-made "population" disasters tend to create more victims
than both sea and land-bound disasters. As an example, wars and political
disputes have, over the recent decades, replaced drought as one of the
main causes of food shortages. Again, note the marked positive skew of
the distribution of all types of disasters.
The years since 1964  have witnessed an upward trend in population
and land-bound disasters. Sea-bound disasters have shown a positive,
but much less marked, trend as well, with a drop around 1990. Figure 6
shows the relative importance of the four categories: as noted, population-related
disasters have been on the increase , while coastal areas have been losing
importance as disaster areas. This is difficult to reconcile with the
hypothesis that growing populations along the coasts would have become
more vulnerable than in the past, particularly if one considers that the
124 million people living in the 15 main cities in 1965 (New York, Tokyo,
Shanghai, London, Paris, Beijing, Buenos Aires, Los Angeles, Osaka, Mexico,
Moscow, Essen, Chicago, Sao Paulo, Calcutta) constituted a significantly
less "coastal" and vulnerable "environment" target for extreme events than
the current 220 million persons living in the mostly coastal megacities.
Furthermore, cities evolve over time, and in many cases could be expected
to adjust to gradual change in sea-level over the next century - of course
up to certain limits impossible to specify.
If methodological problems and sampling problems can indeed be excluded
(see, for instance Pielke and Landsea, 1997), and provided epidemics,
famine, etc. are not concentrated in the main world urban centres, one
is bound to assume that cities, even coastal ones, constitute a rather
Annual number of disasters by category
Based on data in OFDA, 1996
Total annual damage in 1992 constant US$ due to the "land"
and "sea" based disasters, together with their linear trends
Based on data from OFDA (1996) and the implicit price deflator (Umich, 1997)
In Figure 6, an attempt was made to extrapolate the total annual damage
due to "land" and "sea" disasters. Extrapolations of this kind have a
large statistical variation, but they illustrate the fact that it is
mainly the increase in wealth which leads to increased damage, rather
than the increased frequency of disasters. In addition, there is no
indication as to whether the "wealth structure" (wealth is now mainly
concentrated in buildings and infra-structure, and to some extent in
land) will not undergo significant qualitative changes (for instance,
wealth could be in electronic equipment, or databases, knowledge etc.).
Average number of annual disasters by category.
7. Volcanoes tend to be along the coasts, and many small islands are
actually of volcanic origin, but there is no absolute association.
8. The trends exist before 1964, but only the period after 1964 is
covered because observations are more complete beginning around that year.