Geoscience Reference
In-Depth Information
500
Exponential trend line
400
300
200
100
0
1900
1920
1940
1960
1980
2000
Year
Reporting incidence of natural hazards over time 1900-2001 (based on CRED, 2002).
Fig. 1.2
time span from around ten events per year at the begin-
ning of the century to over 450 events at the end. While
increased vigilance and perception of natural hazards
accounts for part of this increase, other data suggest that
natural hazards are on the increase. The fact that these
figures include both geological and climatic hazards
rules out such a simple explanation as global warming as
a major cause of this increased incidence. On the other
hand, these figures should be treated with some caution
because they do not always hold under scrutiny. For
example, in the United States, the magnitude and fre-
quency of thunderstorms, hailstorms, intense tornadoes,
hurricanes and winter storms have not increased, but
may have decreased. Over the same period, there is no
increase in the cost of climatic hazards after the figures
are adjusted for inflation. Instead, damaging events
appear to recur at twenty-year intervals around
1950-1954, 1970-1974, and 1990-1994. This timing
coincides with the peak of the 18.6
M
N
If famine is removed from the data set, this number
declines to 140 200 deaths per year. This reduction
suggests that famine kills 134 800 people per year,
roughly 50 per cent of the total number. Although the
greatest number of deaths occurred in the 1930s - a
figure that can be attributed to political upheaval and
civil war - there is no significant variation over the
twentieth century. This fact suggests that improved
warning and prevention of natural hazards has
balanced population increases resulting in a constant
death toll. Many world organizations would consider
several hundred thousand deaths per year due to
natural hazards as unacceptable.
Table 1.3 presents the accumulated number of
deaths, injuries and homeless for each type of hazard
for the twentieth century. Also presented is the largest
event in terms of death for each category. The greatest
hazard during the twentieth century was flooding;
however much of this was due to civil unrest. Half
of the 6.9 million death toll occurred in China in
the 1930s where neglect and deliberate sabotage
augmented deaths. Earthquakes and tropical cyclones
account for the other significant death tolls of the
twentieth century. Interestingly, during the first three
years of the twenty-first century 4242 deaths were
caused by cold waves. This is 60 per cent of the total
for the whole of the twentieth century despite the per-
ception of global warming. In contrast, the death toll
from a heat wave in France in 2003 resulted in 15 000
lunar cycle
,
which will be described in Chapter 2.
Figure 1.3 presents the number of deaths due to
natural hazards over the twentieth century. The time
series does not include biological hazards such as epi-
demics or insect predation; however, it does include
drought-induced famines. The number of deaths is
plotted on a logarithmic scale because there have been
isolated events where the death toll has exceeded the
long-term trend by several million. On average 275 000
people have died each year because of natural hazards.
