Extreme events over time - Extreme Events: A Physical Reconstruction and Risk Assessment - page 266

40
35
30
25
20
15
10
5
0

70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 00 02

Year

Natural disasters
Human-made disasters

Figure 10.6. Insured losses from both natural and human-induced hazards (from
Swiss ReInsurance).

record may predict an appropriate and safe position for a development with
respect to hazard exposure if the hazard regime remains the same for the next
50 or more years. However, this cannot be predicted with any certainty until the
nature of any hazard regime shifts and variable probabilities are known. This
requires knowledge of the long-term variability of the hazard in question. With-
out such knowledge it is prudent to assume that a shift to a more active hazard
regime is possible within the lifespan of the planning period. When, however,
knowledge of the long-term variability is obtained and the variations in proba-
bilities are determined, it is up to planners and policy makers to use their own
judgments on where they intend to set the level of risk for community safety.
This of course is always subject to a range of different economic and political
forces. However, it will always be prudent to adopt the precautionary principle
especially when it may be uncertain exactly where the present day lies on the
probability cycle.

Future climate change and natural hazards

Globally, insured losses from natural hazards have increased substan-
tially over the past 40 years (Fig. 10.6). While it is obvious that increasing popu-
lation and community vulnerability will account for most if not all of this trend
it will also be tempting for many to suggest that global climate change may be at
least playing a role resulting in an increase in actual hazard events. Predictions
from global climate models suggest that the magnitude and in some instances
thefrequency of atmospherically generated hazard events will increase. The