Taxonomy is the process of classifying things or concepts and is usually backed by principles. The study of disasters is a 'lateral discipline' that, to varying degrees embraces at least 42 other disciplines and professions (Alexander 2013). One result of having so many disciplinary perspectives is virtually to preclude consensus on the definition and classification of disasters and the concepts that go with them. NOr is it easy to find a set of common principles to underpin the classification. Hence, disaster studies has resisted taxonomy and perhaps is not amenable to any robust form of classification. However, the purpose of this note is to clarify, or at least explore, some of the issues. One of these is how we break down disasters into categories for the purpose of classifying them. Another is now we define the limits of the study of disasters.
Disaster is fundamentally a social phenomenon. While
not independent of the magnitude of physical forces involved, it is not
linearly related to them because it depends on the nature and size of the
vulnerabilities that the physical forces act upon. Tierney (2008) provided a
functional semantic classification of the size of extreme events (revised by Alexander
2016, p. ) and this might give us some basis for distinguishing phenomena by
the magnitude of their impacts.
Early classifications of disasters tended to dwell
upon the kinds of physical forces involved, and relate them to the geosphere,
biospehere, hydrosphere and atmosphere (Tank 1976). The gradual dissemination
of social studies prompted the addition of the noösphere (Vernadsky 1945). By
the 1990s, the emergence of civil protection from the matrix of civil defence
(Alexander 2002) had broadened the scope to the extent that there was a need
for a more functional set of categories. I suggest the following five:-
(a) Natural disasters, caused by extreme natural
events. Floods, storms and earthquakes dominate the picture, with the
ever-present possibility of very large eruptions or extra-terrestrial impacts.
(b) Technological disasters, caused by malfunction or
unintended consequences of technology. Included are toxic spills,
transportation crashes and the effects of human error.
(c) Social disasters, including crowd crushes, riots
and strikes among the providers of critical infrastructure.
(d) Intentional disasters, comprising all forms of
terrorism and sabotage.
(e) Compound and composite disasters, in which the
causes involve a mixture of any of the above. 'Na-techs' (natural-technological
disasters) appear in this category (Krausmann et al. 2019). Some other
indications of how categories (a) to (d) are linked are given in the following
figure.
There is currently a move to extirpate the term
'natural disasters' on the grounds that disasters by definition are not natural
events (UNDRR 2019, p. 165). This reflects a gradual distancing from the
concept of disasters as 'acts of God', which began in the mid-1800s and has
continued ever since. My viewpoint on this is that 'natural disasters' was only
ever used as a convenience term intended to distinguish phenomena with a
trigger in the natural environment from those with a technological origin
(Alexander 1993). A more up-to-date rationale might state that "there is
nothing more natural than human propensity to cause disasters."
It should be noted that sub-fields of disaster studies
may require their own classifications. For example, business continuity
management has a slightly different set of priorities which induces it to
change the emphasis among triggering factors (Elliott et al. 2010). The health
sciences also have a different perspective (Myrtle et al. 2005).
The next question is where to draw the boundaries in
the study of disasters and practice of disaster risk reduction. By convention,
conflict, warfare and disease epidemics are excluded. Pandemics are included
because many of the effects of a pandemic are likely to be socio-economic in
nature. There is also a link between pandemics and the 'intentional disaster'
of bioterrorism (Trufanov et al. 2010).
Currently, there is renewed interest in the
relationship between conflict and disasters, or, if the reader prefers,
conflict and other forms of disaster (e.g. Field 2018). Like disease outbreaks,
conflict is a disaster in its own
right. Why, then, do we not include it in disaster studies per se? The
principal answer is that we would be biting off more than we can chew. The need
to include military strategy and the strategic politics of defence in our
studies would unbalance them. Another reason is that disaster response has
undergone a long-drawn-out process of civilianisation. We do not wish to see it
dragged back into the military sphere. A third reason concerns the need in the
field to separate military (or "defence") missions from humanitarian
ones carried out by military forces. In conclusion, the military ethos is not a
suitable basis upon which to build modern disaster risk reduction, which is in
no sense a devaluation of the existence of military forces, but is instead an
observation on the separation of roles.
Other phenomena that lie outside the remit of those
who study disasters, but not far outside, are climate change and migration.
There is no doubt that climatic warming and species collapse are very special
kinds of disasters with long-term consequences that can scarcely be
contemplated. Warming has already begun to have a substantial effect on the
magnitude and frequency of meteorological hazards. Migration could conceivably
be the result of major disasters, not merely of climate trends (as they affect
the carrying capacity of areas of land) and of conflict, oppression and
political hostility. However, again, there is a need to draw a line and thus to
regard these as parallel or kindred phenomena, with which there is much
interchange, but they are not within the fold of disaster risk reduction sensu
stricto.
Finally, there is a very basic distinction between
disasters, which are events that tend to be concentrated in space and time, and
diffuse events such as road accidents. Paradoxically, there are countries, such
as Iran, in which the death toll on the roads is far higher than that in major
disasters. This should not be used as an excuse to reduce the priority of
disaster risk reduction, but it does not mean that DRR should include basic
quotidian road safety. The argument for not including minor accidents in
disaster studies is surprisingly weak. For example, work by Marulana et al.
(2010) showed that in Colombia the combined effect of 20,000 small destructive
events was much greater than the socio-economic impact of five large disasters.
Moreover, disasters such as drought can be neither concentrated in space nor
abrupt in time, and in this respect they bear some resemblance to small
accidents. However, spanning the continuum from major incidents to
catastrophes, disasters are discrete events and are not diffused throughout
society as are accidents. Of course, major accidents are disasters.
The following are some principles on which a taxonomy
of disasters could be based.
1. We classify disasters in order to deal with
"more manageable conceptual units."
2. Associating particular kinds of disaster with
classes of event obviates the need to restate basic information every time we
deal with such phenomena.
3. Classification focusses attention on the mechanism
that starts off the disaster. As part of a progression of thought and analysis,
attention can then proceed to the root causes and dynamic pressures.
4. In classifying disasters there is a distinction
between neutral forces, human error or negligence, and human malevolence. This
is useful to maintain and is inherent in the basis of the classification.
5. Disaster risk reduction policy is heavily
influenced by the class of disaster involved. For example, counter-terrorism
policy and policy against natural hazards can be quite different.
6. Taxonomy can start with basic distinctions
(natural, technological, social, intentional and composite) and then proceed to
further divisions and subdivisions.
Conflict, migration, minor accidents, epidemics,
general health conditions and climate change are thus outside the perimeter of
'disaster risk reduction'. This does not diminish their importance or the
strength of the links that they have with DRR. The rationale for excluding
phenomena from the disasters field may be weak on logic, but it is essential if
we are to give the field identity, cohesion and a firm theoretical basis.
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