Saturday, February 16, 2008

Hazards and Disasters

Classifying Hazards and Disasters:

There have been many recent efforts to classify hazards, the type of disasters they can cause, and to develop a typology which reflects the nature of the hazard, the level of risk they pose and what/who they pose a risk to.

While there are minor differences in these schemes, they are generally recognize similar categories of hazards: geologic, climatic or, more generally, natural vs. man-made (though the distinction is recognized as fuzzy) and so on.

They also recognize that hazards operate at different time scales, both in their onset or 'onslaught' and their duration as well as in their predictability and statistical frequency. Hurricanes come in seasons, though within the season they are still relatively unpredictable, volcanoes and earthquakes seem to follow long term statistical patterns but remain unpredictable on the short term (though volcanoes give definate and detectable warning signs).

UNEP (The United Nations Environment Program) published an excellent chart:

While this represents an excellent classification scheme for the most part, I propose several modifications. Firstly, the category "Climatic" should be "Meteorological/Climatic". Given the attention given to climate change, this is not an unnecessary distinction. Hazards such as storms, flooding, tornadoes, hurricanes and so on are current weather events- and meteorology is the study of such events, of current weather phenomenon. How current weather is going to change as a result of the increase in greenhouse gases (and concurrent global warming) is still largely unknown. While there is no doubt that global warming will produce changes in meteorological patterns over time (climate change)- and their is still great debate among scientists, climatologists, computer modellers and meteorologists about the exact nature of these changes- an excellent example is the ongoing debate regarding hurricane frequency and intensity.

Most scientists will agree that climate change is going to involve increased unpredictability of weather patterns and the possibility of increased intensity of some events such as hurricanes in the Atlantic for example, climate change may also be marked by diminishing intensity of other patterns (rainfall in given regions).

Typology of Hazards and Disasters: risk, vulnerability and complex causes

While until recently there was a tendency among scientists and others studying disasters to conflate the risk natural or man-made hazards with the risk of disaster. It is now generally recognized that the equation linking risk of a disaster to the frequency of a hazardous event is not a simple one.

It is important to distinguish between primary causes- the natural hazard, secondary causes- human activities and population patterns and so on and the actual disaster.
A food shortage or a famine, for example, can be caused by drought, flooding, storms or severe weather, and war and can be alleviated or compounded by social and economic organization and practices including international interventions. In the same manner a plague, epidemic or pandemic is not merely the result of a particular pathogen.

The important thing to remember is that the disaster is not the same thing as the hazard or other causes.

Primary Causes (Hazards)



flooding, drought, severe storms and related phenomenon (tornadoes, hurricanes, lightning)

Extraterrestrial (Impacts, Solar Flares, etc.)



The Environment and Poverty Times: Special Edition for the World Conference on Disaster Reduction January 18-22, 2005, Kobe, Japan. A publication of UNEP/GRID

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