Chris de Freitas: Nature not only culprit in disasters

Chris De Freitas

Knowledge of the past is an important ingredient of any recipe for accurately predicting the future. But based on recent experiences, you would not think so.

Whether it be the Marlborough drought seven years ago, the Manawatu flood last February, or the New Orleans tragedy this month, reactions to natural disasters reveal curious perspectives on natural hazards that prevail among politicians and the public.

It is based, at least in part, by a poor understanding of why natural disasters occur. It is not simply natural events that cause them. They are mainly a product of social, political and economic behaviour. In fact, most natural disasters are not what the label implies. They are a mix of nature and human action.

Take Hurricane Katrina, for example, an entirely normal and predictable weather event that affected a city built on a swamp in a bowl of land below the level of the nearby sea and river, which lies within the standard track of many hurricanes that originate in the Caribbean and Gulf of Mexico.

UK geographer Philip Stott points out that Hurricane Katrina was not even a particularly strong or unusual hurricane, varying between 2-4 on the Saffir-Simpson Scale. The most recent peak in hurricane activity still lies within the late-1930s and 1940s.

In 1965, New Orleans was struck by Hurricane Betsy that flooded the city and killed more than 70 people.

Nothing that cannot be attributed to natural variability is happening. In power, Katrina was no match for the category 5 hurricane Camille, with winds of over 320km/h, which hit Louisiana, Alabama, and Mississippi in August 1969, killing some 275 people.

Stott makes the point that, in the future, we know more hurricanes will affect the settlements along the Gulf of Mexico coastline, although the precise timing, direction, and strength of them cannot be known in advance.

"The only human culpability in the current tragedy is the failure to recognise the inevitability of this natural reality and to exercise enough effort and money to plan landscapes that can cope with the predictable risk," he says.

For another example closer to home, take Australia's devastating drought that abated less than three years ago. Australia's corporate elite, headed by its richest man, Kerry Packer, formed a multimillion-dollar alliance, the Farmland Foundation that, with state and federal Governments, aimed to rescue drought-stricken farmers. The fund-raising campaign highlighted a widespread misunderstanding of climate resources and the use of climate information in business decision-making.
For a start, there is a rule of thumb that says the lower the average annual rainfall of a region the higher the variability. Thus, the occurrence of drought in large parts of Australia should not be in the least surprising, nor should it be when it occurs next in the drier areas of New Zealand, such as Hawkes Bay, Nelson/Marlborough and Central Otago. Droughts should be considered a standard feature of these regions' climates. And as agriculture expands into the poorer land areas, worse can be expected.

The decision to live in a tropical cyclone-prone, drought-prone or flood prone area is voluntary. As a result of prior events, the places affected are generally known. Clearly, a lack of rain is implicated in causing a drought disaster, or an excess of it in case of floods. But vulnerability to these is generated, say, by building or farming on flood-prone or drought-prone land. On the other hand, areas at risk from flooding often offer considerable commercial benefits for farming, such as fertile alluvial flood plains or cheap-to-buy dry lands; or commercial rewards for developing scenic coastal land.

The results of research into how to "drought-proof" an area shows the best planning advice to land users is: adapt to the perceived risks. Where the risk is clearly high people could be guided towards adopting appropriate land use practices; for example, replacing buildings with parks on flood prone land, or using dry-farming methods to cope with droughts. An alternative is bear the costs of droughts or floods, which may include paying exorbitantly high insurance premiums, or opting for no insurance at all in the hope relief money from local or central government or directly from the public would be forthcoming.

In the case of New Orleans, a more drastic but perhaps more sensible alternative would be to cease operating in high-risk zones.

For businesses on flood-prone land to expect to receive relief-money as compensation for damage is no different to houseowners on a flood plain of a river demanding compensation from government when the inevitable flood occurs.

Relief aid generally works to ensure the same people and areas will be affected again, since it discourages taking action to avoid, reduce or mitigate future occurrences. In addition, the expectation of bailouts distorts the true climate resource potential of a region. What is an unacceptable risk in one place where there is no chance of a government or other relief in time of drought may turn out to be quite an acceptable risk at the same place where there is an expectation of financial bailout or national or regional compensation packages. The bottom line is costs and benefits of mitigation measures need to be carefully considered.

Decision-makers in our society perceive climate as a backdrop to life, usually described as an array of means, normals or probabilities of occurrence. These statistics rely on the availability of an instrument record of past climate.

One can recall the squeals of despair coming from the Queenstown City Council less than two years ago over the difficulty central city businesses were having obtaining flood insurance following the one in a 300-year flood that devastated the CBD in 1999.

Their concern highlights the curious perception many New Zealanders have of their climate. The instrument record of climate is seldom more than about 100 years.
In terms of identifying patterns of natural processes, this is a minute fragment of time.

Using it as a reference is like composing an annual budget based on one Saturday's expenses. Besides, return period probabilities of floods and droughts are estimates, not facts. For example, it is false to assume that a 100-year flood will occur or be exceeded every 100 years. In fact, there is a high (63 per cent) probability of a 100-year flood occurring more than once in a given 100-year period.

Moreover, there is a small but significant likelihood that two or more floods more serious than a 100-year flood will occur in a given 20-year period.

An example of this is the two major floods that occurred in Greymouth during 1988, where a 13-year and a 36-year flood occurred in the same year.

Clearly, there are lessons to be learned from past experience. They point to a number of practical and policy measures than can be promoted to manage risk and reduce costs.

Otherwise, as population, value and aerial extent of developed land increase, the cost of natural disasters will continue to grow.

* Chris de Freitas is an associate professor in the School of Geography and Environmental Science at the University of Auckland.