Understanding vulnerability

Vulnerability represents the interface between exposure to the physical threats to human well-being and the capacity of people and communities to cope with those threats. Threats may arise from a combination of social and physical processes. Human vulnerability thus integrates many environmental concerns. Since everyone is vulnerable to environmental threats, in some way, the issue cuts across rich and poor, urban and rural, North and South, and may undermine the entire sustainable development process in developing countries. Reducing vulnerability requires identifying points of intervention in the causal chain between the emergence of a hazard and the human consequences (Clark and others 1998).

Many natural phenomena pose threats, including extreme events such as floods, drought, fire, storms, tsunami, landslides, volcanic eruptions, earthquakes and insect swarms. Human activities have added to the list, with threats from explosions, chemical and radioactive contamination, and other technological incidents. The risk lies in the probability of exposure to any of these events, which can occur with varying severity at different geographical scales, suddenly and unexpectedly or gradually and predictably, and to the degree of exposure. With an increasing and more widely distributed global population, however, natural disasters are resulting in increasing damage, loss of life and displacement of populations. In addition, human-induced changes to the environment have reduced its capacity to absorb the impacts of change and to deliver the goods and services to satisfy human needs.

The analysis of environmental impacts in Chapter 2 revealed many examples of where individuals, communities and even countries are vulnerable to threats from their physical environment. Environmental change and social vulnerability to it is nothing new. More than 9 000 years ago, the Sumerians of Mesopotamia started irrigating land to meet increased demand for food from a growing population but their civilization eventually collapsed partly because of the waterlogging and salinization that resulted. The Mayan civilization collapsed around 900 B.C. mainly as a result of soil erosion, loss of agro-ecosystem viability and silting of rivers. The Dust Bowl phenomenon of the American prairies in the 20th century resulted from massive soil erosion, and led to communities being uprooted and widespread poverty. During the three days of London's 'Great Smog' of 1952, some 4 000 people died as a result of a lethal combination of air laden with particulates and SO₂ from the widespread burning of coal and a temperature inversion caused by anticyclonic conditions over the city (Met Office 2002).

Some people live in places of inherent risk to humans - areas, for example, that are too hot, too dry or too prone to natural hazards. Others such as Rosita Pedro are at risk because an existing threat has become more severe or extensive through time. Places or conditions which were once safe have been so altered that they no longer safeguard human health and well-being adequately. Many of the children under the age of five who die every year from diarrhoeal disease contract it from drinking contaminated water (see Chapter 2, 'Freshwater').

Most environments are in a constant state of flux because of natural causes and human modifications for food production, settlements, infrastructure, or to produce and trade goods. Most intentional changes are designed to harness the environment for human benefit. Domestication of land for intensive food production is one example; harnessing river resources to provide fresh water, energy and transport is another. Such changes may also unintentionally alter the quality or quantity of environmental resources and be difficult to cope with.

Analysing old and new threats to human security shows that human vulnerability to environmental conditions has social, economic and ecological dimensions. The most conspicuous and widely reported manifestation of this vulnerability is when people are affected suddenly and violently by natural hazards such as the eruption of Mount Nyiragongo resulting in the devastation of the town of Goma in the Democratic Republic of Congo (see box). These events turn into disasters when local communities are not able to cope with their impacts. The environmental factors that contribute to human vulnerability, however, are both varied and variable, and are not limited to disaster events; they span the whole sustainable development spectrum.