Human need is central to sustainable development as defined by the Brundtland Report: sustainable development is development that meets the needs of current generations without compromising the ability of future generations to meet their own needs (WCED, 1987). But the concept of human needs is controversial. The word need is used in many ways: as a strongly felt lack or want; as a positive motivation or desire; and as a necessary condition for something, such as survival, social acceptance, or health. The failure to distinguish these different meanings has confused efforts to agree on the morality of need-fulfilment (Michaelis, 2000b).
One major barrier to the success of many policies is the failure to take account of the full range of human motivations and goals. For example, an engineer may design an energy-efficient building that provides occupants with adequate shelter and warmth, but it may be hard to get people to live in it if it is in the wrong area, or lacks features normally associated with adequate social status. Similarly, public transport may provide fast, efficient mobility for certain trips, but young men may see car ownership as the only way to attract a girlfriend. Maslow (1954) explained motivation in terms of human needs, which he divided into categories: physiological needs, sense of belonging, esteem, and self-actualization. He saw these categories as a hierarchy, arguing for example that we are only concerned about self-esteem when we have had enough to eat. While the idea of a hierarchy has been largely discredited (Douglas et al., 1998), Maslows categorization of needs continues to be widely used. Max-Neef (1991) proposed a more complex categorization of needs, divided into having, doing, being, and relating needs, and emphasized the distinction between needs and satisfiers.
While some consumption may respond to perceived needs, much is habitual. Habit formation is an important barrier to GHG mitigation as consumers may be unwilling or unable to change their behaviour or technology choices. The continuation of rising consumption levels has been widely observed and was noted by Jean-Jacques Rousseau in 1755 (Schor, 1998; Wilk, 1999). What was once luxury rapidly becomes habit, and then need. This is partly a social, as opposed to an individual psychological phenomenon, and will be discussed further in the next section. Often, we may try to use inappropriate satisfiers to meet particular needs (Max-Neef, 1991) for example, eating in response to feelings of loneliness. Consumption of such ineffective satisfiers can become compulsive, especially when they give a short-term feeling of relief but fail to satisfy in the long term.
There may be opportunities for GHG mitigation in identifying where low-GHG-emitting behaviour can help to meet needs better than existing behaviour. Argyle (1987) finds from a review of several studies that human happiness is influenced mainly by health, the quality of family life, marriage, and friendships. Having meaningful work is also important. Absolute levels of material wealth are relatively unimportant: many studies have found that, once basic material and healthcare needs are met, happiness is largely independent of absolute income levels (Jackson and Marks, 1999; Inglehart, 2000), although relative income remains important as an indicator of social status. Efforts to promote low-GHG consumption patterns such as domestic energy conservation, cycling rather than relying on a car, living in higher density housing, or eating less meat might have the most success if they emphasize ancillary benefits in terms of improving health, family life, and community relationships rather than saving money.
Sen (1980, 1993) has developed a concept, related to human need, of the capabilities that individuals must have if they are to flourish or to live a good life. Individuals require different capabilities depending on their personal circumstances and the community they live in. While the good life is to some extent subjective, it is also socially defined. Some aspects of energy-using behaviour may be very hard to change because they play important roles in culture-specific ideals of the good life, varying from country to country. Wilhite et al., (1996) describe the cultural significance of lighting and heating in Norway, and of bathing in Japan, suggesting that energy saving measures in these areas would need to be very sensitive to cultural requirements. They also observe that other aspects of household behaviour, such as washing clothes, are less culturally significant and may be easier to change. International differences in habitual behaviour in such areas might provide opportunities for encouraging change through information and education programmes emphasizing best practice.
Moisander (1998) describes how motivation is shaped by both broad values and attitudes, and by more specific priorities, and also how the ability to act depends on both personal capabilities or resources, and external factors or opportunities. Surveys of public attitudes in the United States find an increasing level of concern about climate change, and agreement that action is needed to save energy and protect the environment (Kempton et al., 1992; Kempton, 1997). One of the challenges for individuals in acting on environmental values and attitudes is the need to reconcile divergent objectives. This is all the more difficult in the case of climate change, which is poorly understood by most people (Kempton, 1991, 1997; Lofstedt, 1992; Wilhite et al., 1996). Moisander (1998) finds that being concerned about the environment provides some motivation for environmentally friendly behaviour. But identity (as a green consumer) and internalized moral ideals or imperatives play a much stronger role. Identity and ethics, which play an important role in shaping consumption patterns, are largely social phenomena and will be discussed in more detail in the next two sections.
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