. Investment Purchases of manufacturing equipment and consumer durables are ''built in'' for a decade or two; investments in buildings, roads, and water supply systems may last centuries.
. Socialization Intergenerational learning, by definition, takes decades to change. Environmentally relevant attitudes may be shaped mainly by personal experience or by socialization from the previous generation, with different consequences for the maximum rate of change of such attitudes in a population.
. Major global social transformations The rise and spread of capitalism, the industrial revolution, the decline of the European peasantry, the development and transformation of the nation-state system, the settlement and development of frontiers, and the creation of a global market all occur on the time scale of centuries (Cronon, 1983; Polanyi, 1944; Wallerstein, 1974, 1980, 1988; Wolf, 1982). Many of them are closely correlated with anthropogenic global change, and some are probably causative.
. International regimes Patterns of formal and informal practice among nations evolve on the time scale of decades or more, and some are relevant to environmental management (e.g., Wallerstein, 1974, 1980, 1988; Cox, 1987). Examples include the emerging international norm that makes states responsible for environmental protection; the development of international organizations, such as the International Atomic Energy Agency; and changing practice at the World Bank with respect to environment and development.
. Family and labor force structure Changes in household size, female labor force participation, and educational levels of adult populations occur over several decades (Ryder, 1965; Lindert, 1978). Such changes can indirectly affect the global environment through impacts on economic development, energy demand, and population growth rates.
. Diffusion of innovation Change in technology for manufacturing, commercial, or consumer use; practices in agriculture, commerce, or government regulation; and the design of social and political institutions normally takes a few decades or more (e.g., Sahal, 1981; Ausubel, 1989). The social time lag between the development of innovations that can affect the global environment and their implementation depends on conditions not yet well understood.
. National social transformations Even revolutionary changes, such as the ascendancy of market economic principles in Poland and Hungary in 1989 or the Reagan deregulation policies in the United States in 1981, often take decades for their full effects on the environment to appear because of resistance to implementa-