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strategies involve forgoing potential advantage from positive climatic events to reduce the risk of disaster.

For most areas of the world, ex post strategies have limited value or are very costly. For example, U.S. citrus growers occasionally use grove heaters or, more frequently, spray trees with water to avoid the consequences of frost (Miller, 1988). African herders who experience adverse climate outcomes respond by migration, even making extraordinary movements under severe drought stress, including leaving the pastoral system until the perturbation passes (Coughenour et al., 1985; Ellis et al., 1987; Galvin, 1992).

Many of the ex ante production techniques listed in the table are common across many societies around the world. An example is hedging strategies to spread the risk of extremely negative climatic events. African pastoralists spatially separate their herds, and Indian farmers use diversified seed types and farm on multiple plots. Similarly, in the Great Plains of the United States, many farmers incorporate drought-resistant but low-profit grain sorghum with their drought-susceptible but highprofit corn-soybean rotations in anticipation of the adverse consequences of drought for their incomes. And both U.S. and African farm households are characterized by diversified occupational portfolios, with family members engaged in both agricultural and nonagricultural activities. The worldwide pervasiveness of such ex ante hedging strategies for both production and consumption suggests that the cost-effectiveness of ex post strategies is limited in most societies and that insurance—an alternative ex ante strategy—is either incomplete or more costly than the other ex ante strategies.

The size and distribution of the impacts of climatic variability depend strongly on the array of coping strategies available to and employed by agricultural producers. These in turn vary according to agroclimatic conditions and the structure of markets and other institutions. Groups facing the same climatic variability are more or less vulnerable to extreme negative climatic events depending on their ability to make use of particular coping strategies and methods. For example, low-income farmers in developing countries, who comprise a large proportion of the world population, are less able than their wealthier neighbors to accumulate assets while meeting minimum subsistence requirements; such poor farmers are thus less able to maintain their consumption by drawing from their savings levels when they experience particularly low levels of rainfall (Rosenzweig and Wolpin, 1993). Since many of these countries lack developed insurance markets, an inability to accumulate assets in anticipation of bad years makes poor farmers especially vulnerable. Because of their great vulnerability, the poor in less developed countries may benefit