effects of climate variability on weather-dependent sectors of human life and indicates the general state of knowledge about them.
Agriculture, including both plant cultivation and livestock production, is a sector that is heavily dependent on the amount and timing of rainfall, which in many areas of the world are highly variable. For example, the dry rangelands of Africa, which receive less than 600mm of rain per year, experience some of the greatest climatic variability on the continent. El Niño/Southern Oscillation (ENSO) events have caused droughts in southern Africa with a frequency of three to six years since the 1950s (Trenberth and Shea, 1987; Scoones, 1992). In the semiarid tropical zone of India, cultivation must wait for the onset of monsoon rains because of the hardness of the soil, and the timing of the monsoon onset is highly variable. Some agricultural systems are also highly sensitive to climate parameters other than rainfall, such as the occurrence of killing frosts, the length of the growing season, and the number of growing degree-days.
In all areas of the world and at all levels of economic development, human cultures inhabiting variable environments have developed strategies and behaviors designed specifically to ameliorate the effects of climatic variability on their subsistence (Galvin, 1992; Halstead and O'Shea, 1989). Indeed, in a variety of cultures and environments that exist under the stress of high climatic variability, primary cultural characteristics such as social relations, land tenure systems, institutions, laws, and land use practices are organized as coping mechanisms for dealing with climatic variability (Minc and Smith, 1989; Legge, 1989; Blaikie and Brookfield, 1987; Halstead and O'Shea, 1989; Fratkin et al., 1994).
The methods by which individuals directly engaged in agricultural production cope with climatic variability can be classified according to whether these strategies and behaviors affect production (the sensitivity of agricultural output and incomes to climatic events) or consumption (the ability of agriculturists to acquire food and other goods and services in spite of climate-related fluctuations in their agricultural production). Coping mechanisms can also be classified by the timing of the actions relative to the occurrence of the climate event. Actions taken prior to the realization of a particular climate event, such as the onset of the monsoon or unusually heavy rainfall (ex ante or risk management actions), are based on expectations of the likelihood of bad or good events, which are in turn based on primarily historical experience. Activities that take place after the event has occurred (ex post) attempt to ameliorate or exploit what has already occurred.