Extreme weather events, and climatic anomalies, have major impacts on agriculture. Of the total annual crop losses in world agriculture, many are due to direct weather and climatic effects such as drought, flash floods, untimely rains, frost, hail, and storms. High preparedness, prior knowledge of the timing and magnitude of weather events and climatic anomalies and effective recovery plans will do much to reduce their impact on production levels, on land resources and on other assets such as structures and infrastructure and natural ecosystems that are integral to agricultural operations. Aspects of crop and livestock production, as well as agriculture's natural resource base, that are influenced by weather and climatic conditions include air and water pollution; soil erosion from wind or water; the incidence and effects of drought; crop growth; animal production; the incidence and extent of pests and diseases; the incidence, frequency, and extent of frost; the dangers of forest and bush fires; losses during storage and transport; and the safety and effectiveness of all on-farm operations (Mavi and Tupper 2004).

Figure 1.1 illustrates how the climate influences agricultural production - specific climatic conditions, including absence of extremes, are required for optimum production, ttere are major gaps between the actual and attainable yields of crops, largely attributable to the pests, diseases and weeds, as well as to losses in harvest and storage.

When user-focused weather and climate information are readily available, and used wisely by farmers and others in the agriculture sector, losses resulting from adverse weather and climatic conditions can be minimized, thereby improving the yield and quality of agricultural products. While most emphasis should be placed on preparedness and timely management interventions, there will always be a need for the capacity to recover quickly and minimize the residual damages of adverse events and conditions (Stigter et al. 2003).

ttis paper focuses on a risk-based approach to managing the detrimental consequences of extreme weather events and climatic anomalies such as those described above. Basic concepts related to risk and to risk management are explained, followed by a discussion of farming risks. Details of risk characterization procedures are provided, along with some practical examples. Given the important consequences of climate change for agriculture, attention is given to projection of risk levels into the future. Again some practical examples are provided. Finally, relevant aspects of risk management are discussed. Overall conclusions are also presented.

3 Pasture j] production

Horitcullura fiber production

Grain, oilseed, arid

Livestock production vegetable production

Fig.1.1. ^erole of climate in agricultural production (from Mavi and Tupper 2004).

Why a risk-based approach? In recent decades there have been major advances in short-term and seasonal weather forecasting, as well as in long-term climate modelling, ttese have yielded major improvements in early warnings and advisories as well as in longer-term planning, ttis is resulting in increasing emphasis on proactive rather than reactive management of the adverse consequences of extreme weather events and anomalous climatic conditions on agriculture. It is also increasing the diversity of options available to farmers and others in the agriculture sector to manage those impacts. Increasingly, farm managers and other practitioners are seeking more rational and quantitative guidance for decision making, including cost benefit analyses. As will be demonstrated in the following sections, a risk-based approach to managing the adverse consequences of weather extremes and climate anomalies for agriculture goes a long way towards meeting these requirements. It also provides a direct functional link between, on the one hand, assessing exposure to the adverse consequences of extreme weather and anomalous climatic conditions and, on the other, the identification, prioritization and retrospective evaluation of management interventions designed to reduce anticipated consequences to tolerable levels.

Finally, risk assessment and management procedures have already been embraced by many sectors in addition to agriculture - e.g. health, financial, transport, energy, and water resources. As will be shown in the following section, a risk-based approach provides a common framework that facilitates coordination and cooper ation amongst various players and stakeholders, including the sharing of information that might otherwise be retained by information "gate keepers".

Risk and Risk Management - Some Basic Concepts

Risk considers not only the potential level of harm arising from an event or condition, but also the likelihood that such harm will occur. In the present context, risk events include weather-related hazards such as extreme daily rainfall and frost. Risk conditions are climate-related and include hazards such as droughts and heat waves. Risk levels can change, including as a result of potentially detrimental changes in the climate (e.g. warming, decreasing rainfall). Changes in levels of exposure, due to altering levels of investment, can also influence risk levels. As defined above, risk combines both the likelihood of a harm occurring and the consequences of it doing so. ^us, in risk terms, an unlikely hazard or condition causing considerable harm (e.g. a category 5 hurricane, such the cyclone in the state of Orissa that devastated parts of India in 1999), may be compared to a hazard or condition which causes less harm but has a higher probability of occurring (e.g. a seasonal drought). By way of illustration, Figure 1.2 shows the likelihood of given extreme daily rainfall amounts for Delhi, India. A relatively common daily rainfall of, say, 30 mm will obviously result in far less devastation than the maximum observed daily rainfall of 192 mm.

Fig. 1.2. Probability of a daily rainfall (mm) in 25 mm bands up to the given amount. Based on 1969 to 2004 data for Delhi, India. Data courtesy oflndia Meteorological Department.Ebunte

Harm may be expressed in many ways, such as loss of production in tonnes or number of livestock fatalities. Where the harm can be due to several different causes, use of the same units to describe the harm makes it possible to combine the different categories of risk, tte result is the total risk, ttus:

Total risk = Z; (Likelihoodi * Harmi)

ttere is a well established approach to characterizing and managing risks (Figure 1.3). As noted above, the risk-based methodology makes explicit the link between weather- and climate-related risks and the actions required to reduce them to acceptable levels, tte widely-used procedures for characterizing and managing risk provide the basis for procedures which relate more specifically to characterizing and managing weather- and climate-related risks of relevance to the agriculture sector (Figure 1.4).

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