Wilhite, D. A., and R. S. Pulwarty, 2005: Drought and water crises: Lessons learned and the road ahead. In Drought and Water Crises: Science, Technology, and Management Issues, D. A. Wilhite (Ed.), CRC Press, 389-398.
Despite the fact that drought is an inevitable feature of climate for nearly all climatic regimes, progress on drought preparedness has been extremely slow. Many nations now feel a growing sense of urgency to move forward with a more proactive, risk-based drought management approach (ISDR, 2003; Wilhite, 2000). Certainly the widespread occurrence of this insidious natural hazard in recent years has contributed to the sense of urgency. But, drought occurs in many parts of the world and affects portions of many countries on an annual basis. For example, the average area affected by severe and extreme drought in the United States each year is 14%. This figure has been as high as 65% (1934) and has hovered in the 35-40% range in recent years. So, does the widespread occurrence of drought in the United States over the last 5-6 years explain the emergence of several national initiatives centered on drought monitoring and preparedness, given that events of this magnitude have not motivated policy makers to act in the past? Our experience would suggest that this is only one of the factors contributing to the increased attention being directed to this subject in the United States and in other drought-prone countries.
Climate change and the potential threat of an increase in frequency and severity of extreme events are also a contributing factor. However, the uncertainty associated with climate change is probably not playing a significant role in this trend because most policy makers have difficulty thinking beyond their term of office or the next election. For regions that have in recent decades experienced either a downward trend of annual precipitation of a higher frequency of drought events (perhaps multi-year in length), or both, the potential threat of climate change already seems real. Decision making under uncertainty is onerous, but critically important. Policy makers and resource managers often seem of the opinion that climate change projections are in error, preferring to presume that there will not be a change in the climate state and that extreme climatic events such as drought will not change in frequency or severity. Little consideration is given to the real possibility fact that projected changes in climate may be too conservative or underestimate the degree of change in the frequency and severity of extreme events for some locations.
In our view, the most significant factor explaining the growing interest in drought preparedness is associated with the documented increase in social and economic vulnerability as exemplified by the increase in the magnitude and complexity of impacts. Although global figures for the trends in economic losses associated with drought do not exist, a recent report from the U.N. Development Program (UNDP Bureau of Crisis Prevention and Recovery, 2004) indicates that annual losses associated with natural disasters increased from US$75.5 billion in the 1960s to nearly US$660 billion in the 1990s. Losses resulting from drought likely follow a similar trend. In addition, these figures for natural disasters are likely underestimated because of the inexact reporting or insufficiency of the data. And, these loss estimates do not include social and environmental costs associated with natural disasters over time. This increase has been observed in both developing and developed countries, although the types of impacts differ markedly in most cases, as illustrated by numerous authors in this book.
With respect to drought, how can we define vulnerability? It is usually expressed in terms of a society's capacity to anticipate, cope with, resist or adapt to, and recover from the impact of a natural hazard. Vulnerability is represented by a continuum from low to high and varies among community, population group, region, state, and nation. It is the result of many social factors. For example, population is not only increasing by also shifting from humid to more arid climates in some areas and from rural to urban settings for most locations. As population increases and lifestyles change, so do the pressures on water and other natural resources. Conflicts between water users escalate accordingly. Population increases force more people ot reside in climatically marginal areas where exposure to drought is higher and the capacity to recover is diminished. Urbanization is placing more pressure on limited water supplies and overwhelming the capacity of water supply systems to deliver that water to users, especially during periods of peak demand. An increasingly urbanized population is also increasing conflict between agricultural and urban water users, a trend that will only be exacerbated in the future. More sophisticated technology decreases our vulnerability to drought in some instances while increasing it in others. Greater awareness of our environment and the need to preserve and restore environmental quality is placing increased pressure on all of us to be better stewards of our physical and biological resources. Environmental degradation such as desertification is reducing the biological productivity of many landscapes and increasing vulnerability to drought events. All of these factors emphasize that our vulnerability to drought is dynamic and must be evaluated periodically. The recurrence of drought today of equal or similar magnitude to one experienced several decades ago will likely result in far greater economic, social, and environmental losses and conflicts between water users.