ESIG Alert #6, February 2004


Early warning systems (EWSs) have evolved considerably during the past two decades. They gained attention in the 1970s and 1980s during the extended droughts and famines in the West African Sahel and in the Horn of Africa. Famine EWSs were created in at-risk countries and regions in sub-Saharan Africa in donor countries and international organizations, primarily for humanitarian purposes. Today, formal EWSs exist for just about every hazard - technological, hydrological, meteorological, and anthropogenic. They have also been created for conflict, ecological changes, health-related and complex humanitarian crises. Their functions have shifted toward societal risk and vulnerability reduction and toward sustainable development.

An early warning system is an important tool in a government's toolbox for achieving sustainable development. It can be used to encourage settlements to develop in relatively secure areas. It is, in a way, analogous to a flashlight that can be used to illuminate obstacles along the path of development. A hydrometeorological hazard may take but a few hours, days, or weeks to occur, but its adverse consequences can derail development efforts for years to come. An effective EWS can help individuals as well as societies to deal with potential disasters and aid the process of sustainable development.
Interest in early warning of all kinds of traditional, natural, and anthropogenic hazards has increased markedly over the past few years, as new hazards arise and known hazards appear in new places, including global warming, solar wind storms, rare virus outbreaks, mutating forms of global terrorism, and so on. Societies must remain alert, and early warning systems provide them with one way to remain vigilant, more so now than ever before.

Most people probably envision an early warning system as including a formal bureaucratic structure, with organizational charts showing who reports to whom. However, in many societies there are uncharted patterns of human interactions that fulfill the functions of EWSs. Those systems have been learned over time, through generations, in order to cope with certain hazards.

A universally accepted definition of an early warning system does not yet exist and most probably never will. It is necessary to keep a general definition of an EWS broad enough to allow for a wide range of interpretations and flexible enough to accommodate the recognition of new hazards and the development of new technologies. Many definitions are used to guide the actions of individuals, groups, and governments. Several honest scientific disagreements exist, such as about what an EWS should do for a government, society, corporation, or an individual. Even with a highly effective early warning, it is reasonable to expect that problems will still arise in the affected region, so lessons learned from past experiences should remain of interest in any EWS.

A workshop was organized in October 2003 in Shanghai, China by Michael Glantz of ESIG and Zhang Renhe of the Chinese Academy of Meteorological Sciences (CAMS) to look at early warning systems to alert at-risk people, communities, and governments about the possible onset and impacts of hydrometeorological and other hazards.

Participants addressed the success and limitations of early warning systems and identified lessons - do's and don'ts - from the experiences of those who have worked with or helped to develop EWSs for a wide range of societal concerns. It is hoped that the lessons, experiences, and insights identified at the workshop will be used to remind, if not inform, government officials as well as decision-makers in various government agencies about how to make early warnings of potential hazards, especially hydro-meteorological hazards, effective.

For purposes of illustration, society can be graphically represented by a pyramid, the base of which represents sustainable development. The apex of the pyramid represents an early warning sentinel. Its function is to protect society from harm due to natural hazards. This suggests that EWSs have the role of identifying potential problems for a government as it seeks to pursue environmentally and economically sound development strategies. However, one might suggest that in reality one could view this in the opposite way: with the pyramid resting on its apex and not on its base. The point is that sustainable development prospects of a society are very dependent on the effectiveness of its various early warning systems.

Hazards are known to have the potential to set back economic development progress for long periods of time because of the need to divert funds away from development to emergency, disaster, and reconstruction activities. The society must rebuild the affected regions just to get it back to "normal." Thus, sustainable development prospects, and even the stability of a government, are much more dependent on successful early warnings than most observers and governments realize.

Early Warning Lessons

Many lessons have been learned with respect to the operations of various kinds of EWSs, their warnings, and the impacts of warnings and hazards. However, those lessons have not always been applied to prepare for similar hazards in the future. Lessons learned as a result of disasters come at a high cost: death, destruction, and misery. The survivors are the beneficiaries of those lessons, but only if those lessons are actually used.

There are many reasons that lessons identified as a result of one hazard are not used when seeking to cope with similar hazards in the future. For example, the value of many lessons may be discounted because society believes that progress (technological, economic, and social) has rendered those lessons irrelevant. Lessons identified in the past may also be viewed as having limited value because society's level of vulnerability may have changed over time, causing those lessons to appear less meaningful.

Even a political aspect is present, in that democratic as well as other kinds of changes in government can lead a new government administration to neglect or rescind the useful hazard-related activities established by the preceding government. Some governments might not want lessons to be identified and then exposed to the public, because such lessons can expose governmental weaknesses as well as strengths.

There is a tendency for a government or a society to focus on and respond to the last disaster instead of taking a broader view. As a result, it tends to pursue policies that look back, as opposed to those that might be forward-looking and anticipatory of variations in impacts that might accompany future potential harm.

At the least, whether focused on one hazard or on complex humanitarian crises encompassing several hazards simultaneously, the following five Ws must be addressed. They can be used to educate the public about EWSs: what, when, where, who, and why. What is happening with respect to the hazard(s) of concern? When is it likely to impact (providing as much usable lead time as possible to at-risk populations)? The time to educate the public and policy makers about an EWS's strengths and weaknesses is between episodes and not during them. Where are the regions most at risk? While a flood event, for example, might directly affect only a small part of a watershed, it is essential for early warning purposes to look for incremental changes in the larger watershed and river basin, since land-use activities can affect the likelihood of flooding. Who are the people most at risk, i.e., who needs to be warned? People who live in regions at risk to various hazards need to be educated about early warnings and what they can and cannot provide. Why is this a threat in the first place, i.e., what are the underlying causes of potential adverse impacts?

In August 2003, a heat wave blanketed Europe and more than 15,000 mostly elderly people died in France alone. Why and how did the system fail to protect citizens?

An early warning of a hazard usually sets in motion a cascade of other EWSs related to anticipated second-order effects as the hazard's impacts ripple through society. The heat wave in Europe was forecast accurately by various national meteorological services, but apparently no cascade of downstream early warnings was set into motion. The event illustrates the need to improve the coordination among a wide variety of early warnings.

For the full workshop report, findings, and recommendations, see the website at To receive hard copies or send comments, write to or

Participants at the Usable Science 8: Early Warning Systems Do's and Don'ts conference held in Shanghai, China, on 20-23 October 2003.

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The National Center for Atmospheric Research (NCAR) is sponsored by the National Science Foundation.