Early Warning Systems Defined - Reducing Disaster: Early Warning Systems for Climate Change - page 86

5.1 What Is an EWS?

5.1.1 EWS in General

A universally accepted defi nition of an early warning system (EWS) does not exist
and probably never will exist.

Box 5.1 EWS Defi nitions—And Lack Thereof!

The United Nations International Strategy for Disaster Reduction (UNISDR
2012 : online) defi nes an early warning system to be 'The set of capacities
needed to generate and disseminate timely and meaningful warning informa-
tion to enable individuals, communities and organizations threatened by a
hazard to prepare and to act appropriately and in suffi cient time to reduce the
possibility of harm or loss'. Interestingly, The United Nations Department of
Humanitarian Affairs (DHA 1992 ) defi nes 'warning' but neither 'warning
system' nor 'early warning system'.

As implied by UNISDR's ( 2012 ) defi nition, a fundamental part of an EWS
generally accepted by most disaster risk reduction (DRR) literature (e.g. Gruntfest
et al. 1978 ; Lewis 1999 ; Wisner et al. 2004 , 2012 ) is that EWS is a social process
aiming to address the need to avoid harm due to hazards. The social process occurs
at a variety of spatial scales, from individuals in isolated villages without electricity
through to the global UN processes working with governments.
Emphasising the social process contrasts with technical views that an EWS com-
prises only the technical equipment detecting a hazard event and sending the hazard
parameters to authorities for decision-making. Instead, the 'system' of the EWS
needs to include the decision-making authorities and their decision-making pro-
cesses, along with many other social aspects before and after a hazard event occurs.
EWS as a social process embraces, rather than precludes, the technical aspect—
but the technical aspect is always placed in its social contexts. The technology might
be chains strung across a river which create noise when the river reaches a certain
height, alerting people. The technology might be the sophisticated international sys-
tems of seismographs and buoys telemetering real-time data of earthquakes and
tsunamis to monitoring stations.
The onset time of the hazard is one input into the level of technical expertise
required within an EWS, although some research suggests that too much lead time
can lead to potentially dangerous behaviour (Hoekstra et al. 2011 ). For instance,
tornado warnings generally give minutes of lead time for a warn-on-detection system