Methods for Studying Impacts of ENSO
Introduction
El Niño and La Niña are notorious for being blamed for every
thing that has occurred during an event. Articles on El Niño often
have examples of this approach: a long list of all the bad things that El
Niño has done in the past. The list approach is not very useful if
our aim is to anticipate and respond to the impacts of future El Niño
and La Niña events. To be able to do this we need to have much more
information on:
- What is an ENSO impact, and what isn't?
- How consistently do the impacts occur during ENSO events?
- How and why do the impacts vary from one event to another?
The answer to the first question usually comes from knowing how ENSO affects
the climate conditions in the region where the impact occurred -- and whether
the impact is likely to have been caused by these climate conditions. To
find out more about the effects of ENSO on climate, see
Global effects of ENSO on climate.
The answer to the second question is important, because if there
is a consistent relationship, over a long period of time, between ENSO and
a particular impact, then we can be more confident that this relationship
will hold in the future. To identify and describe these relationships we
generally need to use statistical analysis of historical impact data.
The answer to the third question comes from looking in detail at what happened
during a particular ENSO event. It can give us a broad understanding of
the variety of ways in which climate affects society, the other factors
that contributed to the outcomes, and the usefulness of responses to forecasts.
This approach is usually descriptive rather than analytical.
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