ENSO and the Americas

The El Niño-Southern Oscillation (ENSO) phenomenon was the subject of a scientific workshop held in July 1994 in Lima, Peru. Over 70 people from the Americas attended the workshop, organized by the Inter-American Institute for Global Change Research (IAI).

The aim of the Lima workshop was to coordinate activities involved with the documentation and prediction of interannual climate variability in the Americas and to outline plans for the identification and the assessment needs of potential climate forecast users.

The workshop suggested an agenda for inter-American study and cooperation that might lead to the successful application of forecasts of ENSO-related climate variability. Research activities are being developed concerning other regional processes that contribute to interannual climate variability, including land-surface processes.

One of the key points made at the outset of the workshop was that, although knowledge about ENSO processes has increased rapidly in recent years, forecasting of El Niño events remains in the early stages of development. Yet the benefits to be gained from accurate forecasts are considerable.

The ability of societies to adapt to climate has determined survivability since the beginning of time. Seasonal changes in climate in a particular region are generally understood by the people living there. But dramatic shifts away from expected patterns can cause extreme physical and economic hardship.

Because extended periods of warmer water affect fish populations, the ENSO of 1972-73 contributed to the collapse of the Peruvian anchoveta fishing industry which, by tonnage, had made Peru the number one fishing nation in the world.

The ENSO of 1982-83, believed the most severe of this century, caused losses in several countries estimated at more than 13 billion US dollars and some two thousand deaths.

Northeastern Brazil, home to more than 20 million people, is often severely affected by droughts, while southern Brazil experiences damaging floods. ENSO events appear to play a part in these anomalies. Floods also impact Paraguay, Uruguay and northern Argentina during an ENSO event, as do flash floods in the coastal plains region of northern Peru and southern Ecuador. Anomalously wet conditions are typical along the subtropical west coast (central Chile) during the austral winter.

Contrasting with these climate anomalies, droughts tend to occur in northern South America and in the Altiplano region during major ENSO episodes. Precipitation and temperature also drive mosquito production, so ENSO-related variability can cause increases in diseases such as dengue fever, yellow fever and malaria. Drought removes some of the predators of rodents, causing not only an increase of rodent-driven diseases but increased damage to cereal crops.

Understanding and recognizing the mechanisms that lead up to an ENSO event could aid in the prediction of such occurrences, thereby alleviating much suffering and economic hardship.

By applying updated information related to climate variability and its effects, governments can advise their citizens of upcoming climatic changes, and industries can prepare for possible variations in precipitation and temperature. With advice passed on through public television and radio networks, farmers can plan the types of crops and seeds they should plant in the coming growing season according to the climate expected. Since water temperature affects fish patterns, fishermen and fishing industries can anticipate what catch they might expect. If necessary, regulatory agencies can take measures to protect spawning stocks, thus avoiding the demise of commercially-important populations.

The advantages of climate predictions have already been demonstrated.

Peru's GNP and the gross value for the agricultural sector dropped drastically following the 1982-83 episode, but not during an event of 1986-87 after farmers were advised to expect below-normal precipitation. With no warning in 1987, grain production in Brazil's state of Ceara dropped to 15 per cent of the normal production. However, when ENSO forecasts and monitoring were applied to decision-making processes in 1991-92, grain production was 82 per cent of mean production.

Although some successful predictions have occurred, gaps remain in understanding of the phenomena, gaps that might be filled with more widespread reporting of temperature and rainfall variations and their application to more sophisticated and effective prediction procedures.

It would be extremely difficult and costly for any one country to gather all the information necessary to understand and predict climate variability. Since the effects of climate variation cross geopolitical borders, the pooling of information can enhance the data input into numerical models aimed at predicting climate change, and help determine the influences of topography and land- sea contrasts.

Participants at the IAI Lima workshop made the following suggestions for advancing scientific information about ENSO:

  • encourage an interdisciplinary approach to ENSO that looks not only at temperatures and rainfall but also at socio-economic issues;
  • include social scientists in the study of ENSO so they can serve as liaison between science, the general public and decision makers;
  • create and circulate a catalogue of models, modellers and researchers so scientists become aware of available information;
  • standardize data collection for easier exchange and digitize data to increase speed of compilation;
  • circulate a questionnaire that helps determine the data needs of various areas within the region;
  • identify an existing entity to serve as a repository for hemispheric data sets and improve its archives through the intercomparison of inventories;
  • make available selected long-term data from in situ observations and palaeoclimatic time series;
  • find ways to eliminate excessive costs for extracting data from some organizations;
  • encourage scientific exchange visits, e.g. visiting professorships, student exchanges, graduate programmes for foreign students and workshops; and
  • encourage IAI governments to continue funding existing research groups and to fund new groups.

The region lacks human resources to conduct the investigations that are needed. The improvement of data availability or communication facilities, although badly needed, are comparatively less urgent than training, development of new research facilities and reinforcement of existing ones.

The best data and forecasts will be of little use if the information is not passed on to decision makers and the general public. Participants recognized the difficulties of communication between the scientific and non-scientific worlds.

It was agreed that the IAI should encourage and support regional and national workshops on the societal impacts of ENSO, with interaction between social scientists, decision makers and media representatives.

Building a relationship with the media was considered especially important. The media, it was mentioned, will not work for science but it will work with science. If convinced of the interest society should have in ENSO, it will report information about that subject adequately.

Private industry should be brought into collaboration as it can supply information not published in scientific journals. Industry often worries that release of information might compromise its economic position. Companies need to be convinced that this is not necessarily the case and that cooperation will benefit society in general and, ultimately, them as well.

Further information

Inter-American Institute for Global Change Research, 1100 Wayne Avenue, Suite 1201, Silver Spring, Maryland 20910, USA. Fax: 1-301-5895711. Email: lara@ogp.noaa.gov.

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This article is based on material extracted from the report "El Nino-Southern Oscillation and Interannual Climate Variability". The report can be obtained by writing to the Inter-American Institute at the above address.