The Scientific Issues Arising from El Niño 1997-98

The development of this record large El Niño event and its ensuing major effects on the nation's weather over an 8-month period created a scientific event of major proportions. Key science-related questions that developed during El Niño 97-98 included:

Who was issuing El Niño-based climate predictions and for what conditions?

What kinds of weather conditions were caused by El Niño?

What types of impacts were being projected as a result of the El Niño weather?

How accurate and useful were the El Niño-based climate predictions?

How accurate were the oceanic predictions relating to the development, intensification, and dissipation of El Niño 97-98?

Was the record sized event caused by global warming?

Answers to such questions define the scientific information transmitted to the public, scientific community, and decision makers during the event. This assessment focused on the scientific information that appeared during the period from May 1997 to June 1998, but it also included information appearing a few months after El Niño ended (into early 1999) since these issuances reflect the thoughts and findings being generated by scientists during the event.

The scientific issues garnering the most attention were 1) attribution of various weather events on El Niño, 2) the relationship between El Niño and global warming, and 3) the projected impacts expected from the climate forecasted conditions. All threee issues were filled with debate, got major media attention, and all created a confusing perspective amongst the public. This paper addresses the various viewpoints expressed on these issues and the sources of the views.