There have been at least two meetings that I know of which have had the title, "Is This [1997-98] the El Niño of the Century?" One was held in October 1997 in Peru on the eve of El Niño's impacts in that country. The other was held in April 1998 in Southern California following El Niño's major impacts in North America and, more specifically, in California. The media, and even policy makers, have many times over-referred to this El Niño as a record-breaker and as the Event of the Century.
To be sure, it is a healthy scientific question. But such a question raises other concerns of equal or greater importance. What, for example, are we going to measure to determine whether this El Niño was the true El Niño Event of the Century? From the standpoint of the public, people will consider this to have been the "winner" of the El Niño "Olympics," if the devastation associated with it in areas with which they happen to be familiar has been greater than in other years. They may also come to believe whatever the press reports or whatever a group of scientists decides. But the reality may be something we as a community of scientists (physical, biological, and social) do not want to hear: that El Niño is a natural phenomenon that we do not yet know well enough to answer this question.
We are in a position, as evaluators of El Niño who hold the public's trust, to say anything we wish to about El Niño, and much of the public will accept it. That being the case, we must approach answering this question ("Is this the El Niño of the Century?") with great care.
How, for example, do we want to measure this event? Do we focus on the degree of change (i.e., above average) in sea surface temperature of the central Pacific Ocean? Do we rely on how hot the water gets off the coast of Peru? Do we focus on how widespread its global impacts have been? Do we rely on the costs of the devastation associated with El Niño? Do we rely on the amount of media coverage, political interest, or public awareness of the 1997-98 El Niño to decide whether this El Niño has been the Event of the Century? Making such a designation requires much more care than we seem to be giving it.
I would argue that many of the El Niño events in this century could earn the distinction of the "El Niño of the Century." The 1925 El Niño was a devastating one to Peruvian communities and ecosystems. Although it was a phenomenon that at the time was little understood, even in Peru, it was enough of an event to capture the attention of the Peruvians. This is the year that Peruvians began to collect rainfall (and other) information in a systematic and serious way.
The El Niño of 1939-41 was more controversial. It was, until recently, labeled as the longest El Niño of this century, running across three years (according to some researchers). The 1957-58 El Niño could be considered for the "Olympic" title because it is the El Niño that was observed accidentally (i.e., it was not part of any planned scientific experiment) during the IGY (International Geophysical Year)taking place at that time. It sparked the interest of a small number of American scientists. It was the information gathered during the IGY that was central to UCLA Professor Jacob Bjerknes' identification of the links between changes in sea surface temperatures in the eastern equatorial Pacific (the earliest definition of an El Niño) and the see-saw pattern of sea level pressure systems in the western part of the Pacific basin (called the Southern Oscillation).
The 1972-73 event was the first to draw the attention of the public. It was a big event (although not the biggest, even up to that time), but its impacts on Peru's fishing industry captured the attention of the international press and of some researchers. One could easily argue that it was this El Niño that deserves the title of "El Niño of the Century," because it was the one that started researchers on the proverbial "slippery slope" of interest in the phenomenon on the part of an increasing number of scientists.
A mild El Niño in 1976 could legitimately seek to capture the title as well, but for reasons that are not so obvious. Researchers now seem to agree that there was some sort of change in the behavior of El Niño in the mid-1970s, following this event. (It is important to note that some researchers have referred to this as the 1976-77 El Niño, while others have suggested removing it from the list of legitimate El Niño events because it did not meet certain newly defined criteria.)
And then there is the 1982-83 event which, until recently, firmly held the title as the "El Niño of the Century." It was extraordinary in size, unexpected in its timing, and devastating in its impacts around the globe. It captured the attention of the scientific community to such an extent that funding agencies of governments supported their interest by investigating in a ten-year multinational research and monitoring effort known as TOGA (Tropical Ocean-Global Atmosphere). This El Niño is the one that resulted in public awareness to such an extent that such popular magazines as Reader's Digest (December 1983) and National Geographic (February 1984) produced articles about it. It is the event that led to the development of the excellent monitoring system known as the TAO Array across the equatorial Pacific, using satellites and on-the-spot (in-situ) measurements from fixed and drifting ocean buoys.
The 1986-87 event deserves special consideration, but not for its size, timing, duration, or impacts. It deserves recognition as having been the first El Niño to have been forecast to the public by researchers (i.e., Mark Cane and Steven Zebiak at Columbia University's Lamont-Doherty Earth Observatory). Their public prediction went against the existing (at that time) but unwritten forecasters' code not to go to the media with such experimental projections. Despite the grief they received at the time from the scientific community for "going public," it was only a few years before all groups trying to forecast El Niño's onset followed their lead and were going to the media with their projections.
The 1991-92 El Niño started out as a typical event. And it seemed to have spawned typical impacts around the globe, with droughts and floods falling in the approximate locations in which they might have been expected (e.g., Australia and Indonesia suffered major drought, while northern Peru and southern Ecuador suffered from excessive rains and flooding). But this El Niño did not go away. Late in 1992 it appeared to be in its decay phase; however in 1993 it re-emerged as another El Niño. It did this again in 1994. To the Australians, it was an event that caused a five-year drought in that country. To Peruvian fishermen, it appeared to be three successive, weak El Niño events with little impact on their highly productive coastal fishing operations. This extended El Niño prompted the public (at the instigation of some researchers) to blame global warming for such a long El Niño, now called by some the longest of this century (making it a contender for the "El Niño of the Century"). Two researchers gave the 1991-95 El Niño(s) a probability of occurrence of once in 2,000 years, a probability that has been challenged by other researchers.
And now we have the latest El Niño of 1997-98, perhaps (and I say this while biting my tongue) the last of the 20th Century. It, too, has manifested unusual (more correctly, unanticipated) characteristics. It developed earlier than expected, stayed strong longer than expected, grew bigger than expected, and was hotter than expected. On these characteristics alone it merits consideration as the "El Niño of the Century." But that is not all it did. It prompted the biggest media response of all previous events. It captured the attention and interest of most national policy makers around the globe. It sparked the development of numerous bureaucratic units to deal with the phenomenon and its impacts. It has been the most observed El Niño event ever, from its onset to its decay phase. Some scientists, policy makers, and members of the media have suggested (yet to be proven) that its impacts on societies and ecosystems around the globe have well surpassed those attributed to the previous El Niño champion, the 1982-83 event. This event captured its own daily news spot on CBS's Dan Rather show, along with mention on political and business news and sports! In essence, just about everything that happened during this El Niño (climate-related or not, legitimate or not) has been blamed on it.
But the last event of the century is drawing to a close. It is perhaps time for the judges to rank the performance of this event as compared to its earlier competitors. It is most likely that, regardless of indicators used by the various judges, the 1997-98 El Niño will go down in the public perception as the Event of the Century. Most people don't remember events before 1983. In fact, many people do not really remember the 1982-83 event (although we have been constantly reminded of it during the recent El Niño, because it was used for comparative purposes by scientists and the media).
As a lone judge, however, I would probably have to protest this search for the "Event of the Century" by throwing away my score card. Each of the events mentioned above had its own unique quality. Each event has contributed to our understanding of the El Niño process. I am afraid to say publicly that, while we know a great deal about this natural process, there is a great deal more that we still do not know. We must recognize this, not to dampen our optimism about El Niño research progress, but to avoid the pessimism that could ensue when we are surprised by the behavior of the next El Niño event.
Before we start ranking El Niño events, we ought to make explicit the indicators we are using to rank them. And we ought to recognize that others may be measuring and comparing El Niño according to different sets of indicators.
In a way, this essay has the ring to it of a parent responding to the question, "Which one of your children do you like best?" The answer, to the public at least, is likely to be, "I like all of them equally well." And she may be answering truthfully, but most likely she is measuring them each by different sets of criteria. The same is true for evaluating El Niño events. However, it is important to make the conditions (and indicators) surrounding our comparative assessments known so that our responses can be better understood and evaluated by others.