September 2, 1997
El Nino is a warming of the surface waters of the tropical Pacific Ocean whose far-reaching climatic consequences affect societies and economies around the globe. The emergence of a powerful new El Nino this year is good news for skiers and snowboarders, as El Nino events have coincided with excellent winter snow conditions in the American West.
The current El Nino
A strong El Nino has developed over the past several months.
According to the National Oceanic and Atmospheric Administration, waters across the eastern tropical Pacific have warmed to levels of 2 to 3 degrees Celsius above normal. Near the South American coast, waters are the warmest observed since the El Nino of 1982-83. That El Nino, the century’s strongest, triggered over $10 billion in weather-related damages worldwide. One signal of the current El Nino’s strength: for about 10 days last month, the northeasterly trade winds across the entire equatorial Pacific reverted to westerlies. Such a switch has been observed only once in the past 30 years – again, during the 1982-83 El Nino. If this event behaves as most do, the present oceanic signals of El Nino will continue to intensify during the summer and fall.
Colorado skiers remember the marvelous winter of 1982-83 fondly, as snow conditions were heavenly throughout the season.
El Nino and global warming
El Nino has been showing up more often since the late 1970s, with a prolonged episode from 1990 to 1995 and another quickly building up now. According to National Center for Atmospheric Research scientist Kevin Trenberth, one possible explanation is that the warm pool in the tropical western Pacific Ocean may be growing larger. Climate models are not yet accurate enough in simulating El Nino to clearly attribute these changes to global warming. However, even without affecting how often El Nino occurs or how long it stays around, global climate warming is likely to intensify the extremes of flooding and drought already experienced in different parts of the world during a normal El Nino and its inverse, La Nina. Trenberth believes that global warming and El Nino reinforce each other in their impact on the environment and society, primarily through their combined effects on the hydrological cycle and the repercussions for water supplies.