One year ago, altimetry monitored the growth of an important El Niño phenomenon. A warm water mass corresponding to a higher-than-normal sea level (July 8, 1997 map), shown as a red zone on the map, was near American coasts, and brought climate perturbations.
One year later, a cold water mass moves towards America, a phenomenon called La Niña. Its importance is nowaday difficult to forecast - and so are its consequences.

See also:

• El Niño

Websites on this subject:

• Scientific website:
  Climate Prediction Center Homepage (Noaa)
• Educational website:
  El Niño Primer (Nasa)