Does the occurrence of El Nino suggest a larger climate issue? Are there any long lasting positive/negative effects of El Nino? How does the global warming crowd view El Nino?

Are El Nino and La Nina manifestations of global climate change?

The El Nino Southern Oscillation, a periodic warming and cooling of the surface waters of the central and eastern equatorial Pacific Ocean, is an ongoing cycle of long duration. That is, as far back as weather records go, there is evidence of this seasonal variation.

El Nino is the warm phase of ENSO, and brings wetter conditions across the southern tier of the United States and parts of South America, and drought in the western Pacific. La Nina is the cold phase of ENSO.

Global climate impacts of La Nina tend to be opposite those of El Nino, NOAA explains, with the impacts of El Niño and La Niña at higher latitudes including North America most clearly seen in wintertime.

Some climatologists suggest it is logical to believe that the recorded warming of the atmosphere will have an impact on the frequency, duration, and severity of El Nino and La Nina events. As the atmosphere warms, heat would be transferred to the oceans, with the potential for increased extremes between cold and warm periods.

They also agree that the jury is still out on whether this likely scenario will occur, or is occurring, and what shape it will take.

"El Nino has a significant influence on global weather, ocean conditions and marine fisheries. El Niño, the periodic warming of central and eastern tropical Pacific waters, occurs on average every two to five years and typically lasts about 12 months," according to NOAA scientists.

"El Niño's impacts depend on a variety of factors, such as intensity and extent of ocean warming, and the time of year. Contrary to popular belief, not all effects are negative. On the positive side, El Niño can help to suppress Atlantic hurricane activity. In the United States, it typically brings beneficial winter precipitation to the arid Southwest, less wintry weather across the North, and a reduced risk of Florida wildfires.

"El Niño's negative impacts have included damaging winter storms in California and increased storminess across the southern United States. Some past El Niños also have produced severe flooding and mudslides in Central and South America, and drought in Indonesia.

"An El Niño event may significantly diminish ocean productivity off the west coast by limiting weather patterns that cause upwelling, or nutrient circulation in the ocean.  These nutrients are the foundation of a vibrant marine food web and could negatively impact food sources for several types of birds, fish and marine mammals," NOAA scientists report.