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 source: NOAA | THE WRATH OF EL NIÑO October 3, 1997 |
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Return to this forum's introduction.
Questions answered in this forum:Where does El Niño get its energy? Will this El Niño be the biggest in 150 years? How does the NWS model El Niño? Does El Niño have any positive effects? What factors determine the frequency of El Niño? Who will suffer the most from El Niño?
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The National Weather Service's Climate Prediction Center page on El Niño.
Brent Fullmer of West Valley City, UT, asks: What gives El Niño it's energy? Magma? Is this a sign of increased volcanic activity? Or is just warming from the sun? Is this a sign of global warming? Thanks for your input.
Dr. Robert E. Livezey of the National Weather Service responds:
Dear Mr. Fullmer,
The so-called El Niño/Southern Oscillation (ENSO), which includes La Nina as well,is the most prominent part of coupled atmosphere-ocean variability. In that context, it ultimately derives virtually all of its energy from the sun, just like most other weather and climate phenomena. What makes ENSO so interesting are the processes whereby solar energy drives the wind and current systems of the globe and the particular imbalances that occur in these systems that eventually lead to the irregular El Niño/La Nina cycle. When the easterly trade winds in the tropics have been blowing strongly for a very long period period of time water builds up in the western Pacific Ocean. If these trade winds relax a sequence of events can slowly unfold that leads to an El Niño episode.
It has been hypothesized that one of the "triggers" for this process, i.e. ways to set the chain of events in motion, is a major volcanic eruption, but the evidence for this is somewhat thin and the idea does not enjoy much acceptance. As for global warming, El Niños have been occuring at irregular intervals as far back as direct or good proxy evidence is available, so the existence of the latter doesn't depend on the former. The question of whether the frequency and strength of the ENSO cycle is being impacted by global change is more difficult to answer, but I will take a crack at it in my response below to another forum participant.
Will this be the biggest Niño in 150 years?
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