What was done
The authors review what is known about the natural climatic oscillation that produces El Niņos and La Niņas, focusing on the possibility that this oscillation may be influenced by global warming.

What was learned
The authors identify two primary causes for changes in the neutrally-stable oscillation that alternately gives the world El Niņos and La Niņas: random disturbances and variations in the background state of the climate.  This being the case, and since "the possibility that global warming is affecting those variations cannot be excluded," the authors are forced to conclude that "global warming is bound to affect El Niņo by altering the background climate," which is only logical.  But how will global warming, if it either is occurring or will occur sometime in the future, affect El Niņos?

Since the subject is such a complex one, as "changes in sea surface temperature are both the cause and consequence of wind fluctuations" - and these phenomena figure prominently in the El Niņo-La Niņa oscillation - it is not surprising that the authors conclude that current climate models do not do too good a job in answering this question.  As they report at the conclusion of their review, "several such projections have been made and yield results that differ from one another," and "at this time, it is impossible to decide which, if any, are correct."

What it means
The bottom line of this review by two eminently qualified students of the subject is that we just do not know what the consequences of significant global warming would be for future El Niņos.  And since we do not know if we are about to experience significant global warming (see our editorial of 1 July 2000: There Has Been No Global Warming for the Past 70 Years), and since it has not been proven that this most recent seven decades of non-warming has been caused by the historical rise in the air's CO2 content, it seems rather tortuous to claim that mankind is responsible for such things as recent coral bleaching episodes around the world.  It may be soothing to the soul; but it is anathema to the mind.