did they call for it? i'd suggest two attempts to call for la nina:
1) to the tune of 'la bamba'. la nina will like that. lala lala lala niiinnya. if la nina is around at all, it will respond.
2) using ernie's call and response, ala that time he went fishing with bert. heeeere lanina lanina lanina lanina lanina lanina. if la nina is around, it'll jump right out of the southern oscillation and into the research science boat, immediately.
at the end of the day, though, if la nina cannot be found, perhaps it doesn't want to be found.
my serious question is this: given the obvious reality of climate change and the observable effect of record increases in ocean temperatures, why were they looking for la nina at all?
la nina will return, but you'll have to recalculate her.
in the mean time, we will probably have several decades of schrodinger's la nina.