What was done
The authors analyzed the varve thickness profiles of two sediment cores retrieved from the Santa Barbara Basin off the coast of California, USA, to determine how the strength of the El Niņo/Southern Oscillation (ENSO) phenomenon has varied there over the past 15,000 years.

What was learned
The strength of the ENSO signal fluctuated on multi-decadal to centennial timescales throughout the 15,000-year record.  In spite of this variability, Nederbragt and Thurow note that power spectra analysis gave no indication of a unidirectional trend in the either the frequency or amplitude of ENSO events.  In fact, the ENSO signal at millennial timescales was reported to be "more or less constant."

What it means
In spite of the fact that earth's climate has varied from near glacial conditions to maximum Holocene warmth during the past 15,000 years, there has been no long-term trend in the frequency or intensity of the ENSO signal recorded in the varved sediments of the Santa Barbara Basin.  This finding is incredibly important, for it suggests that ENSO variability is independent of earth's mean climatic state.  Consequently, and in contrast to recent climate-alarmist claims, the ENSO signal of the past several decades remains well within its range of natural variability and likely will not be influenced by any global warming that might occur in the future.