In examining the long term ENSO record implied by the Multi-variate ENSO Index, it’s apparent that there has been a marked decrease of months of La Nina and Strong La Nina and a commensurate increase of months of El Nino and Strong El Nino. What do these trends mean? Are ENSO events strictly internal? Or do they imply changes in net radiance? Is some of the long term temperature trend due to recent decades anomalously El Nino conditions?
The change of ENSO conditions is visible in the MEI record since 1950:
The change of ENSO conditions is also visible in the extended MEI record since 1871:
Simple comparisons of MEI and various CERES data do not immediately reveal any strong correlation, with the exception of outgoing longwave radiance ( Figure 4. ) interpreted as increased radiance due to the increased temperatures of El Nino.