First, the global average sea surface temperature change over time since 1991, as shown below:
We see 2015 as the warmest year for SST, with a marked increase since 2012. A similar sharp rise was seen in 1997/8, which was also the result of a major El Nino event. As then, it is likely that the global SST will drop down again during 2016 to temperatures more typical of recent years.
The warm water associated with the El Nino event is obvious right across the equatorial Pacific in the map for December 2015, corresponding to the last point on the time series above:
We have the recent El Nino as being the record event in the classic El Nino "3.4 region" -- although the margin compared to the 1997/8 event is close enough that we won't be confident of its record-holding status until we have done the proper job on SST CCI reprocessing:
In contrast, the anomaly in the "4 region" is clearly stronger in our data than for the earlier event, indicating that the hot action was located further west than in 1997/8.
On a final note, it is a pity that the next dual-view instrument, Sea and Land Surface Temperature Radiometer (SLSTR), missed the action of 2015, but in the project we are all very pleased that it has successfully been launched. Looking forward to working on the data.