Is the Current El Niño Stronger Than the One in 1997/98?

Yesterday, NOAA published its weekly update of the sea surface temperature data for the NINO regions (data here), and because the sea surface temperature anomalies for “a key region” of the equatorial Pacific (the NINO3.4 region) exceeded the weekly values in 1997, alarmists from around the world are claiming the 2015/16 El Niño is the strongest ever, exceeding the strength of the 1997/98 El Niño. Example: the LA Times headline reads El Niño temperatures in Pacific Ocean break 25-year record.  The article by Rong-Dong Lin II and Roxanna Xia begins:

Temperatures in a key location of the Pacific Ocean are now hotter than they ever were in the record 1997 El Niño.

There are numerous other articles with the same underlying alarmism, including:

• The Washington Post:  By one measure, this wicked El Niño is the strongest ever recorded: What it means
• Mashable: The 2015 El Niño just crossed into record territory
• UN News Centre: El Niño on track to be among worst ever, but world better prepared for fallout – UN
• Ars Technica:  El Niño reaches record level for a single week period
• BBC News: ‘High impacts’ from globally stronger El Nino
• The Weather Channel: Strenthening [sic] El Niño Will Be Strongest on Record, WMO Says

The articles are focused on the sea surface temperature anomalies of the NINO3.4 region, which is bordered by the coordinates of 5S-5N, 170W-120W.  See Figure 1.  But as shown, the NINO3.4 region is only one of 4 often-used NINO regions.

Figure 1

The NINO3.4 region was created because it was better correlated to the “core of the ENSO phenomenon” than other NINO regions.  See Barnston et al. (1996) Documentation of a highly ENSO‐Related SST Region in the Equatorial Pacific: Research Note. In other words, the NINO3.4 region better reflected the typical El Niño and La Niña.

But it will be obvious to you that the NINO3.4 region does not capture the full strength of the 1997/98 El Niño! Why?  Because the 1997/98 El Niño was not at its strongest in the central Pacific.  The 1997/98 El Niño was an East Pacific El Niño, and it was strongest east of the NINO3.4 region.  The 1997/98 El Niño was unlike any El Niño that had been studied by Barnston et al. (1996).  And the current El Niño is also unlike the one in 1997/98.

ALL THE HUBBUB IS ABOUT THE NINO3.4 REGION SEA SURFACE TEMPERATURE ANOMALIES

Figure 2 compares the evolutions of the weekly NINO3.4 sea surface temperature anomalies for the years 1997 and 2015.  The sea surface temperature anomalies in this east-central region are obviously higher in 2015 than they were in 1997. So from that one metric, the alarmists are claiming the El Niño in 2015 is strongest ever.

Figure 2

Unfortunately, NOAA does not provide the uncertainties associated with that data.

BUT THE 1997/98 EL NIÑO EXCEEDED THE GOINGS-ON IN 2015 EAST OF THE NINO3.4 REGION

Figure 3 includes the evolutions of the 1997 and 2015 sea surface temperature anomalies for the NINO3 and NINO1+2 regions, which are east of the NINO3.4 region.  In 2015, sea surface temperatures in these eastern-most regions have not reached the values seen in 1997.

Figure 3

The farther east an El Niño is taking place, the greater impact it has on “normal” global weather patterns.

WHICH EL NIÑO LOOKS STRONGER TO YOU?

Figure 4 includes Hovmoller diagrams of equatorial sea surface temperature anomalies for the 1997 and year-to-date 2015 from the NOAA GODAS website. I’ve highlighted the longitudes of the NINO3.4 region on both Hovmollers.

Figure 4

The vertical (y) axis in the Hovmollers is time with the Januarys at the top and Decembers at the bottom.  The horizontal (x) axis is longitude, so, moving from left to right in each of the Hovmoller diagrams, we’re going from west to east…with the Indian Ocean in the left-hand portion, the Pacific in the center and the Atlantic in the right-hand portion.  We’re interested in the Pacific. The data are color-coded according to the scales below the Hovmollers. (Sorry about the different sizes of the Hovmollers, but somewhere along the line NOAA GODAS changed them, but they are scaled, color-coded, the same.)

In 1997, sea surface temperature anomalies east of the NINO3.4 region had reached 4.0 deg C as early as June, but we have yet to see those levels in 2015.

THE DATA PRESENTED IS NOT BASED ON THE “OFFICIAL” SEA SURFACE TEMPERATURE DATASET USED BY NOAA TO DEFINE EL NIÑO EVENTS

The data presented above and discussed in the linked articles are based on NOAA’s Optimum Interpolation sea surface temperature dataset (a.k.a. Reynolds OI.v2).  However, NOAA uses their “pause buster” ERSST.v4 sea surface temperature data for their “official” Oceanic NINO Index.  And as you can see there, this El Niño is running well behind the 1997/98 El Niño.  Also see Figure 5, which was presented in the November 12, 2015 blog post by Emily Becker November El Niño update: It’s a small world at the NOAA ENSO Blog.

Figure 5 (Source here.)

Their caption reads:

Ranking of August-October average sea surface temperature departures from the mean for all El Niño episodes since 1950. This measurement, the Oceanic Niño Index, uses ERSSTv4 data. Figure by climate.gov, data from CPC.

And their introduction to it reads:

First, a quick update on the recent El Niño indicators

The average anomaly in the Niño3.4 region during August-October of this year was 1.7°C, second to the same period in 1997 (1).

CLOSING

Please do not misinterpret what I’ve presented in this post.  I am not saying that the 2015/16 El Niño is not a strong event.  By all measures, we are in the midst of a strong El Niño. I’ll provide a full ENSO update next week.

-However-

Contrary to all of the alarmism, the 2015/16 El Niño is simply is not as strong as the 1997/98 El Niño based on the sea surface temperature anomalies of the eastern Pacific, east of the NINO3.4 region.

FOR THOSE NEW TO DISCUSSIONS OF EL NIÑO EVENTS

I discussed in detail the naturally occurring and naturally fueled processes that cause El Niño events (and their long-term aftereffects) in Chapter 3.7 of my recently published free ebook On Global Warming and the Illusion of Control (25 MB).  For those wanting even more detail, see my earlier ebook Who Turned on the Heat? – The Unsuspected Global Warming Culprit: El Niño-Southern Oscillation.