Does The Sea Surface Temperature Record Support The Hypothesis Of Anthropogenic Global Warming?
Guest post by Bob Tisdale
This post is an expansion on my earlier post Sea Surface Temperature Anomalies – East Pacific Versus The Rest Of The World. In that post, I broke the satellite-era Sea Surface Temperature (SST) anomaly data for the global oceans into two subsets. The volcano-adjusted East Pacific SST anomaly data (90S-90N, 180-80W) shows no rise for the past 30 years and the SST anomalies for the Rest-Of-The-World (90S-90N, 80W-180) rose in two easily discernable steps. I used period average SST anomalies to highlight the steps.
This post is also similar in content to the post How Can Things So Obvious Be Overlooked By The Climate Science Community? But in this one, I provided a better way to divide the decade-plus periods that run from the end of the 1986/87/88 El Niño to the beginning of the 1997/98 El Niño and from end of the 1997/98 El Nino to the beginning of the 2009/10 El Niño. This allows for a more consistent way to illustrate the actual Rest-Of-The-World SST anomaly trends between those significant ENSO events.
THE ONE-WORD ANSWER TO THE TITLE QUESTION IS NO.
The satellite-era Sea Surface Temperature record indicates they rose only in response to significant El Niño events. In other words, the Sea Surface Temperature data contradicts the IPCC hypothesis that most of the rise is caused by an increase in Anthropogenic Greenhouse Gases.
The fact that the satellite-era SST anomalies do not support AGW is very easy to illustrate with two graphs, Figure 1. They show the satellite-based sea surface temperature (SST) anomalies for two subsets of the global oceans, using Reynolds OI.v2 SST data that runs from November 1981 (the start of that dataset) to the current month of May 2011. The graph on the left illustrates the volcano-adjusted Sea Surface Temperature for the eastern Pacific from pole to pole (90S-90N, 180-80W). That area represents about 33% of the global ocean surface area. There are major variations from year to year caused by El Niño and La Niña events, but the linear trend is basically flat at +0.003 deg C per decade. In other words, there has been no rise in the volcano-adjusted Sea Surface Temperatures for that portion of the global oceans in almost 30 years. The graph on the right illustrates the volcano-adjusted SST anomalies for the rest of the world from pole to pole (90S-90N, 80E-180). The SST anomalies for this portion of the globe show two distinct upward steps with periods of relatively little (if any) rise between those steps. The upward steps are highlighted by the average SST anomalies for the periods between the upward shifts caused by El Niño-Southern Oscillation events. There is an upward step in 1987 that occurs in response to the 1986/87/88 El Niño, and there is an upward step in 1997, which is a response to the 1997/98 El Niño. Note how the Rest-Of-The-World SST data appears to be in the process of another upward step in response to the 2009/10 El Niño.
Figures 2 and 3 are full-sized versions of the volcano-adjusted East Pacific and Rest-Of-The-World SST anomaly graphs. These datasets were first discussed in my post Sea Surface Temperature Anomalies – East Pacific Versus The Rest Of The World, and they have appeared in my monthly SST anomaly updates since then. Two notes: The Sea Surface Temperature dataset used in this post is NOAA Optimum Interpolation, version 2 SST, also known as Reynolds OI.v2. And as noted during the discussion of Figure 1, both subsets have been adjusted for the effects of the explosive volcanic eruptions of El Chichon in 1982 and Mount Pinatubo in 1991. I performed a linear regression analysis on global SST anomalies to account for the impacts of the volcanic aerosols. This was discussed in the post linked above.
THE REST-OF-THE-WORLD SST ANOMALY TRENDS BETWEEN THE SIGNIFICANT EL NIÑO EVENTS
Above I described the Rest-Of-The-World SST data as having two distinct upward steps with periods of relatively little (if any) rise between those steps. Actually, the linear trend for the period between the El Niño events of 1986/87/88 and 1997/98 is -0.01 deg C per decade and for the period between the El Niño events of 1997/98 and 2009/10 it’s +0.001 deg C per decade. Refer to Figure 4. In other words, the volcano-adjusted Rest-Of-The-World Sea Surface Temperature anomalies rose in response the significant El Niño events of 1986/87/88 and 1997/98, and then the sea surface temperatures did not rise over the decade (plus) periods that followed.
To establish the periods between the significant El Niño events, I used the NOAA Oceanic Nino Index(ONI) to determine the official months of the 1986/87/88, 1998/98, and 2009/10 El Niño events.. There is a 6-month lag between NINO3.4 SST anomalies and the response of the Rest-Of-The-World SST anomalies during the evolution phase of the 1997/98 El Niño. So I lagged the ONI data by six months and deleted all of the Rest-Of-The-World SST data that corresponded to the El Niño events of the 1986/87/88, 1998/98, and 2009/10 El Niño events. Then I performed the trend analyses on the data for the two periods that remained.
There will be those who will attempt to downplay the trend analyses shown in Figures 4 by stating that I’ve excluded the data after June 2009 to hide a rise in SST anomalies. In reality, I’ve excluded that recent data because the 2009/10 El Niño appears to be causing yet another upward step as shown in Figure 3.
Unless Anthropogenic Greenhouse Gases only impacted Sea Surface Temperature Anomalies during the 1986/87/88 and 1997/98 El Niño events, there is no evidence of Anthropogenic Global Warming in the satellite-era Sea Surface Temperature data. The volcano-adjusted East Pacific Ocean Sea Surface Temperature anomalies have not risen in 30 years. For the Rest Of The World, the volcano-adjusted Sea Surface Temperature anomalies rose only during the El Niño events of 1986/87/88 and 1997/98, but between the 1986/87/88 and 1997/98 El Niño events and between the 1997/98 and 2009/10 El Niño events, there was no rise in the volcano-adjusted Rest-Of-The-World Sea Surface Temperatures.
I have presented and described ENSO and the multiyear aftereffects of ENSO in numerous posts over the past years. Links to many of them are listed under the heading of FURTHER INFORMATION.
ENSO is a process that periodically discharges heat from the oceans and redistributes warm waters from the tropical Pacific. ENSO also recharges the tropical Pacific Ocean Heat through a periodic increase in Downward Shortwave Radiation. In that respect, ENSO events are fueled by a periodic increase in natural radiative forcing (solar energy) over the tropical Pacific. When El Niño events dominate a multidecadal era, indicating the tropical Pacific is releasing and distributing more ocean heat than “normal”, global surface temperatures rise. The opposite holds true during epochs when La Niña events dominate.
SST anomaly data is available through the NOAA NOMADS website:
The GISS Global Stratospheric Aerosol Optical Thickness data is available here:
My first detailed posts on the multiyear aftereffects of ENSO events are:
Can El Nino Events Explain All of the Global Warming Since 1976? – Part 1
Can El Nino Events Explain All of the Global Warming Since 1976? – Part 2
Supplement To “Can El Nino Events Explain All Of The Warming Since 1976?”
Supplement 2 To “Can El Nino Events Explain All Of The Warming Since 1976?”
And for those who like visual aids, refer to the two videos included in:
La Niña Is Not The Opposite Of El Niño – The Videos.
The impacts of these El Nino events on the North Atlantic are discussed in:
There Are Also El Nino-Induced Step Changes In The North Atlantic
Atlantic Meridional Overturning Circulation Data
I’ve also written a rebuttal post to Tamino’s AMO Post. I hope to have a new post on the North Atlantic posted sometime soon.
The posts related to the effects of ENSO on Ocean Heat Content are here:
ENSO Dominates NODC Ocean Heat Content (0-700 Meters) Data
North Atlantic Ocean Heat Content (0-700 Meters) Is Governed By Natural Variables
Additional detailed technical discussions can be found here:
More Detail On The Multiyear Aftereffects Of ENSO – Part 1 – El Nino Events Warm The Oceans
More Detail On The Multiyear Aftereffects Of ENSO – Part 2 – La Nina Events Recharge The Heat Released By El Nino Events AND…During Major Traditional ENSO Events, Warm Water Is Redistributed Via Ocean Currents.
More Detail On The Multiyear Aftereffects Of ENSO – Part 3 – East Indian & West Pacific Oceans Can Warm In Response To Both El Nino & La Nina Events
Bob Tisdale has worked long and hard to provide well researched and informative content for us all here. May I suggest you buy him a beer? – Anthony