Myth: Karl et al. of the NOAA Misleadingly Altered Ocean Temperature Records to Increase Global Warming

The outline for this post is as follows:

1. The Myth and Its Flaw
2. Context and Analysis
3. Posts Providing Further Information and Analysis
4. References

This is the "main version" version of this post, which means that this post lacks most of my references and citations. If you would like a more comprehensive version with all the references and citations, then please go to the "+References" version of this post.

References are cited as follows: "[#]", with "#" corresponding to the reference number given in the References section at the end of this post

1.  The Myth and Its Flaw

The myth states that Thomas Karl and other researchers at the National Oceanic and Atmospheric Administration (NOAA) misleadingly, or fraudulently, altered sea surface temperature records in order to artificially increase the global warming trend. Karl et al. fabricated an analysis in this way in order to remove a recent "pause" or "hiatus" in global warming.

Purveyors of this myth include Congressman Lamar Smith, Congressman Darin LaHood, Congressman Andy Biggs (the three aforementioned legislators were members of a Congressional committee that offered mind-numbingly silly claims on climate science), JoAnne Nova, Fox News, David Evans, Ivar Giaever, Steven Crowder, The Daily Caller, Anthony Watts, Joe Bastardi, The Daily Mail, Tim Ball, Sonja Boehmer­-Christiansen, Bob Tisdale, Judith Curry, Fred Singer, Craig Idso, Roy Spencer, Anthony Lupo, Chip Knappenberger, Nir Shaviv, Patrick Michaels, Nicola Scafetta, John Christy, Ole Humlum, Joseph D'Aleo, Murry Salby, James Wallace III, William Happer, Matt Ridley, David Legates, The National Review, Ned Nikolov, Richard Lindzen, and numerous other people. Lindzen extends the myth by claiming (without citing any evidence) that most papers rejected the temperature adjustments made by Karl et al., consistent with Lindzen's history of making baseless accusations regarding temperature analyses.

The myth's flaw: Independent analyses validated Karl et al.'s post-1998 corrections, with some of this validating evidence coming from the myth advocate John Christy and from sources lauded by the myth proponent Judith Curry. Karl et al.'s data is also available online. In light of this, other researchers successfully used the same sea surface temperature record as Karl et al. And regardless of whether or not one accepts Karl et al.'s corrections, global warming continued after 1998, as I show in "Myth: No Global Warming for Two Decades" and section 2.1 of "Myth: The IPCC's 2007 ~0.2°C/decade Model-based Projection Failed and Judith Curry's Forecast was More Reliable". Moreover, the largest effect of Karl et al.'s corrections was not increasing recent warming, but decreasing 20th century warming. So one could hardly claim Karl et al. maliciously conspired to unjustifiably inflate the global warming trend.

A formal assessment of Karl et al.'s work also found no evidence of falsification or intentional distortion. The assessment notes that John Bates, the scientist who spearheaded the initial dubious attacks of Karl et al.'s research, oversaw an internal review of this research before it was published; Bates' review approved Karl et al.'s research for submission to the peer-reviewed scientific journal Science. Bates later criticized this internal review, though the formal assessment found no evidence that Bates publicly mentioned that he oversaw the review and approved the research for submission to Science. Furthermore, some reports indicate that tension existed between Karl and Bates, since Karl previously demoted Bates. Thus, not only do critiques of Karl et al.'s work fail on scientific grounds, but procedural critiques of their work originated from an unreliable source (Bates) who crafted a misleading narrative.


(This blogpost's twitter thread: https://twitter.com/AtomsksSanakan/status/996791100479295493)

2. Context and Analysis

Some individuals falsely claim that a recent "pause" or "hiatus" in global warming means that no post-1998 warming occurred; I rebutted this assertion in "Myth: No Global Warming for Two Decades" and section 2.1 of "Myth: The IPCC's 2007 ~0.2°C/decade Model-based Projection Failed and Judith Curry's Forecast was More Reliable". As an extension of this rebutted assertion, some people claim that Thomas Karl, and other researchers at the National Oceanic and Atmospheric Administration (NOAA), misleadingly adjusted recent temperature upwards in order to remove the "pause". Thus NOAA scientists exaggerated global warming by misleadingly adjusting temperature records. This is the myth this blogpost focuses on.

According to debunked myth proponents, Karl et al. made unjustified adjustments when transitioning from the Extended Reconstructed Sea Surface Temperature version 3b (ERSSTv3b) analysis to ERSSTv4. The myth collapses because Karl et al. provided clear justifications for their updates, as did other NOAA scientists.

NOAA scientists Huang et al. generated the ERSSTv4 updates, and also presented sound justifications for the updates almost 5 months before Karl et al. published their paper. Huang et al. cited previous research showing that buoy SST (sea surface temperature) measurements were systematically lower than ship SST measurements. They then used the SST data to generate a correction for this difference. The correction shifted the buoy data to match the ship data. Other research supported this correction, as Huang et al. made clear in subsequent research published in 2017. So Huang et al. addressed an issue noted by numerous climate scientists, instead of maliciously performing adjustments for no good reason.

Some myth proponents object to this correction by saying the NOAA changed good buoy to match bad ship data. But this objection fails miserably. Adjusting the buoy data to match the ship data results in the same warming trend (or temperature anomaly) as adjusting the ship data to match the buoy data. That should be obvious, and Huang et al. showed that to be the case. Huang et al. opted for the buoy-to-ship correction in ERSSTv4, since ship data was more readily available than buoy data in the past, allowing for an easier correction of buoy data to match the longer-term ship SST record.

In addition to this and other corrections, Huang et al. discussed data processing and uncertainties in ERSSTv4 in a 2016 paper; they also did this in a 2015 paper published months before Karl et al.'s work. Myth defender Judith Curry conveniently glosses over this when she claims the NOAA team did not pay sufficient attention to processing and uncertainties. 

Huang et al.'s 2015 paper provided further confirmation for ERSSTv4 by showing that ERSSTv4's post-1997 trend matched the trend from another SST analysis known as Centennial Observation-Based Estimates of SST Version 2 (COBE-SST2). Figures 1 and 2 below compare ERSSTv4, COBE-SST2, and ERSSTv3b for the post-1997 warming period:

Figure 1: Comparison of global sea surface relative temperature trends from 1997 - 2018 for COBE-SST2 and ERSSTv4. The warming trend over this time period is 0.138 K/decade for COBE-SST2 and 0.132 K/decade for ERSSTv4 (calculations for statistical significance are not included, nor are all the listed digits significant) [1]. This figure was generated using an online tool [2] summarized in a published paper [3].

Figure 2: Comparison of global sea surface relative temperature trends from 1997 - 2018 for COBE-SST2 and ERSSTv3b. The warming trend over this time period is 0.138 K/decade for COBE-SST2 and 0.083 K/decade for ERSSTv3b (calculations for statistical significance are not included, nor are all the listed digits significant) [13]. This figure was generated using an online tool [2] summarized in a published paper [3].

Myth proponents have no excuse for not being aware of Huang et al.'s work, since:

1. Huang et al. generated the ERSSTv4 analysis that Karl et al. used
2. Karl et al. cited Huang et al. 5 times in Karl et al.'s less than 3-page paper
3. Huang et al.'s paper was published almost 5 months before Karl et al.'s paper

So if myth proponents bothered to do basic fact-checking, then they would know Karl et al.'s ERSSTv4 matched another SST analysis.

Myth defenders Roy Spencer and Fox News argued that Karl et al.'s analysis conflicted with weather-balloon-based and satellite-based analyses that showed a "pause" in warming. But Spencer and Fox News' argument lacks merit since:

• Spencer and Fox News refer to weather balloons and satellites that measure warming trends in a lower atmospheric layer known as the troposphere. In contrast, Karl et al. examined temperature trends near Earth's surface, not a thick vertical cross-section of the troposphere. The troposphere and Earth's near-surface rapidly warmed in 1997 and 1998, in response to an ocean cycle known as ENSO (the El Niño-Southern Oscillation); during these two years, the troposphere warmed more than the near-surface. I depict this rapid temperature increase in "Myth: No Global Warming for Two Decades", discuss the mechanism behind it in "Myth: The Tropospheric Hot Spot is a Fingerprint of CO2-induced Warming", and present evidence that it was caused by ENSO in "Myth: El Niño Caused Post-1997 Global Warming". The larger tropospheric temperature spike skews shorter-term post-1997 and post-1998 tropospheric temperature trends relative to near-surface temperature trends. So it would not be surprising if Karl et al.'s shorter-term near-surface temperature trend differed from satellite-based and weather-balloon-based tropospheric temperature trends.

• The troposphere warmed post-1997 and post-1998, as shown in satellite-based analyses and weather-balloon-based analyses. Spencer's University of Alabama in Huntsville (UAH) satellite team under-estimates this warming for reasons I cover in "Myth: Evidence Supports Curry's Claims Regarding Satellite-based Analyses and the Hot Spot". 

• Spencer's UAH colleague, and fellow myth proponent, John Christy co-authored marine (sea) air temperature trend record that shows post-1997 and post-1998 warming, while according with the sea surface temperature trend results of ERSSTv4, consistent with other examples of using marine air temperature records to validate sea surface temperature records. This is rather telling, since before this Christy falsely insinuated that the NOAA's ERSSTv4 analysis remained deeply flawed, while accusing NOAA scientists of manipulating data. Similarly, ERA5 and ERA-I, two re-analyses lauded by the myth advocate Judith Curry, also show more post-1997 warming than ERSSTv4, as do other re-analyses. This again confirms ERSSTv4 did not exaggerate recent warming.  

Returning from the troposphere to Earth's near-surface: Hausfather et al. showed that in comparison to ERSSTv3b, ERSSTv4 better matches ocean temperature data from other sources, including buoys, floats, and satellites. This debunks myth proponents Judith Curry's and Bob Tisdale's use of these data sources to support the myth. Figures 3 and 4 below illustrate this point:

Figure 3: Comparison of sea surface relative temperature trends from 1997 to 2015 for different sources, relative to a 1997-2001 baseline. The sources are buoys, ERSSTv3b, ERSSTv4, and the European Space Agency Climate Change Initiative (CCI) [4, figure 1].

Figure 4: Comparison of sea surface relative temperature trends from 1997 - 2015 for different sources. ERSSTv3b and ERSSTv4 are compared to ocean heat measurements from Argo floats. Argo(H2008), Argo(APDRC), and Argo(RG2000) represent three different near-surface temperature data-sets derived from the Argo data. ERSSTv4 data is presented relative to a 1997-2001 baseline, while the other data sources are aligned to the 2005-2007 baseline for ERSSTv4 [4, figure S2]. 

Cowtan et al., three co-authors from the aforementioned Hausfather et al. paper, then published another paper comparing ERSSTv4 to another SST analysis known as the Hadley Centre Sea Surface Temperature dataset, version 3 (HadSST3). Cowtan et al. argued that island and coastal weather station data better matches ERSSTv4's higher post-1997 warming trend than HadSST3's lower post-1997 trend. Figure 5 below depicts this comparison:

Figure 5: Sea surface relative temperature trends and trend differences from 1997 - 2016 for coastal and island analyses, compared to HadSST3 and ERSSTv4 data from the same locations as the coastal and island analyses. Trends differences in the third column come with the noted uncertainty values [5, table 1]. 

Consistent with this, HadSST4, the update to HadSST3, supports the recent warming trend from ERSSTv4. This evidence rebuts myth advocates Watts' and Tisdale's use of HadSST3 to critique ERSSTv4. A similar problem arises for the myth defender Judith Curry, since she also used HadSST3 to cast doubt on Karl et al.'s use of ERSSTv4 in the NOAA global surface temperature analysis. Curry instead prefers other surface temperature analyses, as she notes during her discussion of temperature trends from 1998 - 2014:

"The surface temperature data sets that I have confidence in are the [United Kingdom] group and also Berkeley Earth [6]." 

Yet both Berkeley Earth's analysis and HadCRUT4 (United Kingdom's Hadley Center, Climate Research Unit Surface Temperature record) show warming from 1998 - 2014, with warming trends of 0.165 K/decade and 0.116 K/decade, respectively. HadCRUT4 and the NOAA's analysis under-estimate this warming due to their poorer global coverage; members of the Hadley Center team admitted to this with respect to HadCRUT4. Berkeley Earth's and HADCRUT4's 1998 - 2014 warming trends are higher than Karl et al.'s NOAA trend of 0.102 K/decade; thus these analyses undermine the myth that Karl et al. misleadingly exaggerated recent global warming. So once again Curry's cited sources rebut her objections to Karl et al.'s work with ERSSTv4.

(This illustrates Curry's habit of misleadingly discussing sources that undermine her position, as I discuss in "Myth: Judith Curry Fully and Accurately Represents Scientific Research". It also reflects Curry's history of misguided critiques against analyses that reveal post-1998 warming, as I show in section 2.2 of "Myth: Evidence Supports Curry's Claims Regarding Satellite-based Analyses and the Hot Spot".)

The Daily Mail, one of the main popularizers of the myth, failed even more egregiously than Curry did. The Daily Mail compared the Hadley Center's HADCRUT4 analysis to Karl et al.'s NOAA analysis from 1997 - 2017, without placing the analyses on the same baseline. This had the effect of illegitimately exaggerating the differences between the two analyses, which the Daily Mail used to claim that Karl et al.'s analysis did not match the "verified" data from the Hadley Center. 

Yet when one places the two analyses on the same baseline, the analyses have about the same 1997 - 2017 warming trend. In fact, HADCRUT4 has a slightly greater warming trend than the NOAA analysis (0.189 K/decade vs. 0.167 K/decade, respectively), which is the opposite of what The Daily Mail claimed with their distorted graph. The Daily Mail's distortion was so egregious that the Independent Press Standards Organisation (IPSO) required that The Daily Mail include a note on how The Daily Mail failed to correct their misleading graph. Of course, myth proponent Anthony Watts still uses this misleading graph with its obvious error, all without noting that the "verified" HadCRUT4 analysis debunks his myth. So even the sources relied on by myth proponents debunk the myth that the Karl et al. NOAA analysis misleadingly over-estimated recent warming.

Taken together, these comparisons indicate that Karl et al.'s use of ERSSTv4 compared favorably with other surface temperature analyses, SST analyses, and independent data sources. These comparisons also illustrate the importance of robust results produced by different research groups. Independent research groups apply different analysis methods to climate data. These research groups and methods serve as a check on one another, helping remedy the mistakes involved in any one research group or method. This is one reason why scientists use different approaches/methods to test a conclusion: the strengths of one method can compensate for the weaknesses in another method, so one knows that the results are not just due to the flaws of one particular method. This leads to consilient/convergent lines of evidence supporting a conclusion. 

NOAA researchers Huang et al. likely had this in mind when they compared ERSSTv4 results to other SST estimates such as COBE-SST2 and HadSST3. In contrast, myth proponents Watts and Tisdale cherry-picked HadSST3, while evading COBE-SST2. They then used this cherry-picking to claim that ERSSTv4 was a outlier when it came to SST analyses. One might suspect that Watts and Tisdale did this to evade the COBE-SST2 analysis that undermines their myth and supports the ERSSTv4 analysis (as I showed in figure 1).

These convergent lines evidence in support ERSSTv4 (over ERSSTv3b) also rebut Lindzen's unsupported claim that most scientists rejected Karl et al.'s use for ERSSTv4. Several papers used ERSSTv4, yet Lindzen conveniently failed to mention any of these papers. So contrary to what Lindzen claimed, many researchers used Karl et al.'s corrected ERSSTv4, instead of rejecting the corrections:

"[...] three widely used [sea surface temperature] reconstructions (HadISST 1.1 [...], ERSSTv4 [...], and COBE v2 [...]) [7]."

 
This remains in line with Lindzen's history of making baseless accusations regarding adjustments to temperature analyses. This quote also serves as an interesting contrast to Curry's politically-charged proclamation that:

"I personally see no reason to the use the NOAA ERSST dataset [...]. [...] So while I’m sure this latest analysis from NOAA will be regarded as politically useful for the Obama administration, I don’t regard it as a particularly useful contribution to our scientific understanding of what is going on [6]."

Ironically, Curry made this statement while citing John Kennedy. Kennedy undermines Curry's reasoning by using ERSSTv4, while pointing out that other scientists found reasons to use ERSSTv4 as well:

"[...] the current, commonly used, long-term gridded SST analyses: [...] HadSST3 [...] ERSSTv4 [....] COBE-SST2 [...] [8, page 1602]."

Curry also cites Hausfather et al.'s paper, even though that paper also states that ERSSTv4 is a commonly used SST analysis. So Curry's own sources again undermine her criticism of the Karl et al.'s use of the ERSSTv4 analysis.

Figure 6 illustrates the impact of Karl et al. incorporating ERSSTv4's newer corrections into the NOAA's global relative surface temperature trend vs. using older corrections:

Figure 6: Global land and sea surface relative temperature trends from 1880 - 2014 with newer ERSSTv4 corrections, older ERSSTv3b corrections, or without either correction. (A) The black line represents newer ERSSTv4 corrections, while the red line indicates older ERSSTv3b corrections. (B) The black line represents newer ERSSTv4 corrections, while the teal line removes this correction [9, figure 2].

Based on figure 6, the most striking correction is not removing a supposed post-1998 "pause" in panel A. Instead the most striking correction is the NOAA reducing 1880s - 1940s warming in panel B, thereby reducing industrial-era warming during the 20th century. So the most dramatic NOAA correction reduces warming, instead of exaggerating it. Yet myth proponents obsess over the much smaller post-1998 correction. 

This reveals quite a bit about the mindset of myth advocates: most ignored (willfully or otherwise) the NOAA reducing overall warming, thereby allowing the advocates to invent false narratives about the NOAA unjustifiably increasing warming. Myth defenders also largely ignored the COBE-SST2 analysis which came out before Karl et al.'s analysis and which matched Karl et al.'s work with ERSSTv4 (see figure 1). And most advocates did not bother to compare the ERSSTv4 corrections to COBE-SST2, even though NOAA researchers performed this comparison before myth advocates began whining about Karl et al.'s work. Myth proponents instead resorted to paranoia about Karl and the NOAA, with myth advocate Lamar Smith demanding to see NOAA researchers' e-mails. The myth defenders' paranoia here reflects the conspiracist mindset common in climate "skeptic" (or denialist) circles, especially in the work of myth proponents John Christy, Joseph D'Aleo, Judith Curry, and Bob Tisdale.
(In "John Christy and Atmospheric Temperature Trends", I summarize several examples of Christy misrepresenting climate science)

Since most myth defenders (other than Bob Tisdale) did not bother to address the NOAA's major 1880s - 1940s correction, it would be worthwhile to address that correction here. Sea surface temperature measurement practices significantly changed as a greater number of ships entered the sea during World War II. Observers on ships shifted from measuring sea surface temperature using buckets, to more often measuring temperature using engine intake thermometers. Engine intake estimates tended to be warmer than readings taken from buckets, as scientists knew since at least the early 20th century. Thus the shift in temperature monitoring practices caused 1940s measurements to be anomalously high, exaggerating the 1880s - 1940s warming trend. So the NOAA and other research groups applied a 1880s - 1940s correction to account for this, after performing experiments and analyses to estimate the effects of changes in temperature measurement practices. This research undermines Judith Curry's insinuation that scientists performed this correction just to remove warming they found inconvenient. 

Ironically, if her insinuation were valid, then it would also apply to her fellow contrarian and myth proponent John Christy, since Christy applied a large form of this 1940s correction to his marine air temperature analysis. Even Curry's fellow contrarian Bob Tisdale acknowledges the need for a correction, as Curry should know since she posted his acknowledgement on her blog. Moreover, in her published peer-reviewed work, Curry admits that such a mid-20th century correction is an advantage. So Curry is seemingly being two-faced in her objection; she casts aspersions on scientists' corrections when writing to the non-expert public, but speaks appreciatively of those corrections when writing to a more scientifically-literate audience. 

The aforementioned 1940s World War II bias does not strongly disrupt coastal and island data. So Cowtan et al. used coastal and island weather station data to argue that ERSSTv4's correction over-estimates 1910s - 1940s warming and under-estimates 1860s - 1910s warming. They also showed how ERSSTv4 contrasts with HadSST3 for various pre-1979 periods. Figure 7 below presents a comparison of the trends from these three analyses:

Figure 7: Sea surface relative temperature trends from 1850 - 2016 for a near-global coastal analysis ("Hybrid SST"), compared to HadSST3 and ERSSTv4 data from the same locations as the coastal analysis [5, figure 11].

So ERSSTv4 likely includes too small of a correction for the aforementioned changes in sea surface temperature monitoring during World World II. A number of consilient points support the idea that SST analyses such as (but not limited to) ERSSTv4 and HadSST3/HadSST4, along with the global surface temperature analyses that include them, thus over-estimate 1910s - 1940s warming and over-estimate 1940s - 1960s cooling. The consilience of these points helps strengthen the overall conclusion, as occurs in other scientific topics with consilient lines of evidence. These supporting points include:

1. thermometer, a.k.a. instrumental, data from coastal and island weather stations
2. three temperature trend re-analyses using surface observations, one of which was the product of a process Judith Curry called true progress and another which Curry says she prefers for global temperature trends
3. two temperature trend re-analyses that do not use thermometer data for air temperatures
4. non-instrumental analyses that use proxies
5. the Hadley Centre Sea Ice and Sea Surface Temperature analysis, also known as HadISST1
6. comparisons to other datasets using physical and historical evidence
7. the contrarian John Christy's 1941 - 1945 marine air temperature correction that is based on pre-1941 and post-1945 thermometer data, consistent with other examples of using marine air temperature records to validate sea surface temperature records
8. there is no known climate mechanism occurring at that time that would cause the stated pattern of both large, rapid cooling following the 1940s ERSSTv4 temperature spike and lack of concurrent strong cooling of land air temperature (for example, cooling from a volcanic eruption would not cause this pattern, but this pattern would occur with a shift between measuring SST more with engine intake thermometers vs. measuring SST more with buckets; even the contrarian Bob Tisdale notes this point)
9. models fairly accurately simulate industrial-era global surface temperature trends, except for the 1940s temperature spike from ERSSTv4; but models accurately simulate global surface temperature trends through this 1940s time-period, once one applies a correction based on coastal and island weather station data

(The last listed point above merits further explanation. When a model conflicts with an observational analysis in science, it often turns out that the model is right, while the observational analysis is wrong. A classic example of this involved climate models predicting warming of the lower atmosphere, while a satellite-based analysis failed to show this warming. Scientists then discovered numerous errors in this satellite-based analysis, as admitted by the scientists who originally generated it. Correcting those errors resulted in the analysis showing warming, as discussed in section 2.3 of "Myth: Santer et al. Show that Climate Models are Very Flawed"; that blogpost also provides examples from other branches of science in which models were correct, while observational analyses were wrong.

Along similar lines: if climate models are right, then it makes sense that correcting ERSSTv4's erroneously high 1940s values would bring the analysis more in line with climate models. One begs the question against climate models being accurate, if one assumes/insinuates without evidence, as Judith Curry does when speaking to the general public, that model accuracy does not explain why the 1940s adjustment brings the observational analyses more in line with the models. Begging the question against climate models remains as unacceptable as begging the question against models in other scientific fields, as discussed in response to objection 1 in section 3.1 of "John Christy, Climate Models, and Long-term Tropospheric Warming".) 

NOAA researchers Huang et al. did not address this 1940s issue in their transition from ERSSTv4 to ERSSTv5; instead ERSSTv5 has roughly the same 1850s - 1940s trend as ERSSTv4. However, Huang et al. used other data sources to confirm that ERSSTv5 represented an improvement over ERSSTv4. Despite ERSSTv5's improvements, ERSSTv5 and ERSSTv4 have roughly the same post-1979 and post-1997 warming trends. Figure 8 below makes this clear:

Figure 8: Comparison of global sea surface relative temperature trends from 1979 - 2018 for ERSSTv5 and ERSSTv4. The warming trend over this time period is 0.106 K/decade for ERSSTv5 and 0.110 K/decade for ERSSTv4 [10]. Temperatures trends for 1997 - 2018 are 0.140 K/decade for ERSSTv5 and 0.132 K/decade for ERSSTv4 [11] (calculations for statistical significance are not included, nor are all the listed digits significant) [10; 11]. This figure was generated using an online tool [2] summarized in a published paper [3]. 

Figure 8's results creates further problems for myth proponents. For instance, I previously discussed how some myth proponents illegitimately whined about the NOAA (supposedly) adjusting good buoy data to match bad ship data. Their complaint lacked merit since adjusting the buoy data resulted in the same warming trend as adjusting the ship data. Figure 8 clearly illustrates this point, since ERSSTv4 and ERSSTv5 end up with similar warming trends, even though ERSSTv4 adjusted the buoy data to match the ship data, while ERSSTv5 instead adjusted the ship data to match the buoy data. Moreover, figure 8's post-1979 trend debunks the idea that NOAA scientists continually adjust recent temperature trends upwards in order to exaggerate global warming, since the later ERSSTv5 analysis has about as much post-1979 warming as the earlier ERSSTv4 analysis. Figure 7's pre-1979 trend also undercuts this idea, by showing how the NOAA may have under-estimated pre-1979 warming.

To make matters even worse for myth proponents, Huang et al. showed that ERSSTv5 and COBE-SST2 better matched other data sources for recent warming than did HadISST. This represents another blow to the position of myth defenders Watts and Tisdale, since they cited HadISST in order to lambaste ERSSTv4. Watts and Tisdale also cite another analysis for this purpose: the NOAA Weekly Optimum Interpolation Sea Surface Temperature version 2 analysis (WOISST), which Tisdale and Watts call "Reynolds OI.v2". In addition to WOISST, the NOAA also produces the Daily Optimum Interpolation Sea Surface Temperature analysis (DOISST), which represents an improvement over WOISST.

Let's set aside the cognitive dissonance involved in Watts and Tisdale citing the NOAA's WOISST, while they also use the myth to unfairly smear the credibility of NOAA researchers. The main problem with Watts' and Tisdale's use of WOISST is that Huang et al. published a paper identifying an error with WOISST. WOISST included an incorrect comparison between ship data and buoy data, while ERSSTv4 and DOISST included a correct comparison. Huang et al. also showed that including satellite data in ERSSTv4 did not significantly change the recent warming trend. This provides further confirmation for the NOAA's corrections from ERSSTv3b to ERSSTv4. So the satellite data undermines Tisdale's and Watts' position, since these myth advocates say that the NOAA excluded the satellite data for the sake of a political agenda.

Figure 9 below depicts SST warming trends from the satellite-enhanced ERSSTv4, along with WOISST and DOISST:

Figure 9: Sea surface relative temperature trends, with the noted 95% confidence intervals, for ERSSTv4, ERSSTv4 with satellite data included (ERSSTv4SAT), ERSSTv3b, DOISST, and WOISST [15, table 1].

So not only were Watts and Tisdale wrong in their use of the WOISST analysis, but they also failed in their politically-charged conspiracist rhetoric on the NOAA's use of satellite data. Yet Tisdale continues to cite HadISST and "satellite-enhanced" WOISST (Reynolds OI.v2) as objections to ERSSTv4, even after he was shown Hausfather et al.'s analysis supporting the improvements made from ERSSTv3b to ERSSTv4. Tisdale's response looks a lot like science denialism, in which one refuses to accept scientific claims supported by strong evidence. The following quote illustrates this point:

"The crucial difference is that your colleagues will accept a scientific statement if provided with sufficiently strong reasons to do so. In contrast, climate science denialists, like other pseudoscientists, tend to be driven by motives that make them impossible to convince, however strong the arguments they are presented with [14]."

So while myth advocates engaged in paranoid ranting about the NOAA (on denialist blogs and other elsewhere), competent researchers made real contributions to the peer-reviewed scientific literature on SST analyses, as illustrated in figures 3, 4, 5, 7, and 9 above. NOAA scientists also continued improving their SST analysis. 

At this point, some myth defenders might feel tempted to say that all these other analyses and independent data sources involve the same fabrication as the NOAA's analysis. Similarly so for the formal assessment that found no evidence that Karl et al. engaged in falsification or intentional distortion. This myth defender response suffers from many of the same flaws I discuss in response to objection 1 in section 3.1 of "John Christy, Climate Models, and Long-term Tropospheric Warming". Such a desperate, ad hoc response amounts to nothing more than cascade logic, a hallmark of paranoid conspiracy theories:

"[Cascade logic] occurs when defenders of one conspiracy theory find it necessary to implicate more and more people whose failure to discover or reveal the conspiracy can only be explained by their alleged complicity [12]."

3. Posts Providing Further Information and Analysis

• Section 3.8 of part 2 of "John Christy and the Tropical Tropospheric Hot Spot"
• "Myth: No Global Warming for Two Decades"

4. References

1. https://www.esrl.noaa.gov/psd/cgi-bin/data/testdap/timeseries.proc.pl?dataset1=NOAA+ERSST+V4&dataset2=COBE-SST+2&var=SST%2FSkin+T&level=1000mb&var2=SST%2FSkin+T&level2=1000mb&fyear=1997&fyear2=2018&season=0&fmonth=0&fmonth2=11&type=1&climo1yr1=1997&climo1yr2=2018&climo2yr1=1997&climo2yr2=2018&xlat1=-90&xlat2=90&xlon1=0&xlon2=360&maskx=0&zlat1=-90&zlat2=90&zlon1=0&zlon2=360&maskx2=0&map=0&yaxis=0&bar=0&smooth=0&runmean=1&yrange1=0&yrange2=0&y2range1=0&y2range2=0&xrange1=0&xrange2=0&markers=0&legend=0&Submit=Create+Plot
2. "Web-based Reanalysis Intercomparison Tool: Monthly/seasonal time series" https://www.esrl.noaa.gov/psd/cgi-bin/data/testdap/timeseries.pl
3. "Web-Based Reanalysis Intercomparison Tools (WRIT) for analysis and comparison of reanalyses and other datasets"
4. "Assessing recent warming using instrumentally homogeneous sea surface temperature records"
5. "Estimating biases in sea surface temperature records using coastal weather stations"
6. "NOAA/NCDC’s new ‘pause-buster’ paper: a laughable attempt to create warming by adjusting past data"
7. "An ensemble of ocean reanalyses for 1815–2013 with sparse observational input"
8. "A call for new approaches to quantifying biases in observations of sea surface temperature"
9. "Possible artifacts of data biases in the recent global surface warming hiatus"
10. https://www.esrl.noaa.gov/psd/cgi-bin/data/testdap/timeseries.proc.pl?dataset1=NOAA+ERSST+V5&dataset2=NOAA+ERSST+V4&var=SST%2FSkin+T&level=1000mb&var2=SST%2FSkin+T&level2=1000mb&fyear=1850&fyear2=2018&season=0&fmonth=0&fmonth2=11&type=1&climo1yr1=1850&climo1yr2=2018&climo2yr1=1850&climo2yr2=2018&xlat1=-90&xlat2=90&xlon1=0&xlon2=360&maskx=0&zlat1=-90&zlat2=90&zlon1=0&zlon2=360&maskx2=0&map=0&yaxis=0&bar=0&smooth=0&runmean=1&yrange1=0&yrange2=0&y2range1=0&y2range2=0&xrange1=0&xrange2=0&markers=0&legend=0&Submit=Create+Plot
11. https://www.esrl.noaa.gov/psd/cgi-bin/data/testdap/timeseries.proc.pl?dataset1=NOAA+ERSST+V4&dataset2=NOAA+ERSST+V5&var=SST%2FSkin+T&level=1000mb&var2=SST%2FSkin+T&level2=1000mb&fyear=1997&fyear2=2018&season=0&fmonth=0&fmonth2=11&type=1&climo1yr1=1997&climo1yr2=2018&climo2yr1=1997&climo2yr2=2018&xlat1=-90&xlat2=90&xlon1=0&xlon2=360&maskx=0&zlat1=-90&zlat2=90&zlon1=0&zlon2=360&maskx2=0&map=0&yaxis=0&bar=0&smooth=0&runmean=1&yrange1=0&yrange2=0&y2range1=0&y2range2=0&xrange1=0&xrange2=0&markers=0&legend=0&Submit=Create+Plot
12. "Conspiracy theories in science"
13. https://www.esrl.noaa.gov/psd/cgi-bin/data/testdap/timeseries.proc.pl?dataset1=NOAA+ERSST+V3b&dataset2=COBE-SST+2&var=SST%2FSkin+T&level=1000mb&var2=SST%2FSkin+T&level2=1000mb&fyear=1997&fyear2=2018&season=0&fmonth=0&fmonth2=11&type=1&climo1yr1=1997&climo1yr2=2018&climo2yr1=1997&climo2yr2=2018&xlat1=-90&xlat2=90&xlon1=0&xlon2=360&maskx=0&zlat1=-90&zlat2=90&zlon1=0&zlon2=360&maskx2=0&map=0&yaxis=0&bar=0&smooth=0&runmean=1&yrange1=0&yrange2=0&y2range1=0&y2range2=0&xrange1=0&xrange2=0&markers=0&legend=0&Submit=Create+Plot
14. "Dealing with climate science denialism: experiences from confrontations with other forms of pseudoscience"
15. "Assessing the impact of satellite-based observations in sea surface temperature trends"