The dialogue between Dr. Pielke Sr. and SkS has run its course, for reasons we will discuss below. The blog posts associated with this dialogue can be viewed here:
Dr. Pielke's final summary of the dialogue can be viewed here; however, it misrepresents the SkS arguments and the discourse in general several times, as we will show.
In attempting to re-calculate the CO2 contribution to the net positive radiative forcing, we showed that Dr. Pielke had made a number of errors, and the correct value was close to 50%, consistent with the findings of the IPCC. Dr. Pielke agreed with some of our corrections, but came up with new, equally incorrect reasons why the CO2 contribution must somehow be significantly less than 50%. However, although Dr. Pielke seems to still believe the value is lower, he has provided no references which would significantly alter the SkS calculations. Dr. Pielke claims:
"SkS accepts a lower value of the positive radiative forcing from soot (black carbon), dismisses two other aerosol effects from NRC 2005 and ignores that some of the radiative effect from the added CO2 would have been adjusted for by a warmer climate system since its introduction."
This is simply a mischaracterization of our position. SkS used the most up-to-date radiative forcing estimate for black carbon, which is larger than the IPCC estimate (and also noted that one previous study estimates the value is higher), did not "dismiss" aerosol effects, and did not "ignore" Dr. Pielke's so-called "adjustment" from a warming climate. In fact, we noted that Dr. Pielke's "adjustment" (which he did not account for in his own calculations, or justify other than referencing a personal communication) does not apply to our discussion of the radiative forcing and temperature changes over the past century.
Dr. Pielke argued that the current radiative forcing is more important than the change in forcing (though he did not provide an estimate of the current forcing), but we disagree. A long-term climate change is caused by a change in radiative forcing. That is why we were interested in calculating the contribution of CO2 and the net anthropogenic forcing to the global warming over the past century. Dr. Pielke refused to estimate these values, and did not provide any reason to doubt the SkS best estimates of 0.79°C average global surface warming from CO2, and 0.65°C from the net anthropogenic forcing (the discrepancy in the figures being due to cooling from aerosol emissions).
About ocean heat content, in his latest blog post, Dr. Pielke claims (emphasis added):
"warming on the upper ocean has been reduced in recent years. SkS spent a lot of time trying to argue that this is not significant and that one needs to perform statistical tests to show it is...I agree we can not say anything about the long-term trends, but to ignore that heating of the upper ocean has mostly stopped ignores the obvious."
Dr. Pielke's recollection here is simply wrong. We originally raised this issue because Dr. Pielke had claimed on his blog that OHC has not increased whatsoever ("~0 Joules", as he put it) since 2003. We demonstrated that this claim was false, and Dr. Pielke admitted his error (although he has not revised the erroneous blog post). However, contrary to Dr. Pielke's account, we specifically noted
"We agree that increase in OHC for the upper 700 meters has slowed in recent years."
Note that while the heating of the upper 700 meters has slowed, the heating of the upper 1500 meters has not, nor has the heating of the upper ocean "mostly stopped," as Dr. Pielke incorrectly claims. We did not delve into the statistical significance of the reduced upper 700 meter OHC trend, but rather noted that the warming in the deeper oceans has compensated for the slowed upper ocean warming:
"as we discussed in the post above, and Rob P's recent post, and John's post today, heat is also accumulating in the oceans at depths below 700 meters."
Figure 1: Total Global Heat Content from Church et al 2011
Dr. Pielke seemed reluctant to admit that the deeper oceans have warmed, making several statements along the lines of "If there is heat accumulating at depth...if the heat is actually there," and on his blog he continues to focus exclusively on the upper 700 meters of the oceans. However, as we have noted several times, there is nothing magical about the 700 meter depth. The ARGO data extends down to 1500 meters, and other studies have measured the yet deeper ocean layers. The data show that they have warmed, as illustrated in Figure 1. We are somewhat puzzled as to why Dr. Pielke has such a difficult time accepting these data.
With regards to the lower tropospheric temperature (TLT) data, Pielke similarly misrepresents the statements made by SkS on the subject.
"with respect to lower tropospheric temperature trends, they similarly conclude that any short-term excursion from a long-term linear warming is “noise” due to natural climate variations. Maybe they are right. However, to ignore the obvious that the warming of the lower troposphere has halted, when averaged over the time period 1998 (or 2002) to the present, ignores the obvious signal in the data."
Dr. Pielke seems rather confused in this statement, first correctly acknowledging that short-term variations are noise, and then claiming that they are "obvious signal in the data" in the very next sentence!
It's also only possible to say that the TLT warming trend has "halted" if we cherrypick the perfect start date and data set, as Dr. Pielke did. And once again, contrary to Dr. Pielke's account, we specifically and repeatedly acknowledged that the TLT trend has slowed in recent years (i.e. here and here and here). We also noted several times that the reduced trend over a short timeframe is not unexpected (see Santer et al. 2011), and in fact when we examine the various short-term temperature influences (i.e. ENSO, solar irradiance, aerosols), the slowed warming is even an expected result. Rather than examining the causes of the short-term slowing of the TLT warming trend, Dr. Pielke criticized SkS for doing this analysis, saying
"the failure to accept a slowing down of the tropospheric warming, which seems so obvious to me, actually prevents a more constructive discussion with the so-called "skeptics"."
In short, Dr. Pielke seems to believe we should cherrypick data, refuse to examine the causes of short-term temperature changes, and generally lower the quality of our scientific and statistical analysis in order to pander to the so-called "skeptics." We could not disagree more, and believe Dr. Pielke's is an unscientific approach.
Dr. Pielke claims
"Now, what SkS ignored in my questions to them was the lack of cooling in the lower stratosphere since about 1995"
We did not ignore this question - there were many questions going back and forth during our discourse, and if Dr. Pielke asked one about stratospheric cooling, we simply missed it. In searching back through the dialogue, we were only able to find one brief mention of the stratospheric temperature trend, which we did indeed respond to.
Regardless, this is not a difficult question to address, as many different factors influence stratospheric temperatures, including water vapor, aerosols, incoming solar radiation, ozone etc. For example, we recommend that Dr. Pielke read Seidel et al. (2011), emphasis added:
"The temporal and vertical structure of these [stratospheric temperature] variations are reasonably well explained by models that include changes in greenhouse gases, ozone, volcanic aerosols, and solar output, although there are significant uncertainties in the temperature observations and regarding the nature and influence of past changes in stratospheric water vapor."
Throughout the dialogue, Dr. Pielke accused SkS and our commenters of being "snarky." To this point we have ignored these accusations, because we are interested in discussing science, and accusations about the tone of the dialogue simply serve as a distraction However, it's worth noting that Dr. Pielke made quite a few "snarky" comments of his own. Dr. Pielke concludes his latest blog post saying
"I suspect many readers turn off SkS because of the tone they use in the comments."
Frankly, this is an absurd statement. The tone of comments on SkS in general is among the most civil in the climate blogosphere. We invite Dr. Pielke to compare the tone in the SkS comments to the tone in the comments of the blog of the man he defends so vigorously, Anthony Watts (whose tone is orders of magnitude more caustic than at SkS), and then to compare the scientific content of the posts. We consider the scientific content to be the most important part of the debate.
Dr. Pielke also accused SkS of reluctance to discuss science.
"Despite a rocky start (e.g. see) they finally engaged in constructive interactions"
We would like to reiterate that this dialogue began with Dr. Pielke falsely accusing SkS of ad hominem attacks on Spencer and Christy. When we pointed out that the series in question examine the scientific claims of those individuals, and thus by definition are not ad hominem attacks, it was Dr. Pielke who refused to discuss the science contained therein, instead changing the subject and trying to make us chase his Goodyear blimp, which we eventually did. Our reluctance to do so was obviously not because we are hesitant to discuss climate science, but rather because we expected Dr. Pielke to examine the scientific series which he wrongly attacked (which unfortunately, he never did, as he continued to wrongfully accuse SkS of failing to examine Spencer's scientific research).
We should also note that Dr. Pielke's repeated evasion and unwillingness to answer direct questions was substantially responsible for the argumentative tone of the discussion. For example, had he simply accepted our corrections to his radiative forcing calculations, rather than coming up with new incorrect reasons why the human contribution must be much lower than 50%, we would have been able to proceed to discuss other issues rather than continuing to argue this point.
Finally, Dr. Pielke claims about one of our weekly cartoons,
"the disclaimer to the contrary in one of the comments, clearly is intended to relate to me "
Several SkS contributors explained to Dr. Pielke that the cartoon was clearly not intended to depict him. It was merely a strange coincidence that one of the characters in the cartoon (which SkS did not create) was named "Roger" (hardly an uncommon name). Unlike Anthony Watts, SkS does not create or publish cartoons which mock specific individuals.
It is well worth reiterating that Dr. Pielke and SkS agree on the importance of reducing CO2 emissions. As Dr. Pielke put it (emphasis added):
"The emission of CO2 into the atmosphere, and its continued accumulation in the atmosphere is changing the climate. We do not need to agree on the magnitude of its global average radiative forcing to see a need to limit this accumulation. The biogeochemical effect of added CO2 by itself is a concern as we do not know its consequences. At the very least, ecosystem function will change resulting in biodiversity changes as different species react differently to higher CO2. The prudent path, therefore, is to limit how much we change our atmosphere."
Unfortunately, Dr. Pielke and SkS disagree on the approach we should take to reach that goal of emissions reductions. The climate "skeptic" community has the exact opposite goal - to prevent significant action to reduce CO2 emissions. In order to achieve that goal, climate "skeptics" spread misinformation and attempt to sow doubt in the minds of the public and policymakers (this includes some of the colleagues Dr. Pielke has so vigorously defended).
SkS believes that the most effective way to achieve the emissions reductions goal is to counteract this misinformation by examining what the body of peer-reviewed scientific literature has to say about it. Dr. Pielke, on the other hand, seems to constantly try to feed these "skeptics" ammunition for their arguments. For example, as we have discussed here, Dr. Pielke cherrypicked data in an attempt to argue that TLT and OHC have not increased since 1998/2002/2003/etc. in an attempt to argue that the warming has stopped. The "skeptic" interpretation of these comments could not be easier to predict - "Dr. Pielke says that global warming stopped a decade ago." We fail to see how this behavior will help us further the goal of reducing greenhouse gas emissions.
Dr. Pielke also frequently focuses on what we don't know about the climate, for example, quote mining recent statements by various climate scientists and emphasizing uncertainty, concluding (emphasis his):
"These extracts from the Greenwire article illustrate why the climate system is not yet well understood. The science is NOT solved."
Of course the science is "not solved." Science is never solved. And there are certainly aspects of the climate system which we do not yet understand well. But there are also aspects of the climate system which we do understand well, to the point that we BOTH agree regarding the need to reduce greenhouse gas emissions. As Dr. Pielke admits, we know that CO2 and other greenhouse gases are first order forcings which, if we continue to dump more and more of them into the atmosphere, will continue to cause more and more global warming and climate change. So what do we gain by inflating the uncertainties, especially when we know uncertainties cut both ways?
We know what the result will be - the "skeptics" will gleefully (and predictably) exploit these uncertainties as an excuse to oppose taking action to address climate change. In short, Dr. Pielke's behavior undermines his stated goal of reducing greenhouse gas emissions and addressing climate change. We recommend that Dr. Pielke stop sabotaging his own goal and instead implement a new policy: DNFTD (Do Not Feed The Delayers).
Posted by dana1981 on Saturday, 29 October, 2011
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