Sep 13 2007
Reaction to Presentation by Dr. Roger Pielke
A few weeks ago, I attended a talk give by Dr. Pielke. Here is my reaction.
Dr. Pielke talked about a wide variety of topics at this seminar, and it would be almost impossible to cover them all here, so I will only touch on a few key points. Firstly, he talked about the radiative forcing components as discussed in the IPCC SPM 2001. He said that only 30% of the positive radiative forcing comes from CO2. I thought it was interesting that he used the 2001 numbers instead of the 2007 numbers. If one used the 2007 numbers, CO2 forcing accounts for over 50% of the positive forcing. And if one includes both CO2 and CH4 radiative forcing, it accounts for over 2/3 of the positive radiative forcing. Given that over 50% of the positive forcing comes from CO2, it makes sense to me that we should be focusing policy decisions on CO2, contrary to what Dr. Pielke said.
He also talked about needing to make a distinction between climate policy and energy policy. He says, “the current IPCC focus is to use the focus on CO2 to promote changes in energy policy.” While I don’t know if it’s true that the IPCC wishes to change energy policy, I don’t think they can easily be separated. Randerson (1997) show that the contribution from fossil fuels contribute a substantial amount to atmospheric carbon dioxide levels. For instance, “at Seychelles the contribution from fossil fuels [in comparison to the terrestrial biosphere component] increased from 22% in 1961 to 42% in 1990.”
Dr. Pielke also talked about the differences between the observed trends in the temperature data at the surface and in lower troposphere compared to GCM results. The report cited [Santer, 2005] states, “Observed results are close to the model average TS trend of +0.16ºC/decade. There is no evidence that the models significantly over- or underestimate the observed surface warming,” yet Dr. Pielke showed images of several stations of the USHCN (United States Hydroclimatology Network). He offered no explaination of how these pictures showed any evidence of a warming or cooling bias in the surface temperature trends. The large difference in the temperature trends between the observations and the models in not at the surface but in the lower troposphere. The model results for the lower tropospheric temperature trends are highly skewed, with most of them being low values (<0.2 C/decade), but a small number of higher values which distort the mean value towards the higher values. In either case, the RSS value for the lower tropospheric temperature trend is very close to the median and the mean values of the model results. It is unclear if this was published before or after the error was found in the UAH temperature trends which increased them and brought them closer to the RSS values.
Finally, he talked about using ocean heat content (measured in Joules) as a metric for climate change. Using a measurement of energy is a good idea for measuring changes in the climate system. However, it is a difficult measurement to make, especially given the poor spatial and temporal sampling of the past. Also, Dr. Pielke’s reliance on one paper [Lyman et.al., 2006] which shows cooling [reduction of joules], is suspect given the numerous other papers which show warming [addition of joules] [for example, Levitus (2001), Levitus (2005), AchutaRao (2006)].
References:
AchutaRao, K. M., B. D. Santer, P. J. Gleckler, K. E. Taylor, D. W. Pierce, T. P. Barnett, and T. M. L. Wigley (2006), Variability of ocean heat uptake: Reconciling observations and models, J. Geophys. Res., 111, C05019, doi:10.1029/2005JC003136.
Levitus, S., J. I. Antonov, J. Wang, T. L. Delworth, K. W. Dixon, and A. J. Broccoli (2001), Anthropogenic warming of Earth’s climate system, Science, 292, 267? 270, doi:10.1126/science.1058154.
Levitus, S., J. Antonov, and T. Boyer (2005), Warming of the world ocean, 1955 - 2003, Geophys. Res. Lett., 32, L02604, doi:10.1029/2004GL021592.
Lyman, J.M., J. Willis, and G. Johnson, 2006: Recent cooling of the upper ocean. Geophys Res. Lett., 33, L18604, doi:10.1029/2006GL027033.
Randerson, J.T., M.V. Thompson, T.J. Conway, I.Y. Fung, C.B. Field, The contribution of terrestrial sources and sinks to trends in the seasonal cycle of atmospheric carbon dioxide, Global Biogeochem. Cycles, 11(4), 535-560, 1997.
Santer, et.al., Temperature Trends in the Lower Atmosphere - Understanding and Reconciling Differences: How well can the observed vertical temperature changes be reconciled with our understanding of the causes of these changes?, 2005.
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4 Responses to “Reaction to Presentation by Dr. Roger Pielke”
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These arguments will be familiar to regular readers of Climate Science, a point you made when you first mentioned the talk. Of the three/four points he covered, I don’t claim to understand the one about joules, though Steve Bloom has clearly expressed views on this. OHC may be a useful measure of warming, but it is incredibly hard to get a large enough network in place to measure it at all (ARGO is okay, but this is still only 3000 buoys for the entire world’s ocean). There is also no meaningful historical database, and by the time any trends could be observed, arguments about AGW will be over.
The argument about the surface temperature record is not trivial, but it is deceptive. I am happy to accept that the averaged numbers are going to be hard to change unless large proportions of the databases can be shown to be inaccurate; this isn’t going to happen; simply, recent warming is not a case of mismeasurement.
Two or three of Roger’s arguments are, in my opinion, of some importance. Firstly, the argument that too much emphasis is placed solely on CO2, leading to important failures in communication of other significant risks (though I’d say that this imbalance has been addressed somewhat in the most recent literature). His interpretation of this as a political decision, rather than a function of the apparent significance of the forcing, is less defensible, though I’m not in the ‘charmed circle’, so I wouldn’t presume to call him out on this.
Another point, which you don’t mention, so he may not have, is that policy is made at regional levels, and is currently based on models with large degrees of uncertainty attached; in the struggle to get the key points across, this is somewhat overlooked in the SPM, even though it has implications for policy decisions.
Finally, Roger’s ‘vulnerability paradigm’ is not to be taken lightly, as it emphasises the significance of international cooperation and the responsibility of developed nations to work with their less powerful neighbours.
Now look what you’ve done; I’m sounding like an apologist for RPSr. All I want to point out is that he is a proper scientist- not a shill - with some proper issues, and people should be careful about passing judgement on him (as if they have the right): btw, I’m not suggesting you have done so at all.
Regards,
Dr. Pielke did talk about ‘vulnerability paradigm’ and the fact that policy is made at regional levels. I was trying to stay away from the policy aspect of his talk since this blog is supposed to be about science and not policy. However, some aspects of policy did slip in to the post because it was a major focus of the talk.
In fact, Dr. Pielke made many, many more points than the ones stated here. I reduced them down to the ones I thought were the most important to blog about - the ones that I didn’t agree with, which was only a small percentage of his talk. This does not mean that I think Dr. Pielke is a shill; I respect him as a scientist. But that doesn’t mean I can’t disagree with him, or think that he’s wrong about certain topics.
He didn’t mention that Lyman et al had been retracted due to subsequently discovered errors in the ARGO and XBT data?
[Response: He said it had been revised, not retracted. He showed the (unpublished) "revised" line which was essentially constant in the last three years. It looked like the trend was still towards cooling, but with such large error bars it was probably not a statistically significant trend. Either way, he is still relying heavily on the Lyman paper.]
Regarding ocean heat content, RP Sr. wants to use it a replacement for the surface temp indices, which is a bit more than just difficult (assuming one is interested in an index with some practical meaning).
On the role of CO2, since the ARs are a little thin on the discussion of mitigation policy, apparently what he means by this is that the people who run the IPCC distort its findings so that they can promote energy policy changes in other venues. I call that a straight-up conspiracy theory. He also ignores the fact that the larger part of the concern about CO2 is for the future, when its effects will become even more dominant.
Regarding the surface record, AFAICT he believes that corrections for all the biases he thinks exist (nocturnal boundary layer effect on minimum temps plus microsite effects) would shift it substantially in a warm direction, thus creating a conflict with the models.
[...] be interesting at all. The globe is warming, we would expect the oceans to warm as well. But Dr. Pielke has continually the Lyman ocean heat content paper to show that the oceans are cooling. [See the [...]