Reply By Pielke Et Al To The Comment By Parker Et Al. On Our 2007 JGR paper “Unresolved Issues With The Assessment Of Multi-Decadal Global Land Surface Temperature Trends”

In 2007, we published the paper

Pielke Sr., R.A., C. Davey, D. Niyogi, S. Fall, J. Steinweg-Woods, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, R. Mahmood, S. Foster, R.T. McNider, and P. Blanken, 2007: Unresolved issues with the assessment of multi-decadal global land surface temperature trends. J. Geophys. Res., 112, D24S08, doi:10.1029/2006JD008229.

The is a Comment by Parker et al in press in JGR-Atmospheres on our 2007 paper. It is

Parker, D. E., P. Jones, T. C. Peterson, and J. Kennedy (2009), Comment on ‘Unresolved Issues with the Assessment of Multi-Decadal Global Land Surface Temperature Trends’ by Roger A. Pielke, Sr. et al., J. Geophys. Res., doi:10.1029/2008JD010450, in press.

Their conclusion reads

 “Prompted by Pielke et al. [2007]’s concerns, we have provided an additional
demonstration of the robustness of global and hemispheric land surface air
temperature series. We have shown that Pielke et al [ 2007]’s attribution of changed
temperature trends to local LULC changes is not firmly based. We nevertheless
agree with Pielke et al. [2007] in aspirations for an improved global network
monitoring all Global Climate Observing System (GCOS) Essential Climate Variables
including humidity as well as temperature; for universal adherence to the GCOS
Climate Monitoring Principles
( which
include the availability of full metadata such as photographic documentation; and for
as well as the rescue and digitization of all historical data.”

Our Reply is also in press. It is

Pielke Sr., R. A., C. A. Davey, D. Niyogi, S. Fall, J. Steinweg-Woods, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, R. Mahmood, S. Foster, R. T. McNider, and P. Blanken (2009), Reply to comment by David E. Parker, Phil Jones, Thomas C. Peterson, and John Kennedy on ‘Unresolved Issues with the Assessment of Multi-Decadal Global Land Surface Temperature Trends’ . J. Geophys. Res., doi:10.1029/2008JD010938, in press. [the AGU on-line version is at].

Our conclusion reads

“We welcome a critical examination and further analysis of each of the arguments and findings in Pielke et al. [2007a]. Indeed, we are continuing this further assessment; e.g., see Lin et al. [2007]. However, the analyses performed by Parker et al. [2008] do little to improve confidence in the global surface temperature record. In particular, we reaffirm the statement in Pielke et al. [2007a] that nearby changes in LULC may be influencing the temperature trends observed at surface climate observing stations. We further continue to emphasize the lack of data independence in the global surface temperature analyses [including that of Parker et al. 2008]. We do agree with Parker et al. [2008] that data sparseness makes temperature trend estimates less robust over many parts of the globe, and join their call for improved data collection, metadata, and data rescue.”

It is useful also to see the Reviewers’s assessment of the Comment and Reply. This information is reproduced below.

 Reviewer Comments

Reviewer #1 (Comments):

Comments on the m/s, “Reply to comment by Parker et al., on “Unresolved Issues with the Assessment of Multi-Decadal Global Land surface Temperature Trends” by Pielke et al.

Parker et al. [2008] has raised two issues with the analysis of Pielke et al. [2008] on the surface temperature trends utilizing climate data records. In response to that criticism, the authors has dwelled on the details on how Pielke et al. [2008] conducted their analysis and arrived at their conclusions on two major aspects of their analysis. Also, the authors argue how and why Parker et al. comments are biased and present examples from the literature in support of their arguements.

 On the first issue, the authors provide a detailed response and show that one needs to follow a rigorous and standardized methodology in performing analyses as conclusions obtained from such analyses critically depend on such data processing methodologies. Based on the arguments presented by the authors, I do believe Parker et al. [2008] was incorrect in raising the issue of the degree of dependence in the analyses presented by Pielke et al. [2008].

In regards to SST trends that was presented by Parker et al. [2008], the authors provide very convincing arguments and cite several reported trends that were documented in the literature. As stated by the authors, I personally agree that it is difficult to extend the findings of temperature trends over land to that of ocean or vice versa. At the outset, on the second issue about LULC effects on the surface temperature trends, I stand by the authors’ statement that the near-by land-use changes impact the surface temperature trends.

I believe that this process of “fact finding” will eventually lead to the documentation of pros and cons of following a particular methodology, biases in such a methodology, and ultimately helps to standardize various aspects of data processing (e.g., homogenization). Finally, the outcome from these series of exchanges will solidify the confidence levels in such analyses and also provide standardized guidance to the climate data analysis community.

Reviewer #1 (Highlight):

This m/s is a part of ongoing scientific exchanges between the author and a scientist who was critical about the original works presented by the authors. At the end of this series of exchanges, I believe the outcome will shed light on the correct way of processing and analyzing global climate data records and interpretation of surface temperature trends.
Reviewer #2 (Comments):

“Reply to “Comment” by David E. Parker et al….”

By Pielke, Sr. et al. (hereafter “Reply”)

My remarks are below. Overall, this response is a reasonable reply to Parker et al. 2008 but I would recommend my four remarks be dealt with in the Reply.

Ln 62ff. The Reply deals here with only US station records while the Comment deals with global analyses. The real independence issue is with HadCRU (i.e. global) as described in Brohan et al. I suspect that few of the 82% remaining un-adjusted stations would have been adjusted prior to arriving at CRU though the Reply offers the assertion that the number is “possibly very large”. My understanding is that the raw data used by CRU does not have adjustments applied prior to its receipt at the Hadley Centre from whence it is sent to CRU for compilation. What evidence does the Reply offer to back up the assertion? (An email to P. Jones would answer this.)

Ln 107ff The Reply is correct that neither of the two Vose et al. 2005 papers looked at Lugina et al.’s dataset as claimed by the Comment (I missed that in my earlier review). As I understand it Lugina et al. is a dataset of near-surface land temperatures only. It has never achieved a notable level of acceptance in surface temperature analyses and certainly is not independent from the other datasets in terms of source data. In my experience in major assessments where this dataset was discussed I recall that questionable practices were used. If I remember correctly, one of the procedures was to relax toward climatology (i.e. zero anomaly) for missing regions – so that the magnitude of trends would indeed be reduced even on large scales (this was true of the upper air data sets from Russia). I don’t recall a substantial publication published which clearly documented all of the construction procedures. I must add, however, perhaps the assumptions applied in Lugina et al. may actually produce more accurate trends (I can’t say one way or another.) If Lugina used the practice of relaxing toward climatology for missing areas, this should be noted as a reason for the discrepancy.

Ln 116 what were the substantial differences between? Were there substantial differences in trends between closely located stations?

Ln 137ff The analysis of Compo and Sardeshmukh 2008 (Ocean Influences on Recent Continental Warming – CS08) suggests there is a strong connection between land and ocean temperatures regarding long-term trends. That the land responds with a larger magnitude is what would be expected according to CS08 (and in support of the Comment). While the Reply is correct in stating that different local surface temperature processes are involved, CS08 suggests the global circulation creates a situation where the oceans and continents are interdependent enough to support an observable connection as implied in the Comment. How does the Reply deal with CS08? (What is interesting is that CS08 admit the oceanic forcing could be almost entirely natural – and thus the land response would be as well.)

We are pleased that Parker et al engaged in this scientifically constructive debate. We need more such dialog within the climate community.


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