Comment On Tom Karl’s Interview In The Washington Post

There is an interview of Tom Karl, Director of the National Climate Data Center titled Global warming: What the science tells us. His responses repeat his advocacy position that he has presented in other venues.

However, I want to highlight what one of his answers which is quite a dishonest response.

The question and answer are

Silver Spring, Md.: Hello,

“Many people imply that the CRU temperature data are the exclusive or principal basis for climate change predictions. Please identify some key studies that do not rely heavily on CRU data, and their conclusions. Thanks.”

Thomas R. Karl: Hi there – thanks for the question. In fact, there are other global temperature datasets that are calculated by other institutions. For example, NASA calculates an independent global temperature dataset, as does NOAA (here at National Climatic Data Center). The analysis techniques for each of these datasets are all independent of each other and yet they all come to the same conclusion: that global warming is unequivocal….”

This is a dishonest answer and Tom Karl knows it. The NASA data set and the CRU data sets are not independent of the NCDC data set.

I have discussed the interdependence of the data sets in recent posts (e.g. see and see ).

Tom Karl has  even conveniently ignored the text from the CCSP 1.1. report [of which Tom Karl was the Chief Editor!];  i.e.

In the report “Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences Final Report, Synthesis and Assessment Product 1.1” on page 32 it is written

“The global surface air temperature data sets used in this report are to a large extent based on data readily exchanged internationally, e.g., through CLIMAT reports and the WMO publication Monthly Climatic Data for the World. Commercial and other considerations prevent a fuller exchange, though the United States may be better represented than many other areas. In this report, we present three global surface climate records, created from available data by NASA Goddard Institute for Space Studies [GISS], NOAA National Climatic Data Center [NCDC], and the cooperative project of the U.K. Hadley Centre and the Climate Research Unit [CRU]of the University of East Anglia (HadCRUT2v).”

These three analyses are led by Tom Karl (NCDC), Jim Hansen (GISS) and Phil Jones (CRU).

The differences between the three global surface temperatures  that occur are a result of the analysis methodology as used by each of the three groups…… This is further explained on page  48 of the CCSP report where it is written with respect to the surface temperature data (as well as the other temperature data sets) that

“The data sets are distinguished from one another by differences in the details of their construction.”

On page 50 it is written

“Currently, there are three main groups creating global analyses of surface temperature (see Table 3.1), differing in the choice of available data that are utilized as well as the manner in which these data are synthesized.”


“Since the three chosen data sets utilize many of the same raw observations, there is a degree of interdependence.”

The chapter then states on page 51 that

“While there are fundamental differences in the methodology used to create the surface data sets, the differing techniques with the same data produce almost the same results (Vose et al., 2005a). The small differences in deductions about climate change derived from the surface data sets are likely to be due mostly to differences in construction methodology and global averaging procedures.”

and thus, to no surprise,  it is concluded that

“Examination of the three global surface temperature anomaly time series (TS) from 1958 to the present shown in Figure 3.1 reveals that the three time series have a very high level of agreement.”

There are also other major unresolved issues with the surface data sets of NCDC, NASA and CRU which Tom Karl continues to ignore; e.g. see

 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


Recommended Reading Of An Article By Joe D’Aleo On The Lack Of Quality Of The Long Term Surface Temperature Trend Data Set Over Land

Tom Karl has a serious conflict of interest, as I have documented in these posts

Do The CRU E-Mails Provide Further Documentation Of A Conflict Of Interest In The Preparation Of A CCSP Climate Assessment Report?

E-mail Documentation Of The Successful Attempt By Thomas Karl Director Of the U.S. National Climate Data Center To Suppress Biases and Uncertainties In the Assessment Surface Temperature Trends

He also keeps showing his lack of knowledge of climate science; e.g. see

Erroneous Climate Science Statement By Tom Karl, Director Of The National Climate Data Center And President Of The American Meteorological Society

Tom Karl has clearly demonstrated that he is an advocate and is presenting  erroneous information on the robustness of the surface temperature data record as a metric to assess multi-decadal surface temperature trends. We need a new Director of the National Climate Data Center who will provide policymakers with an accurate balanced monitoring of the climate system.

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