In the news today, there is an erroneous statement by Phil Jones regarding the surface temperature data sets that are used to diagnose global warming
In Harrabin’s Notes: E-mail impact it is reported
“Professor Andrew Watson, a long-term colleague of the researchers at the CRU, said the unit should have nothing to fear from an inquiry, as the CRU temperature data set at the heart of many of the e-mails is almost identical to the two other authoritative data sets, both in the US.”
In an interview with the Guardian titled “Climate scientist at centre of leaked email row dismisses conspiracy claims” Phil Jones is quoted as staying
“….Our global temperature series tallies with those of other, completely independent, groups of scientists working for Nasa and the National Climate Data Centre in the United States, among others. Even if you were to ignore our findings, theirs show the same results. The facts speak for themselves; there is no need for anyone to manipulate them.”
These claims of that the surface temperature series are “completely independent” is false and Phil Jones knows that.
[UPDATE pm Nov 25 2009: I have been requested to word this more clearly, as Jones meant that the groups of scientists are completely independent, not that the series are independent. It is correct that the three groups completing the analyses work with different (independent) agencies. However, they do interact closely with each other so they are not "completely independent" even with this interpretation of what he meant. More significantly and what I interpreted from Jones's statement that "[e]ven if you were to ignore our findings, theirs show the same results” indicates to me that he is implying that their findings are independent confirmations of the CRU findings. They are not.
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. They are not “completely independent”. 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.”
Each of the three surface temperature analysis suffer from unresolved uncertainties and baises as we documented, for example, in our peer reviewed 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.
Perhaps Phil Jones was misquoted in the Guardian, and if he was, I would be glad to post his correction here on my weblog. If, however, he does not correct his documented erroneous statement to the media, it will only perpetuate the view that he is continuing to feed misleading information to the public and to policymakers.