Reading CRU e-mails with CEI-colored glasses

From the CLIMATEGATE e-mails:

As I see it, there are two key issues here.

First, the Competitive Enterprise Institute (CEI) and Pat Michaels are arguing that Phil Jones and colleagues at the CRU [Climatic Research Unit at the University of East Anglia, UK ] willfully, intentionally, and suspiciously "destroyed" some of the raw surface temperature data used in the construction of the gridded surface temperature datasets.

Second, the CEI and Pat Michaels contend that the CRU surface temperature datasets provided the sole basis for IPCC "discernible human influence" conclusions.

Both of these arguments are incorrect. First, there was no intentional destruction of the primary source data. I am sure that, over 20 years ago, the CRU could not have foreseen that the raw station data might be the subject of legal proceedings by the CEI and Pat Michaels. Raw data were NOT secretly destroyed to avoid efforts by other scientists to replicate the CRU and Hadley Centre-based estimates of global-scale changes in near-surface temperature. In fact, a key point here is that other groups -- primarily at the NCDC [NOAA National Climatic Data Center] and at GISS [NASA Goddard Institute for Space Studies], but also in Russia -- WERE able to replicate the major findings of the CRU and UK Hadley Centre groups. The NCDC and GISS groups performed this replication completely independently. They made different choices in the complex process of choosing input data, adjusting raw station data for known inhomogeneities (such as urbanization effects, changes in instrumentation, site location, and observation time), and gridding procedures. NCDC and GISS-based estimates of global surface temperature changes are in good accord with the HadCRUT data results.

The second argument -- that "discernible human influence" findings are like a house of cards, resting solely on one observational dataset -- is also invalid. The IPCC Third Assessment Report (TAR) considers MULTIPLE observational estimates of global-scale near-surface temperature changes. It does not rely on HadCRUT data alone - as is immediately obvious from Figure 2.1b of the TAR, which shows CRU, NCDC, and GISS global-mean temperature changes.

As pointed out in numerous scientific assessments (e.g., the IPCC TAR and Fourth Assessment Reports, the U.S. Climate Change Science Program Synthesis and Assessment Report 1.1 (Temperature trends in the lower atmosphere: steps for understanding and reconciling differences), and the state of knowledge report, Global Climate Change Impacts on the United States, rigorous statistical fingerprint studies have now been performed with a whole range of climate variables -- and not with surface temperature only. Examples include variables like ocean heat content, atmospheric water vapor, surface specific humidity, continental river runoff, sea-level pressure patterns, stratospheric and tropospheric temperature, tropopause height, zonal-mean precipitation over land, and Arctic sea-ice extent. The bottom-line message from this body of work is that natural causes alone CANNOT plausibly explain the climate changes we have actually observed. The climate system is telling us an internally- and physically-consistent story. The integrity and reliability of this story does NOT rest on a single observational dataset, as Michaels and the CEI incorrectly claim.

I have known Phil for most of my scientific career. He is the antithesis of the secretive, "data destroying" character the CEI and Michaels are trying to portray to the outside world. Phil and Tom Wigley have devoted significant portions of their scientific careers to the construction of the land surface temperature component of the HadCRUT dataset. They have conducted this research in a very open and transparent manner -- examining sensitivities to different gridding algorithms, different ways of adjusting for urbanization effects, use of various subsets of data, different ways of dealing with changes in spatial coverage over time, etc. They have thoroughly and comprehensively documented all of their dataset construction choices. They have done a tremendous service to the scientific community -- and to the planet -- by making gridded surface temperature datasets available for scientific research. They deserve medals -- not the kind of deliberately misleading treatment they are receiving from Pat Michaels and the CEI.