Climate scientists are refuting claims that raw data used in critical climate change reports has been destroyed, rendering the reports and policies based on those reports unreliable.
The Competitive Enterprise Institute, a free-market advocacy group, is arguing that U.S. EPA's climate policies rely on raw data that have been destroyed and are therefore unreliable. The nonprofit group -- a staunch critic of U.S. EPA's efforts to regulate greenhouse gases -- petitioned the agency last week to reopen the public comment period on its proposed "endangerment finding" because the data set had been lost (E&ENews PM, Oct. 9).
But climate scientists familiar with the data insist that the reports are based on sound science and that the data in question was altered as part of standard operating procedure to ensure consistency across reporting stations.
At issue is raw data from the Climatic Research Unit at the University of East Anglia in Norwich, England, including surface temperature averages from weather stations around the world. The data was used in assessments by the Intergovernmental Panel on Climate Change, reports that EPA has used in turn to formulate its climate policies.
Citing a statement on the research unit's Web site, CEI blasted the research unit for the "suspicious destruction of its original data." According to CRU's Web site, "Data storage availability in the 1980s meant that we were not able to keep the multiple sources for some sites, only the station series after adjustment for homogeneity issues. We, therefore, do not hold the original raw data but only the value-added (i.e. quality controlled and homogenized) data."
Phil Jones, director of the Climatic Research Unit, said that the vast majority of the station data was not altered at all, and the small amount that was changed was adjusted for consistency.
The research unit has deleted less than 5 percent of its original station data from its database because the stations had several discontinuities or were affected by urbanization trends, Jones said.
"When you're looking at climate data, you don't want stations that are showing urban warming trends," Jones said, "so we've taken them out." Most of the stations for which data was removed are located in areas where there were already dense monitoring networks, he added. "We rarely removed a station in a data-sparse region of the world."
Refuting CEI's claims of data-destruction, Jones said, "We haven't destroyed anything. The data is still there -- you can still get these stations from the [NOAA] National Climatic Data Center."
Tom Karl, director of the National Oceanic and Atmospheric Administration's National Climatic Data Center in Asheville, N.C., noted that the conclusions of the IPCC reports are based on several data sets in addition to the CRU, including data from NOAA, NASA and the United Kingdom Met Office. Each of those data sets basically show identical multi-decadal trends, Karl said.
Still, CEI's general counsel Sam Kazman remains skeptical of the IPCC's conclusions. The fact that the report relies on several data sets "doesn't really answer the issue," he said.
CEI and Cato Institute senior fellow Patrick Michaels argued that the "destruction of [CRU's] raw data violates basic scientific norms regarding reproducibility, which are especially important in climatology."
Ben Santer, a climate scientist at Lawrence Livermore National Laboratory, dismissed that argument. "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," he wrote in comments to the advocacy group Climate Science Watch.
Santer said CRU's major findings were replicated by other groups, including the NOAA climatic data center, the NASA Goddard Institute for Space Studies, and also in Russia.
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