That claim went unchallenged during the normal, multistep review process used by the IPCC. The error wasn’t widely noticed until last November, when a group of scientists began discussing a new study of the Himalayan glaciers. The discussion led Cogley to look up the original sources for the claims in the IPCC report. He found two sources, a news report in the London-based magazine New Scientist about an as-yet unpublished study, and an article that estimated the glaciers could shrink to one-fifth their current area by 2350, rather than 2035, putting the IPCC report off by about 300 years. His finding is described in a letter to the editor to be published January 29 in the journal Science. Field confirms that the New Scientist was one of the sources, but not the report giving the date of 2350.
David Victor, the director of the Laboratory on International Law and Regulation at the University of California, San Diego, says that the error should not lead to a major change in the IPCC’s process. “A very small fraction of IPCC reports stems from grey literature,” and an outright ban on such sources would be a bad idea, since it would prevent the organization from drawing on certain types of valuable information. For example, government reports, or even raw data on greenhouse gas levels or measurements of the extent of glaciers, are often not a part of peer-reviewed literature.
Cogley recommends two main changes. First, all sources cited should be readily available to reviewers, which would have made it easier to see that the source for the 2035 date was a news report. (The IPCC report does not cite the New Scientist, but rather another document, which in turn cited the New Scientist.) Second, he says, researchers working on different parts of the IPCC report should work together more closely. Kaser says that if during the normal review process even one glaciologist of the many who worked on the Working Group I report (“The Physical Science Basis”) would have carefully read the Working Group II report, the error would have been caught.