The International Ad Hoc Detection and Attribution Group (IDAG) is a self-organized group of climate experts interested in the problem of the detection and attribution of externally forcing climate signals in the observations. This report, like our others, expresses our collective views and not those of any international or national agency. While most of the Group obtains funding from their normal sources, we wish to acknowledge the Climate Change Detection and Attribution Project, a jointly funded effort by NOAA’s Office of Global Programs and the Department of Energy’s Office of Science, for providing support for meeting and specialized studies of the Group members. PAS was funded by the U.K. Department for Environment, Food and Rural Affairs under contract PECD 7/12/37. GH was also funded by NSF grant ATM-0296007. We also thank Karen King of DOE’s Pacific Northwest National Laboratory for handing the Group’s administrative matters and Jesse Kenyon for help with the manuscript.
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