1683 DeCeMber 2011 AMerICAN MeTeOrOLOGICAL SOCIeTY | DOI: 10.1175/BAMS-D-11-00191.1 C urry and Webster (2011) discuss the important topic of uncertainty in climate research. While we agree that it is very important that uncertainty is estimated and communicated appropriately, their discussion of the treatment of uncertainty in the IPCC assessment reports regarding attribution is inaccurate in a number of important respects. IPCC has placed high priority on communicating uncertainty (Moss and Schneider 2000; Mastrandrea et al. 2010, 2011). Since detection of climate change and attribution of causes deals with distinguishing “signals” or “fingerprints” of climate change from climate variability, an approach requiring substantial use of statistics (see Hegerl et al. 2007), this area of research has always placed high priority on estimating uncertainties appropriately. Hence the chapter on attributing causes to climate change of IPCC AR4 (Hegerl et al. 2007) discusses the uncertainty in its findings in detail, including in an overview table where remaining uncertainties are explicitly listed for each finding. In this brief comment we will limit our focus to the four key errors and misunderstandings in Curry and Webster (2011) regarding the treatment of uncertainty in the detection and attribution chapter of IPCC AR4: