Last spring, Ottmar Edenhofer (newly elected co-chair of IPCC WGIII) and colleagues of the Potsdam Institute for Climate Impacts Research (PIK) wrote a letter to Nature responding to the Pielke, Wigley, and Green paper “Dangerous Assumptions” (PDF).  In it Edenhofer et al. made the claim:

Over the past 30 years, the decrease in energy intensity has been 1.1% a year — well above the 0.6% a year assumed in 75% of the energy scenarios assessed by the IPCC.

At the time I expressed some concern that the value of 0.6% didn’t make sense. When Edenhofer et al. repeated this number in a discussion paper that we mentioned earlier this week, I emailed Dr. Edenhofer to see if we could clarify the issue. I received a thoughtful email in response, and while Edenhofer et al. declined an invitation to participate in the blog discussion, I am happy to report that the dialogue has resulted in a consensus among us on the assumptions.

Specifically, the SRES scenarios shows a mean/median for energy intensity decline of just under 1.3% per year, and, further, 75% exceed ~1.1%, and no more than 10% are at or below 0.6%. Edenhofer et al. have agreed to correct their discussion paper, and I have asked that they also send a correction to Nature. We appreciate the correspondence.