Andrew Dessler adds a helpful coda to his comments in my newspaper story of a couple of weeks back:
I agree with Pielke Sr. that assessments have to include the range of opinions held by the majority of the scientific community. If half of the community says one thing and the other half says something else, then a good assessment will include both views. My sense is that the recent AGU assessment on hurricanes failed in this regard (see also this Prometheus post).
However, we have to be careful about including views that are “too diverse.” The goal of a scientific assessment is to let policymakers know what the scientific community thinks on an issue. If 99.9% of the scientists think one thing (e.g., the Earth is warming), then should the assessment include a dissenting view held by 0.1% of the community? I would argue not. Policymakers are often unable to discern a 99.9% position from a 0.1% position, and they look to expert assessments to do just that. If they don’t, then the assessment has essentially abdicated its responsibility to clarify the science for the policymakers.