Climatologist James Hansen was originally scheduled to deliver a keynote address at the American Geophysical Union's meeting in San Francisco on Tues., Dec. 10, but at very much the last moment it was postponed until Weds., Dec. 11. I was a continent away, but thanks to the standing-room only crowd that attended, many of whom were tweeting, it was easy to follow the thread of Hansen's speech.
Most of his remarks echoed messages in the recent PLOS ONE paper "Assessing 'Dangerous Climate Change': Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature" (doi:10.1371/journal.pone.0081648
), for which he is the lead author. I reviewed the content of that paper for Scientific American
and also discussed them with Hansen in a Q&A
on my Gleaming Retort blog for PLOS Blogs. Other links in my coverage of the report can be found here
One detail that Hansen discussed in his keynote but that did not come up in his discussion with me was that he and his coauthors first submitted the report to Proceedings of the National Academy of Sciences, but withdrew the paper when its editors objected to "normative statements" about the implications of the scientific findings, which may have been seen as prescribing policy. No doubt that revelation will be fodder for further discussion in some precincts of the Web about the appropriateness of scientists airing views on policy....