Professor Holdren gave an incredibly stark, complex, and truly amazing presentation. I won’t do it a disservice by boiling it down to a paragraph here. (I’ll publish the full text when it becomes available online). The one fact that shocked me: We previously thought that Arctic sea ice would be completely gone by 2050 if we failed to act. It now looks like it will be gone by 2013…FIVE years from now. He says, “We are already experiencing dangerous consequences of human interference in the climate system. The only question is whether that will be catastrophic.” He also mentions the Sigma Xi-UN Foundation report, which he led and would give you a pretty good view of what he’s presenting on now.