Dr. John Holdren has been named as President-Elect Barack Obama's chief science advisor, in a move that will reassure scientists and anyone who gives a crap about the environment. A former head of the AAAS, he is known for speaking out rationally and calmly about climate change, and his appointment suggests that the issue is going to be taken extremely seriously by the Obama administration. To celebrate this news, here's a video of a lecture he delivered at Harvard in November 2007, titled "Global Climate Disruption: What Do We Know, What Should We Do?" For those of you who don't have a spare hour, you can also catch him in this clip from Letterman in April 2008. (HT: Island of Doubt)