Gavin Schmidt, of the Goddard Institute for Space Studies and RealClimate.
I second this.
Also, Robert M. Hazen, origins of life researcher, educator, and author of the book Genesis. Interesting guy. After watching his teaching company course on the subject, I wrote a condensed abiogenesis primer for myself and other members of the fora I was posting on at the time (which you can find here
, in case anyone's interested). He was nice enough to answer a couple of questions.