Ian Ayres "Give Freakonomics a Chance".

Robert Hahn and Peter Passell "Time to Change U.S. Climate Policy".

Aaron S. Edlin "A Christmas Warning".

Steffen Kallbekken and Torben K. Mideksa "Letter: Why Urgent Emissions Reductions are Needed". 

Adrian E. Tschoegl "Letter: Observation, Theory-Building, and Theory-Testing".