Dan Klein asked What Do Economists Contribute? Good question. Can applied economics affect the public policy discussion? Only if economists make it a point to address the "everyman".
Bjorn Lomborg (with support from The Economist) has assembled eight economist luminaries together in the Copenhagen Project to rank-order policy initiatives -- if $50 billion were available. The ranking puts disease control (HIV/AIDS), micronutrients (to limit malnutrition) trade liberalization and the control of malaria first. Global warming policies are all last.
Predictably, critics scorn the exercise as getting us involved in "either-or" choices. As they say: "Hello!"