I have a odd idea to improve diversity in the short run within the current system. Economists should create a convention (not rule) by setting the example that at least one of the reference letter writers should be female. I think this one small move could nudge people towards a big change. Young grad students will be more likely to work with women in a position of authority. Schools will try to find more senior level female economists for the department. And the young male colleagues might just behave a little better, if only to get a better working relationship and a reference from the female economist.