The History Manifesto is new book from Jo Guldi and David Armitage that argues historians need to shift back to longer-term narrative history. This may help historians recapture the prestige and influence that allowed them to help shape public policy. The shift to microhistories (writing about time periods of 30 years or less) has limited historians influence. Guldi and Armitage believe that the shift to longer narrative histories will encourage policy makers to take a longer approach to issues relating to human rights and the environment. The authors want the entire history profession to shift to long term thinking.
Guldi and Armitage make a fascinating argument. Additionally, new digital analytical tools will make it easier for historians to research and write about longer periods of time. Whether or not this shift would increase the prestige and influence of historians is debatable. There are a number of reviews about The HIstory Manifesto online. Scott McLemee has a brief review of their book at Inside Higher Ed.
Here is a short interview with the authors where they describe their project.