By "we" do you mean your family, your city, your nation, Europe, your continent, your terrestrial hemisphere, the whole planet, the solar system, or what else?
As for me, I already live in an austere way:
Of course, austerity measures mostly affect the ones who consume the least to begin with, so its not a solution anyway, its mostly a joke in that regard
About austerity? Just accepting it. You already know how I feel about it. You have to see the positive side of things. It will be a good exercise in patience, discipline, simplicity, humility. To appreciate what really matters.
To answer it would take a whole book and a lot of patience....
To simplify let us say that ambition drives some to enrich themselves, seek power and lead others; necessity and humility drives others to obey, submit and settle for security and protection: I am among those.
As for me, I already live in an austere way: