As the assembled G20 world leaders take a break from negotiations at the ExCel centre today - maybe have a few drinks, regard the lovely vistas of the Thames, and wonder to themselves how they can be as cool as Barack Obama - perhaps the words "Yes You Can" fluttering by at 45 mph will remind them that sorting out the global financial system to make it more equitable and sustainable is not some impossible dream, it's the only thing that's going to actually work.
That's because it's not only the economy which is in trouble, the climate is facing its own ecological-credit crunch. There's not much point fixing the finance system if we're going to ignore the climate crunch that threatens much bigger problems for the world.