How sustainable are public debt burdens?

Over the past few years, the governments of most advanced economies have made a lot of progress in repairing the damage caused to their public finances by the global financial crisis. The majority should not need to tighten fiscal policy much further in order to get their debt burdens back to pre-crisis levels. However, Japan and parts of the euro-zone are exceptions: prospects for reducing their debt ratios remain uncertain and much greater austerity will probably be needed.