In a Bloomberg View op-ed, Carmen Reinhart and Kenneth Rogoff explain why now is a bad time for the government to borrow, even though interest rates are low:
Several studies of financial crises show that interest rates seldom indicate problems long in advance. In fact, we should probably be particularly concerned today because a growing share of advanced country debt is held by official creditors whose current willingness to forego short-term returns doesn’t guarantee there will be a captive audience for debt in perpetuity.
Those who would point to low servicing costs should remember that market interest rates can change like the weather. Debt levels, by contrast, can’t be brought down quickly. Even though politicians everywhere like to argue that their country will expand its way out of debt, our historical research suggests that growth alone is rarely enough to achieve that with the debt levels we are experiencing today.
While we expect to see more than one member of the Organization for Economic Cooperation and Development default or restructure their debt before the European crisis is resolved, that isn’t the greatest threat to most advanced economies. The biggest risk is that debt will accumulate until the overhang weighs on growth.
Reinhart and Rogoff authored a study and book establishing a 90 percent level of public debt to GDP as a dangerous threshold. That number is now constantly used on Capitol Hill in discussions about the debt.