ALAN GREENSPAN: U.S. May Soon Reach Borrowing Limit.

Former Federal Reserve Chairman Alan Greenspan said the U.S. may soon face higher borrowing costs on its swelling debt and called for a “tectonic shift” in fiscal policy to contain borrowing.

“Perceptions of a large U.S. borrowing capacity are misleading,” and current long-term bond yields are masking America’s debt challenge, Greenspan wrote in an opinion piece posted on the Wall Street Journal’s website. “Long-term rate increases can emerge with unexpected suddenness,” such as the 4 percentage point surge over four months in 1979-80, he said.

Indeed. Related: Gold hits record high.