Torturously slow recoveries from recessions and low inflation are here to stay unless policymakers can get a better grip on how to stabilize the global economy in an era of lower interest rates, New York Fed President John Williams said.

Lower birthrates are keeping population growth down in the world's wealthier economies and technological advancement has shifted down to more normal levels. Each trend is capping how much economies can grow, Williams said.

Williams, who earlier in his career was a researcher at the San Francisco Fed, is known for helping develop estimates of what the "neutral" interest rate might be. Now, he is pushing to encode some of that thinking in how the Fed approaches inflation from now on.

As part of a broad policy review, Williams has been advocating for the Fed to systematically respond to periods of tepid inflation by keeping U.S. interest rates "lower for longer."