Outgoing Federal Reserve Chairman Alan Greenspan warned Friday that America’s exploding budget deficit and a protectionist backlash against soaring trade deficits could disrupt the global economy.

On a day when he was being honored in London for his nearly two decades in the world’s highest profile economic job, Greenspan restated some familiar worries.

He said U.S. deficits are set to soar with the pending retirement of 78 million baby boomers and he suggested that Congress consider trimming Social Security and Medicare benefits because the government probably has promised more than it can afford, especially in health benefits.

If something isn’t done to trim benefit costs, he said, the resulting budget deficits would “cast an ever-larger shadow” over the future living standards of Americans.

Greenspan repeated his belief that the country’s record trade deficits can be addressed through market forces without any harm to the economy.