WASHINGTON —An important point in Alan Greenspan's much-hyped memoir has gone largely unnoticed: He acknowledges that global economic forces, more than Federal Reserve policy, kept inflation low and manageable for two decades.

By global forces he means free trade, the rise of emerging, cheap-labor economies led by China and India and the benefits from information technology and the Internet.

He warns that these forces — "globalization," in shorthand — are weakening as they mature. He fears that could mean a gradual return to persistent 1970s-style inflation over the next 20 years or so. And he worries that could cripple a U.S. economy that's already facing strains from the graying of the population over the same period.

Not everyone agrees.

"I do think he's overly pessimistic. Which is not to say things he's pointing to aren't real or potentially real," said Alan Blinder, a former Fed vice chairman and Princeton University economist who thinks that U.S. and European policymakers are unlikely to let inflation get out of hand because they learned hard lessons in the '70s.

Inflation measures the rise of prices across the economy over time. It's relatively stable at the moment: Consumer prices rose only 2 percent over the 12 months through August. But oil prices are high — more than $80 a barrel — commodities from corn to gold are flirting with records and Americans are increasingly fearful that free trade is hurting wages and workers at home, and may restrain it.

All those factors threaten to boost inflation.

It roared out of control from the late 1960s through 1981. Prices rose so quickly that they eroded the purchasing power of a dollar. In 1979, $100 on Jan. 1 was worth $87 by Dec. 31.

To avoid that erosion of their wealth, '70s investors moved money out of stocks and bonds into nonproductive assets such as gold and art. The economy shrank four years out of the nine from 1974 to 1982. Living standards fell.

And interest rates soared. To ensure profit on eroding money, lenders charged higher interest and investors demanded higher yields. That made car loans, college tuition and credit card debt more costly to finance.

Mortgage rates rose too, making it harder to finance home purchases and putting downward pressure on home prices. A $200,000 fixed-rate 30-year mortgage with a 6 percent interest rate carries a monthly payment of $1199.10. If inflation pushes the mortgage rate to 10 percent, that mortgage costs $1755.14 per month, almost half again as much.

Greenspan, the leading economic seer of the roaring 1990s, fears that the table's being set for it all to happen again.

The biggest reason is that "having largely bestowed its benefits, globalization will slow its pace," he wrote.

For several decades, the benefits of globalization — primarily abundant foreign-made goods produced for low wages and purchased for low prices &mash; helped hold down U.S. inflation. But that's changing.

China, for example, the biggest source of U.S. imported goods, has a growing inflation problem. Its inflation rate hit an 11-year high of 6.5 percent in August.

Wages in China grew 13.5 percent last year. As Chinese workers demand higher pay to cover rising prices, production costs rise. Eventually, the price of Chinese-made goods purchased by Americans will rise as well.

Just as inexpensive imports helped hold down inflation here the past two decades, inflation here will rise with import prices. How much, how fast? While U.S. inflation rates varied greatly over the years, on average from 1939 through 1989 consumer prices rose by 4.5 percent per year.

"That's probably not a bad first approximation of what we will face," Greenspan warns in his book "The Age of Turbulence." An annual inflation rate of 4.5 percent would reduce the purchasing power of $10,000 to $6,439 in one decade, according to the Tax Policy Center, run by the Urban Institute and the Brookings Institution.

Greenspan says the threat of rising inflation is already here. He told CBS's "60 Minutes" that his successor, Ben S. Bernanke, faces a different economic chessboard from the one he had in the '90s.

"We were dealing with an environment back there where inflation was easing. We could have acted without the fear of stoking inflationary pressures. You can't do that anymore," Greenspan said.

Mainstream economists agree.

"I don't think inflation is an imminent danger, but I do agree with him that he had a very favorable environment . . . and I don't think Bernanke is going to have the same luck," said David Wyss, chief economist for Standard & Poor's, a financial-research firm.

Bernanke's Fed said rising inflation was the biggest threat to the economy as recently as Aug. 7. Then a gathering credit crisis rooted in the housing sector's problems led the Fed to switch priorities and slash interest rates by half a percentage point this month to avoid recession.

Some analysts fear that only poured fuel on the glowing embers of incipient inflation, and may come back to haunt Bernanke, perhaps as soon as next year.

Greenspan, too, thinks that future Fed chairmen will need to raise interest rates to keep a lid on inflation — the Fed's primary mission — but he fears that the emerging populist political environment, as reflected in Democrats' rising opposition to free trade, may not allow it. He fears that the Fed could be forced into accepting higher inflation.

In response to soaring double-digit inflation, Greenspan's predecessor Paul Volcker raised interest rates even higher beginning in 1979, deliberately forcing a recession in 1981-82. Volcker's move was unpopular. At its peak the banks' prime lending rate — the one they charge their best borrowers — stood at 21.5 percent. Few could afford loans. But when the economy emerged from recession in 1982, inflation was effectively crushed.

The 1980 inflation rate of 12.5 percent fell to 3.8 percent in 1982. It's been modest ever since, averaging 3.24 percent from 1982 to 2006.

The era of low stable inflation coincided with the greatest sustained burst of economic expansion in world history. The U.S. economy has shrunk in only 16 months of the 25 years since the 1982 recession ended. That's convinced economists that low inflation provides an essential foundation to permit sustained economic growth. Blinder, the former Fed vice chairman, thinks the lesson won't soon be forgotten.

He argues that globalization is still dynamic and foreign competition will remain a check on U.S. prices.

"I think he (Greenspan) underestimates how much of the China and India phenomenon is still in the future, not in the past," Blinder said. "When it comes to India and services, I think we've barely scratched the surface. I think there's a huge downward pressure on a variety of services prices . . . to come for many years. And services are a much bigger portion of the consumer's basket than goods."

While that trend would keep a lid on many U.S. wages, it also would help contain inflation here.