Illustration by Kevin Kallaugher

RONALD REAGAN once described inflation as being “as violent as a mugger, as frightening as an armed robber and as deadly as a hit-man”. Until recently, central bankers thought that this thug had been locked up for life. Thanks to sound monetary policies, inflation worldwide had stayed low in recent years. But the mugger is back on the prowl.

Even though America is close to recession and growth in other developed economies has slowed, inflation is rising. Jean-Claude Trichet, president of the European Central Bank, this week gave warning about the mistakes of the 1970s, when inflation was let loose at huge cost to growth. His words were aimed at rich-country central banks, but policymakers in emerging economies are the ones who should most take heed. In countries such as China, India, Indonesia and Saudi Arabia even the often dodgy official statistics show prices have risen by 8-10% over the past year; in Russia the rate is over 14%; in Argentina the true figure is 23% and in Venezuela it is 29%. If you measure the numbers correctly, two-thirds of the world's population will probably suffer double-digit rates of inflation this summer (see article).

A 1970s reunion you really don't want to attend

Taken as a whole (and using official figures), the average world inflation rate has risen to 5.5%, its highest since 1999. The main cause has been the surge in the prices of food and oil, which briefly soared above $135 a barrel this week. But Mr Trichet's concern is that higher headline rates could push up inflation expectations, leading to bigger pay demands, and so trigger a wage-price spiral, as in the 1970s. Central bankers' mistake then was to hold monetary policy too loose, so that higher oil prices quickly fed into other prices. So it is worrying that global monetary policy is now at its loosest since the 1970s: the average world real interest rate is negative.

By slashing interest rates as inflation has climbed, has the Fed sowed the seeds of a new inflationary era? That case looks hard to prove in the rich world. Inflation rates of 3.9% in America and 3.3% in the euro area are far higher than central banks want, and inflation expectations are rising. If growth in the euro area remains robust, the ECB should certainly worry more about inflation. Yet so far there is little sign that higher food and oil prices are pushing up other prices in the rich economies. Wages have remained relatively subdued and core rates of inflation (excluding food and energy) are little higher than a year ago. Moreover, growth is expected to be below trend in America and Europe over the next year or so and unemployment is likely to climb, which will help to curb wage rises. America's consumer-confidence index has fallen to a 28-year low, which suggests that consumer spending will fall. This, in turn, will spur firms to cut costs and limit pay rises.

The picture is very different in emerging countries. Prices are rising much faster partly because food accounts for a bigger chunk of their consumer-price indices. But wages (rising at nearly 30% a year in Russia) and core-inflation rates are also accelerating. Many of these economies are operating close to full capacity, where inflation is more likely to take hold.

There are alarming similarities between emerging economies today and the rich world in the 1970s when the Great Inflation lifted off. Many policymakers in emerging markets view the rise in inflation as a short-term supply shock and so see little need to raise interest rates. Instead they are using price controls and subsidies to cap prices. Money supplies are growing almost three times as fast as in the developed world. Many central banks are still not fully independent. And inflationary expectations are not properly anchored, increasing the risk of a wage-price spiral. Emerging markets may as well be inviting the muggers into their own homes.

Watch your back

Rising inflation, like so much of the world economy in recent years, can be explained partly by the increasingly complex links between developed and emerging economies. Emerging economies shared some responsibility for America's housing and credit bubble. As Asian economies and Middle East oil exporters ran large current-account surpluses, they piled up foreign reserves (mostly in American Treasury securities) in order to prevent their currencies from rising. This pushed down bond yields. At the same time, cheap imports from China and elsewhere helped central banks in rich economies hold down inflation while keeping short-term interest rates lower than in the past. Cheap money fuelled America's bubble.

Now that this bubble has burst, the cross-border monetary stimulus has changed direction. As the Fed has cut interest rates, emerging economies that link their currencies to the dollar have been forced to run a looser monetary policy, even though their economies are overheating. Emerging economies with currencies most closely aligned to the dollar, notably in Asia and the Gulf, have seen the biggest price rises. Countries, such as Mexico, that have more flexible exchange rates and are more committed to inflation targets have done better.

Even if the Fed's interest rate suits the American economy, global interest rates are too low. In turn, the unwarranted stimulus to demand in emerging economies is further pushing up commodity prices; so too is speculative buying by investors seeking higher returns than from bond yields, which are still being depressed by the emerging economies' build-up of reserves. This stokes inflationary pressures in America and Europe and makes life difficult for rich-country central banks.

Loose money in America and rigid exchange rates in emerging economies are a perilous mix. The longer emerging economies hold down their exchange rates, the greater the risk of rising global inflation. Admittedly, exchange-rate appreciation is not as simple a remedy for emerging economies as some claim: a rise in interest rates and the expectation of a further appreciation in the exchange rate could, perversely, exacerbate inflation by sucking in more capital; and setting the exchange rate free risks massive overvaluation. But with an economic serial killer on the loose, one way or another monetary policy will have to tighten and exchange rates rise.