The tumbling oil price is a warning of turbulent times in the world economy

Brent crude's fall lifts the pressure on central banks to curb inflation. But it also reflects a decline in economic optimism

After six weeks of falling, the oil price came to a pause last week. In the global ranking of economic events, a 20%-plus drop in the price of the black stuff is a big deal. A barrel of Brent crude cost $86 at the beginning of October. Last week the cost of a barrel fell to just $66 before settling at $67.

Of course, the Brent price is only back to where it was in March, and remains well above the low of $28 it hit in early 2016. Yet such a dramatic fall will force America's central bank to rip up its forecasts for inflation and reconsider some of its planned interest rate rises.