As Abdalla El-Badri, secretary-general of Opec, noted with satisfaction over the weekend, the plunge in oil prices is already having a dramatic effect on the US shale industry.
Capital spending budgets are being cut back, drilling rigs idled and staff laid off. The remarkable growth of US oil production, which brought more than 1m barrels a day of additional supply on to world markets in each of the past three years, seems likely to flatten out this year.
Most of this pain is a consequence of market forces. The surge in output from the US, coming as global demand growth slowed sharply, has created excess supply. In the absence of any action from Saudi Arabia, which sees no reason to bail out its competitors, that oversupply can be corrected only through the price mechanism.