He borrows "George Monbiot’s lucid summary of John Maynard Keynes’ proposal":
Would have been a hell of a good idea. The whole problem with global economic adjustment is the asymmetry between surplus and deficit countries.
He proposed a global bank, which he called the International Clearing Union. The bank would issue its own currency – the bancor – which was exchangeable with national currencies at fixed rates of exchange. The bancor would become the unit of account between nations, which means it would be used to measure a country’s trade deficit or trade surplus.
Every country would have an overdraft facility in its bancor account at the International Clearing Union, equivalent to half the average value of its trade over a five-year period. To make the system work, the members of the union would need a powerful incentive to clear their bancor accounts by the end of the year: to end up with neither a trade deficit nor a trade surplus. But what would the incentive be?
Keynes proposed that any country racking up a large trade deficit (equating to more than half of its bancor overdraft allowance) would be charged interest on its account. It would also be obliged to reduce the value of its currency and to prevent the export of capital. But – and this was the key to his system – he insisted that the nations with a trade surplus would be subject to similar pressures. Any country with a bancor credit balance that was more than half the size of its overdraft facility would be charged interest, at a rate of 10%. It would also be obliged to increase the value of its currency and to permit the export of capital. If, by the end of the year, its credit balance exceeded the total value of its permitted overdraft, the surplus would be confiscated. The nations with a surplus would have a powerful incentive to get rid of it. In doing so, they would automatically clear other nations’ deficits.