Afinancial crisis in China has become inevitable. If it happens soon, its effects can be contained. But, if policy makers use further doses of stimulus to postpone the day of reckoning, a severe collapse will become unavoidable within a few years.

The country is in the middle of by far the largest monetary expansion in history. On one widely used measure, M2, its money supply has tripled in the past six years, an expansion four times as large as that of the US over the same period.

This unprecedented expansion is at least partly responsible for China’s extraordinary growth rate, which is now running up against a demographic constraint. Last year, for the first time, the working-age population declined, a trend set to continue for the next two decades. Unless the country can keep lifting the labour force participation rate (for example by getting more women into the workforce or persuading older people not to retire), China will struggle to expand its labour force by even 1 per cent per year. To sustain economic growth of more than 7 per cent, productivity would need to grow by 6-7 per cent a year across the entire economy. This would be a tall order in any country. In China, where the labour-intensive services and agriculture sectors make up half the economy, it is well-nigh impossible.