There has also been a savings-investment imbalance beyond that explained by the fall in productivity growth, often referred to as a “global savings glut”. In part, this is explained by the ageing populations of advanced countries, driving up the demand for safe assets at a time when they have become increasingly scarce. This falling real rate is bad news for savers since it means lower future returns in terms of consumption of additional goods and services. And in the long run it is the concept of the natural rate that determines the return to saving, not short-term movements in monetary policy. 1/5  BIS central bankers' speeches  This concept of a natural rate of interest represents the real rate consistent with saving and investment being in balance, output being at its potential and neither upward nor downward pressure on inflation. While the natural rate may change over time, it is unobserved and can only be estimated. Such estimation is relatively imprecise, with different models giving a range of estimates making it uncertain as to the true level of the natural rate.1 Nonetheless, the natural rate does appear to be lower than in the past.2  Why unconventional measures have been necessary Developments in the natural rate matter for the conduct of monetary policy in the euro area. To stimulate the economy, central banks steer short-term real interest rates below the natural rate to encourage the public to bring forward spending, be it in the form of consumption or investment.

Youth unemployment fell to 20.6% in the third quarter and continues to decline more rapidly than the overall unemployment rate. Bank lending to households and companies is growing, while demand for loans is rising. ECB simulations showed that euro area GDP would be cumulatively at least 1.5% lower between 2015 and 2018 without the expansionary policy measures, with worse outcomes for inflation. And more than that: by acting timely and decisively we preserved future growth prospects. There is a growing awareness of the potential permanent negative effects of prolonged downturns, a process termed hysteresis. There are a number of channels through which hysteresis works. Unemployed people lose valuable human capital and skills that may take time to recover. They may also become permanently discouraged from working, reducing long-run participation in the labour force. The distressingly high rates of youth unemployment witnessed in many euro area economies are likely to cause some labour market “scarring”. Prolonged downturns may also cause businesses to become increasingly uncertain about future prospects, causing them to delay investment. This has the dual effect of depressing current economic activity, which reinforces the downturn, and reducing the amount of capital available for future production. Lower future growth translates directly into lower natural rates today, something I shall return to shortly. 2/5  BIS central bankers' speeches  Other potential consequences of unconventional measures While our measures have been successful in their aim of stabilising output and inflation, they also carry risks in terms of allocation of resources and distribution of wealth and income.