Whether this is merely a cyclical blip or the start of a longer secular slowdown is unclear. Michael Pettis at the University of Peking believes that Chinese growth might permanently slow to around 4 per cent a year - half the rate of recent years. And the middle income trap warns us that growth can stall for a long time in poorer economies.
Whichever it is, investors should think about the possible implications of this shift in the global economy.
You might think the obvious one is simply that emerging markets become less attractive as an asset class. But this is not obvious, Across countries, there's no correlation between medium-term growth and equity returns. Granted, emerging markets face risks. But it's possible that the danger of an (eventual) tightening of US monetary policy is a bigger one than a moderation in domestic growth.
Instead, there are other implications for investors. Here are five of them.
First, government bond yields could rise. This would be the normal result of economic growth in the west, as this would encourage investors to shift from safe assets into riskier ones - a process that might be exacerbated by central banks reducing or eventually reversing quantitative easing. It could also, though, be an effect of the Chinese slowdown. Such slower growth - especially to the extent that it's accompanied by a decline in the savings ratio as the economy rebalances towards consumer spending - would tend to reduce the growth of the country's savings. And this in turn could reduce the global savings glut that has held bond yields down for most of this century.
Second, gold could fall. This would follow from a reduction in the growth of Chinese savings, as this would reduce the excess demand for safe assets that has contributed to the big rise in gold prices over the last 10 years. Also, though, anything that raises bond yields would tend to hurt gold. This is because when real yields on financial assets are higher, gold becomes less attractive simply because the opportunity cost of holding it - the yield you forego on other assets - is higher.
Third, miners' derating is justified. The FTSE mining sector now has a higher dividend yield and lower price-earnings ratio than the general market - a sign that investors believe the sector's growth prospects have deteriorated. This is consistent with the idea that slower emerging markets growth means slower growth in demand for commodities.
Fourth, don't bet on inflation falling much. We're not talking here about a collapse in demand for commodities - unless something surprising happens - but merely a slower increase in demand for them. This isn't enough in itself to cause big falls in raw materials' prices. And the fact that real wages are likely to continue rising in emerging markets means that the days of a dirt cheap 'China price' are gone.
Fifth, bubbles might become less likely. It's tempting to think that if commodity stocks have gone ex-growth, then speculative money will flow into something else. Don't be so sure.
For one thing, one of the fundamental problems with western economies - the dearth of profitable investment opportunities - won't disappear quickly. This kicks away one traditional support for bubbles - the ability to tell a story about coming massive growth in a sector.
Also, one reason for the bubbles of the mid-2000s - in housing, credit and perhaps bonds and gold - was precisely that Asian economies were putting a glut of cheap money into the west which could not be invested productively. If the savings glut diminishes and bond yields rise, this problem will fade away.
In this sense - perhaps paradoxically - slower growth in emerging markets might contribute to financial stability in the west.
