China und die USA: das seltsame Gespann hat bisher die Weltwirtschaft vorangetrieben, doch beide Seiten schwächeln, schreibt der Economist: Over the past year the world economy has grown by almost 5%, its fastest pace in two decades. Growth has been powered by two high-octane fuels: America's exceptionally loose monetary policy, which has encouraged consumers to keep spending; and an unprecedented investment boom in China. America and China together accounted for almost half of global growth over the past year. If American consumers and Chinese producers were to retreat at the same time, global growth could slump. ... But inflation is now rising, so monetary policy needs to be tightened. How will the American economy—indeed, the world economy—fare if interest rates return to more normal levels of perhaps 4-5%? Super-low rates have encouraged consumer behaviour that will look a lot less sensible as interest rates rise. And to make things trickier, crude-oil prices have surged to new heights at the very time that the Fed has started to raise rates. Dearer money and dearer oil have already caused consumers to cut back. China's breakneck pace of growth also looks unsustainable. In the year to the second quarter its GDP grew by almost 10%. Real fixed investment was increasing at an annual rate of 35% earlier this year; bank lending has been rising too fast, fuelling a property bubble; and inflation has moved above 5%. If China suffers a hard landing, the rest of the world will feel the bump: in the past three years, the country has contributed one-third of the world's growth in real output, measured at purchasing-power parity