Sean O'Grady: China will overtake America, the only question is when

Few things would be more powerfully symbolic of the shift in the balance of global economic power than to have oil traded in the Chinese renminbi rather than the American dollar.

True, no one is going to price a barrel of West Texas Intermediate Crude in renminbi tomorrow. But you can see how that could change. Oil is traded in dollars for economic reasons – not sentimental ones. The oil business pretty much started in the US (vividly portrayed in the film There Will be Blood), the giant oil companies are still mostly American, and the US has long been the world's largest consumer, importer and one of the largest producers of oil. The presidency of George W Bush offered ample evidence of the intimate connections between politics and oil. And the dollar is easily the most traded currency in the world. As such, it makes sense to trade oil in dollars.

Yet the financial tectonic plates are shifting – fast. Yesterday the president of the World Bank, Robert Zoellick, articulated what must be weighing on the minds of many Western policy-makers. A legacy of the current crisis "may be a recognition of changed economic power relations". In other words, the recession has accelerated the rise of China. The brutal truth is that for most of the next decade China's economy will grow by more than 10 per cent a year; America's by less than 2 per cent. China will soon be the world's largest economy, and largest creditor nation, a position enjoyed by a pre-eminent America in the 1950s. China will also be the largest consumer of oil, which will help push trading in it and other commodities towards a "basket" of currencies.

Now America is the world's greatest debtor, she can no longer sustain her role as protector of the world's only reserve currency in the long term. The humbling of Wall Street was proof that the American system was not invincible. Suddenly, a G20 embracing China, India and the other emerging powers is the only forum that matters. China has helped bail out our banks. Spats with the Americans and Europeans are set to grow more bitter. Yesterday the head of the IMF, Dominique Strauss-Kahn and the president of the European Central Bank, Jean-Claude Trichet, resumed their attack on the value of the yuan. Next will come an increasing US resentment at the vast debts built up with China, and, in turn, Chinese nervousness about their long-term worth.

And that is the paradox. China holds approaching $3 trillion in dollar assets, so she cannot afford to see the dollar collapse. Longer term, China does want to become less reliant on the dollar as a place to keep its savings. America needs China to buy her Treasury bills; and China needs America to buy her exports. They are like two drunken giants leaning on each other. Yet a sobering reckoning of some sorts seems inevitable; and it is difficult to see how both can be winners.