[Niall Ferguson is the author of 'The Ascent of Money: A Financial History of the World' published in paperback by Penguin this week]

Two years ago, economist Moritz Schularick and I coined the word"Chimerica" to describe what we saw as the key relationship in the then-booming global economy: China plus America. Cheap Chinese labour was making US corporations highly profitable. Spendthrift American consumers, in turn, were keeping Chinese corporations busy with export orders. And the Chinese monetary authorities were converting export surpluses into dollar denominated reserves with the aim of preventing their own currency from appreciating. The unintended consequence was a multi-billion dollar credit line to the United States, financing America's deficit at rock-bottom rates.

It was those low long-term rates – combined with monetary policy errors by the Fed, excessive bank leverage and reckless financial engineering – that inflated the American property bubble, the bursting of which triggered this crisis.

To simplify the story, think of an unhappy marriage in which one partner does all the saving, while the other does all the spending. (We all know at least one couple like that.) But then the partner with the retail therapy habit maxes out on his/her credit cards. At the same time, the parsimonious partner finds her/his job under threat. What previously was a stable relationship is suddenly on the rocks.

In February, the People's Daily acknowledged the"global importance and influence" of Chimerica, but warned of an impending"period of chillness". Could this be one of those great turning points in history, when the balance of power tilts decisively away from an established power and towards a rising challenger? It is possible. Financial crises often accelerate the gradual shifting of the geopolitical tectonic plates; they are to history what earthquakes are to geology.

It was inflation that undermined the foundations of Habsburg power and opened the way for the Dutch Republic. It was the disastrous Mississippi Bubble of 1718-19 that fatally weakened ancien régime France, while Britain survived the contemporaneous South Sea Bubble with its fiscal system intact. For most of the nineteenth century, financial crises in the United States had only marginal effects on the City of London. By 1907, however, a Wall Street crash could send a shockwave across the entire British Empire, a harbinger of a new era of American power.

Something similar may be happening as a consequence of the American financial crisis that began nearly two years ago....