Crises overturn established orders. The financial and economic crises of 2007-09 are no exception. The rise of the G20 to prominence is a watershed in history: for the first time since the industrial revolution, economic power is no longer concentrated in western hands.

The meeting of the G20 at head of government level in Pittsburgh today and tomorrow will be the third such meeting within a year. The first, at the initiative of then US president George W. Bush, took place in Washington, in November 2008. The second, under the chairmanship of the UK’s Gordon Brown, took place in London in April 2009. The Pittsburgh summit, coming so close after the London one, shows that the G20 has become the principal body driving the global response to the crisis.