The meeting of the heads of government of the Group of 20 leading high-income and emerging countries in London is a defining moment. At a time of economic crisis, the leaders of countries that generate the vast bulk of global economic activity must point the way towards shared solutions. If they do achieve this, the summit may not be regarded as the beginning of the end of this crisis, but it will surely be the end of the beginning.

The very fact that the G20 is seen as the right body to address this challenge is significant. No longer is it possible for a small number of western countries – together with Japan – to resolve the world's economic challenges. While the G20 is too large a grouping, it contains all the world's important economies. Here, above all, the rising powers do not feel they are mere guests, as at meetings of the Group of Eight leading high-income countries. This, then, is indeed the right group. Its first summit was in Washington last November. The London summit should be the second in a series.

Furthermore, substantial progress has been made, helped by useful background papers from the International Monetary Fund. Never has the wisdom of the founders of the Bretton Woods institutions and the World Trade Organisation been more evident than in this crisis. Unlike in the 1930s, the existence of these institutions has reinforced habits of co-operation and safeguarded principles of openness. They remind us, by their existence and precepts, that global crises do indeed need global solutions.