Vinod Thomas, the IEG's director-general, sums up the dilemma: "Climate change threatens to derail development, while business-as-usual development threatens to destabilise the climate."

Managing this tension will involve a lot more reflection about the trade-off between growth, the mitigation of climate change and adaptation to its effects. At the bank, some thinking does seem to be going on: that is the topic of its next World Development Report - an annual assessment of the fight against poverty.

Whatever the report says, it will be hard to convince poor countries that action over climate change is a necessity, not a luxury, and that it will not impede growth. The Bertin shambles may go down as a warning for everybody involved in a giant exercise in on-the-job learning.

© The Economist Newspaper Limited 2009