BBC: A legally-binding international treaty may not be the best way to tackle climate change.
Leading economist Lord Nicholas Stern said that a commitment to sustainable development was more important than a binding deal that "lacked credibility".
He was speaking in Lima, Peru, where negotiators from 194 countries are heading into a second week of UN talks.
They hope to agree a text that would form the basis of new global compact, to be signed in Paris next year.
Many developing countries...