For a conference that is supposedly addressing “sustainability,” it is worth lamenting the absence of a heroic effort to agree on a successor treaty to the Kyoto Accord. If the cataclysmic scenarios implied by neglect of climate change are valid – and extreme estimates, it must be said, could backfire politically by looking implausible or, worse, by producing a “Nero effect” (if Rome is burning, let’s party) – Rio+20’s lack of action should be regarded as an historic failure.