Hands up those who think that an enforceable, workable international agreement to limit emissions is still possible? If your hand is up you must be a diehard climate activist. Although the hopes for such an agreement have been in terminal decline for years, two events of the past few days would, in any reasonable debate, cause life support for those hopes to be switched off.

The first is the decision by several key leaders, notably Chinese President Xi Jinping , Indian Prime Minister Narendra Modi , German Chancellor Angela Merkel and our own Prime Minister Tony Abbott to skip a meeting of world leaders on climate change in New York on September 23.