Just what has been achieved here? The summit’s warm words on climate change were criticised by the UN secretary-general himself yesterday, who said they did not go far enough. China and India now “recognise the scientific view” that temperatures should not go more than 2 degrees centigrade above pre-industrial levels, but whether they are prepared to sacrifice one jot of economic growth to achieve that is still open to debate.

The 17 biggest emitters will work to “identify a global goal” for emissions cuts, but the one the G8 proposed – 50 per cent, was rejected.

And even though the prime minister points out that the G8 signed up to what he calls a “historic” target of 80 per cent cuts itself, what they are talking about are goals and aspirations, not binding commitments. The prospect of a new global framework for tackling climate change being agreed  in Copenhagen in about five months from now seems daunting indeed, though we have a UN Climate Change summit in New York and the G20 in Pittsburgh before we get to Denmark itself.

Various bricks need to fall into place. Barack Obama needs to drag climate legislation through the US Senate, despite objections from his own Democrats representing coal states; a vast green technology fund will have to be created, despite the global recession, to persuade China, India, Brazil, Mexico and the rest that they will have not have to foot the entire bill for a greener future themselves.      

And the rich nations may have to reach some compromise on interim cuts, cuts by 2020 rather than 2050, to get China and India to budge. So climate change negotiators certainly have their work cut out, and for all the talk here in Italy this week, I still can’t help feeling we are still fiddling while Rome burns.