The UK government could be forgiven for heading into the Copenhagen talks with a slightly holier-than-thou attitude. The Climate Change Act sets strict targets for greenhouse gas emission reductions by 2050 - reductions of 80%. Other countries have done far less to set the framework for the future.
Easy to say isn't it? Do we really understand what 80% means? It means only emitting one fifth the polluting greenhouse gases that we do now. How will we do that?
We could: drive one fifth of the way to work, have the TV on for one fifth the hours, heat our houses for one fifth the time, use our computers for one fifth the time, heat our water for one fifth the time, have one fifth the number of cups of tea, travel one fifth the distance for our holidays, give one fifth the number of Christmas presents and cut everything else by four fifths too. But we won't will we?
It seems clear that business as usual, but tightening our belts by 80%, isn't the solution. Instead we are going to change the way that we generate energy so that we can continue to use lots but its production results in far less pollution - nuclear power, windfarms, tidal barrages, solar panels are all potentially part of the answer. So will be better car technology - and better public transport to replace car journeys. And cutting down on energy waste is a sensible place to start - although it won't get us very far towards the 80% needed. So there is quite a lot of belt-tightening involved too.
It's just simple maths.
One of my memories from the party conference season was from Manchester when a gentleman came up to me after a fringe event and thanked me for what the panel had said. He said that his son was doing a Master's degree on something environmental and that he himself had always thought that this climate change stuff was a bit of a left wing plot and a load of hysteria. He said that the words of the panel had persuaded him that this was a very serious problem and now he was going to phone his son to say how glad he was that he was working in this area. It was a lovely moment.