Mark Walport's lecture at the Cambridge Centre for Science and Policy is now available on YouTube. It's simultaneously fascinating and infuriating and I encourage readers to watch, although it's an hour long and there's half an hour of questions afterwards, so you will need a clear diary.
Walport is new to his post and to the climate debate and so we should probably cut him some slack, but it has to be said that the scientific part of the lecture was very shallow stuff - much more in the rally-the-troops mould than a serious look at the science of global warming. So we got lots of stuff about carbon emissions and atmospheric lifetimes but nothing - and I mean nothing - about climate sensitivity. This could be seen as an astonishing oversight, but it makes sense if you see his lecture as trying to shore up support for the global warming hypothesis rather than informing the audience.