@Jamie
Having read through the downloaded book I don't think Mackay claims to have any unique insight or staggeringly original results, and he does say repeatedly that many of his numbers are estimates and likely to be in error -- and I don't think he shows any strong personal bias, except the one that much of what is said in this area is completely innumerate rubbish (save the planet by unplugging your mobile phone charger etc), which is difficlut to disagree with.
What it does do better than anything else I've seen is to put the whole thing in perspective and give a real insight into how difficult it will be to wean the world off its fossil-fuel tit, and how most of the supposed solutions put forward by governments -- and environmentalists -- don't even come *close* to solving the problem, at least not without implementation on a truly heroic scale.
And it's written in an accessible style which should make it understandable by not just the man in the street, but also journalists and even quite possibly politicians :-)