I've only read your book at speed, I will reread it more carefully but I thought you may wish a critique so you took the trouble to write it. In general I find your book skips lightly around from subject to subject, but you cover so much ground that that is normal for a general science book. I think it covers enough ground though, and what you do explain is explained clearly enough, that it should be on the curriculum, with only a few changes. My criticisms aren't major and are intended to give you some perspective if you ever release a second edition, so well done for writing it and giving it away for free.

I think it would be funny for you to include a sleeve note that compares the carbon footprint of reading it online and the carbon footprint of printing it out. (I was trying to work that out in my head - how long will I take to read it? How many other people would read it if I printed it?) and I have no idea.

On page 65, you describe albedo in terms of the colour of a T shirt in the sun affecting it's temperature. I think this a poor analogy and a bit distracting, as white cotton tends to be more transparent than dyed black cotton, and people happily wear both in equatorial areas. Perhaps you could find a better analogy, like car-seats or footballs. You mention on page 80 that 'The same albedo effect happens when coniferous trees move into previously scrubby, snowy areas, like the Tundra'. I think that is an important point that you should expand on as there are reforestation schemes above the winter snowline in the UK and Northern Europe that would be better being closer to the equator. It would be good to read a proper analysis of whether albedo altering schemes like painting existing rooftops white would have a benefit that outweighs the cost of the required paint or if such an idea is insignificant. And with as many facts and figures as you can be bothered investigating!

Chapter Nine on page 102 talks of over population, and you start by justifying having two children. You don't do it very well though, and maybe you shouldn't raise the issue since it doesn't affect the validity of your arguments. You said "By only having two children we are, in effect, contributing to the reduction in global population, because the “Replacement Fertility” in our part of the world is around 2.1 children per couple."
That is a logical fallacy, or at least you being disingenuous in terms of environmental cost. Two adults who have two kids are not contributing to the reduction of the global population. You are increasing it by two while you are all alive, and hopefully your lives will overlap for a long time. You can't have 0.1 of a child, so just because the TFR is 2.1 in the UK, doesn't mean 'just' having two kids lowers the population. I don't have kids but I am still not really'contributing to the reduction of the global population', only my death will do that or when I start killing humans. It is also implying that your two kids lives will have an equal carbon cost to your own lives, which is optimistic given rates are rising. A statistician, Paul Murtaugh, has estimated with constant emissions each US child would eventually result in six times the lifetime carbon footprint of their parent, though I confess I don't understand why.
You 'blame' / explain your decision to having kids on being human and so suceptible to the needs of your DNA. This is dubious reasoning too. We are all human and some of us don't breed. It wasn't a genetic choice for me not to contribute to the gene pool, it was a rational decision like choosing not to eat meat. My genes can go jump if they don't like it, they are not the boss of me. I could equally say I am genetically predisposed to laziness or self indulgence so I have to fly and drive everywhere.
Anyway, I doubt anyone would criticise you for having two kids and it seems to muddy the book that you bring it up.

You touch on Game Theory on page 114. It is an interesting and relevant subject that you should invest a few more pages in. Similarly, you touch on bio-char on page 228, but dismiss it as insignificant without a supporting argument, which seems an oversight on your part. Do the maths, and then show it.

Page 229 you discuss sabotage, something you have obviously considered. I've found myself in similar positions and I find your advice about this to be too vague to be useful while not specific enough to be dangerous. I think it is essential to point out to potential sabateurs that the last thing they want to do is 'connect' with known activists if they can possibly avoid it.

Hi Danny

Only just noticed your critique, thanks for the effort - if you want to get some dialogue going then please contact me via the web site. This is just a quick response as I understand that overall you don't have many issues; in fact it's good to see so few in such a large book.

First, please bear in mind that it is a little rough and ready in places: I wanted to make this a slightly harder-edged book than the published version so people have a choice (this is particularly notable with the section on sabotage).

No idea about comparative carbon footprints, but if you buy the book anywhere but the UK at present then more carbon is probably generated than reading online; although national energy generation varies tremendously for online reading too.

I understand that skipping among so many areas can be frustrating, but that is countered by quite a few people telling me they were glad I didn't spend too long on each scientific area - I can't win 'em all.

With the child issue, I probably could have added "but it would obviously be better not to have children at all", however I do spend a few pages on population later in the section called "Reproducing" which you should find deals with this. My point in the earlier chapter was to emphasise the power of genetics: yes, you can fight your genetic urges, but they are still very powerful, and play a huge part in overall human behaviour, in the absence of "Tools of Disconnection" (this, again links up in Chapter 13).

Biochar: not enough research yet done, and it's still very much being contested - I don't dismiss it, I merely say it's a possibility.

Sabotage: send me an email for more information. Needless to say, I have made a change to the web site, and you will find links to later articles I have written on this subject in the Resources > Appendices page ( http://www.farnish.plus.com/amatterofscale/links.htm). There are many good reasons for being vague, not all of them legal.

Cheers

Keith